Pub Date : 2002-05-31DOI: 10.1161/01.RES.0000018941.10726.FA
L. Pinderski, M. Fischbein, G. Subbanagounder, M. Fishbein, N. Kubo, H. Cheroutre, L. Curtiss, J. Berliner, W. Boisvert
Previous studies demonstrated that interleukin-10 (IL-10) overexpression decreases formation of early fatty-streak lesions in mice independent of lipoprotein levels. The present studies, using bone marrow transplantation, demonstrate that overexpression of IL-10 by T cells inhibits advanced atherosclerotic lesions in LDL receptor–null mice fed an atherogenic diet. In mice receiving bone marrow from the IL-10 transgenic mice compared with those receiving wild-type marrow, there was a 47% decrease in lesion size and a marked decrease in lesion complexity with an 80% reduction in the necrotic core. Accumulation of cholesterol and phospholipid oxidation products in the aorta was decreased by 50% to 80%, unrelated to plasma lipid or IL-10 levels. Our studies also provide insight into the mechanism of the IL-10–mediated decrease in lesion size. Although a strong influence toward a Th1 phenotype has previously been demonstrated in atherosclerotic models, T lymphocytes in the IL-10 transgenic (Tg) group revealed a marked shift to a Th2 phenotype, with decreased IFN-&ggr; production and an increase in IL-10. Evaluation of specific immunoglobulin subclasses demonstrated a preponderance of IgG1 isotype, characteristic of a Th2 influence on B cell immunoglobulin class-switching in the IL-10 Tg group. A major finding of these studies was altered monocyte/macrophage function in the IL-10 Tg group. Monocytes showed a decrease in activation resulting in decreased expression of IFN-&ggr;. Furthermore, macrophage foam cells within lesions of the IL-10 Tg group exhibited markedly decreased apoptosis. These studies demonstrate that T lymphocyte IL-10 can influence the function of other immune cells to reduce the development of advanced atherosclerotic lesions in mice.
{"title":"Overexpression of Interleukin-10 by Activated T Lymphocytes Inhibits Atherosclerosis in LDL Receptor–Deficient Mice by Altering Lymphocyte and Macrophage Phenotypes","authors":"L. Pinderski, M. Fischbein, G. Subbanagounder, M. Fishbein, N. Kubo, H. Cheroutre, L. Curtiss, J. Berliner, W. Boisvert","doi":"10.1161/01.RES.0000018941.10726.FA","DOIUrl":"https://doi.org/10.1161/01.RES.0000018941.10726.FA","url":null,"abstract":"Previous studies demonstrated that interleukin-10 (IL-10) overexpression decreases formation of early fatty-streak lesions in mice independent of lipoprotein levels. The present studies, using bone marrow transplantation, demonstrate that overexpression of IL-10 by T cells inhibits advanced atherosclerotic lesions in LDL receptor–null mice fed an atherogenic diet. In mice receiving bone marrow from the IL-10 transgenic mice compared with those receiving wild-type marrow, there was a 47% decrease in lesion size and a marked decrease in lesion complexity with an 80% reduction in the necrotic core. Accumulation of cholesterol and phospholipid oxidation products in the aorta was decreased by 50% to 80%, unrelated to plasma lipid or IL-10 levels. Our studies also provide insight into the mechanism of the IL-10–mediated decrease in lesion size. Although a strong influence toward a Th1 phenotype has previously been demonstrated in atherosclerotic models, T lymphocytes in the IL-10 transgenic (Tg) group revealed a marked shift to a Th2 phenotype, with decreased IFN-&ggr; production and an increase in IL-10. Evaluation of specific immunoglobulin subclasses demonstrated a preponderance of IgG1 isotype, characteristic of a Th2 influence on B cell immunoglobulin class-switching in the IL-10 Tg group. A major finding of these studies was altered monocyte/macrophage function in the IL-10 Tg group. Monocytes showed a decrease in activation resulting in decreased expression of IFN-&ggr;. Furthermore, macrophage foam cells within lesions of the IL-10 Tg group exhibited markedly decreased apoptosis. These studies demonstrate that T lymphocyte IL-10 can influence the function of other immune cells to reduce the development of advanced atherosclerotic lesions in mice.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"102 1","pages":"1064-1071"},"PeriodicalIF":0.0,"publicationDate":"2002-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79591715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-31DOI: 10.1161/01.RES.0000019242.51541.99
J. Peters, R. Farrenkopf, S. Clausmeyer, J. Zimmer, S. Kantachuvesiri, M. Sharp, J. Mullins
Intracardiac renin is considered to be involved in the pathogenesis of cardiac hypertrophy, fibrosis, and myocardial infarction. Cardiac renin is predominantly derived from the circulation, because preprorenin is not expressed locally and uptake of renin has been demonstrated. One mechanism of internalization recently described involves the mannose-6-phosphate receptor and requires glycosylation of renin. Based on previous observations, we considered the existence of another pathway of uptake, not requiring glycosylation and predominantly involving prorenin. This hypothesis and its functional consequences were investigated in vitro and in vivo. We demonstrate that isolated adult cardiomyocytes internalize unglycosylated prorenin, which is followed by the generation of angiotensins. We further show that transgenic rats, expressing the ren-2d renin gene in an inducible manner, exhibit markedly enhanced levels of unglycosylated renin within intracellular compartments in the heart as a consequence of the induction of hepatic transgene expression and the rise of circulating unglycosylated prorenin levels. Because in this model severe cardiac damage occurs as a consequence of the rise of circulating prorenin levels, internalization of prorenin into cardiac cells is likely to play a key role in this process.
{"title":"Functional Significance of Prorenin Internalization in the Rat Heart","authors":"J. Peters, R. Farrenkopf, S. Clausmeyer, J. Zimmer, S. Kantachuvesiri, M. Sharp, J. Mullins","doi":"10.1161/01.RES.0000019242.51541.99","DOIUrl":"https://doi.org/10.1161/01.RES.0000019242.51541.99","url":null,"abstract":"Intracardiac renin is considered to be involved in the pathogenesis of cardiac hypertrophy, fibrosis, and myocardial infarction. Cardiac renin is predominantly derived from the circulation, because preprorenin is not expressed locally and uptake of renin has been demonstrated. One mechanism of internalization recently described involves the mannose-6-phosphate receptor and requires glycosylation of renin. Based on previous observations, we considered the existence of another pathway of uptake, not requiring glycosylation and predominantly involving prorenin. This hypothesis and its functional consequences were investigated in vitro and in vivo. We demonstrate that isolated adult cardiomyocytes internalize unglycosylated prorenin, which is followed by the generation of angiotensins. We further show that transgenic rats, expressing the ren-2d renin gene in an inducible manner, exhibit markedly enhanced levels of unglycosylated renin within intracellular compartments in the heart as a consequence of the induction of hepatic transgene expression and the rise of circulating unglycosylated prorenin levels. Because in this model severe cardiac damage occurs as a consequence of the rise of circulating prorenin levels, internalization of prorenin into cardiac cells is likely to play a key role in this process.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"5 1","pages":"1135-1141"},"PeriodicalIF":0.0,"publicationDate":"2002-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88326190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-31DOI: 10.1161/01.RES.0000019240.72809.76
B. Rauch, E. Bretschneider, M. Braun, K. Schrör
Pro–matrix metalloproteinase-2 (pro–MMP-2) is expressed in vascular smooth muscle cells (SMCs). We report that activated coagulation factor X (FXa) induces the release of MMP-2 (65 kDa) from human SMCs. In addition, FXa cleaves pro–MMP-2 (72 kDa) into MMP-2. Pro–MMP-2 and MMP-2 were determined by gelatin zymography. MMP-2 was generated in conditioned medium containing pro–MMP-2 in a concentration-dependent fashion by FXa (3 to 100 nmol/L). FX at concentrations up to 300 nmol/L was ineffective. The conversion of pro–MMP-2 to MMP-2 was inhibited by a selective FXa inhibitor (DX-9065a) at 3 to 10 &mgr;mol/L. There was a concentration-dependent induction of an intermediate MMP-2 form (68 kDa) in lysates of FXa-treated cells. This indicates that cellular mechanisms are involved in FXa-induced conversion of pro–MMP-2. As a possible biological consequence of MMP-2 activation by FXa, DNA synthesis and matrix invasion of SMCs were determined. Both were stimulated by FXa and inhibited by the selective FXa inhibitor DX-9065a and the MMP inhibitor GM 6001 but not by hirudin or aprotinin. It is concluded that stimulation of SMCs by FXa increases the levels of MMP-2 in the extracellular space and that two different mechanisms are involved: release of active MMP-2 and cleavage of secreted pro–MMP-2. Both might contribute to the mitogenic potency of FXa and FXa-stimulated matrix invasion of SMCs.
{"title":"Factor Xa Releases Matrix Metalloproteinase-2 (MMP-2) From Human Vascular Smooth Muscle Cells and Stimulates the Conversion of Pro–MMP-2 to MMP-2: Role of MMP-2 in Factor Xa–Induced DNA Synthesis and Matrix Invasion","authors":"B. Rauch, E. Bretschneider, M. Braun, K. Schrör","doi":"10.1161/01.RES.0000019240.72809.76","DOIUrl":"https://doi.org/10.1161/01.RES.0000019240.72809.76","url":null,"abstract":"Pro–matrix metalloproteinase-2 (pro–MMP-2) is expressed in vascular smooth muscle cells (SMCs). We report that activated coagulation factor X (FXa) induces the release of MMP-2 (65 kDa) from human SMCs. In addition, FXa cleaves pro–MMP-2 (72 kDa) into MMP-2. Pro–MMP-2 and MMP-2 were determined by gelatin zymography. MMP-2 was generated in conditioned medium containing pro–MMP-2 in a concentration-dependent fashion by FXa (3 to 100 nmol/L). FX at concentrations up to 300 nmol/L was ineffective. The conversion of pro–MMP-2 to MMP-2 was inhibited by a selective FXa inhibitor (DX-9065a) at 3 to 10 &mgr;mol/L. There was a concentration-dependent induction of an intermediate MMP-2 form (68 kDa) in lysates of FXa-treated cells. This indicates that cellular mechanisms are involved in FXa-induced conversion of pro–MMP-2. As a possible biological consequence of MMP-2 activation by FXa, DNA synthesis and matrix invasion of SMCs were determined. Both were stimulated by FXa and inhibited by the selective FXa inhibitor DX-9065a and the MMP inhibitor GM 6001 but not by hirudin or aprotinin. It is concluded that stimulation of SMCs by FXa increases the levels of MMP-2 in the extracellular space and that two different mechanisms are involved: release of active MMP-2 and cleavage of secreted pro–MMP-2. Both might contribute to the mitogenic potency of FXa and FXa-stimulated matrix invasion of SMCs.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"25 1","pages":"1122-1127"},"PeriodicalIF":0.0,"publicationDate":"2002-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81814109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-31DOI: 10.1161/01.RES.0000021114.92282.FA
G. Pare, A. Krust, R. Karas, S. Dupont, M. Aronovitz, P. Chambon, M. Mendelsohn
Blood vessel cells express the 2 known estrogen receptors, &agr; and &bgr; (ER&agr;, ER&bgr;), which are thought to mediate estrogen inhibition of vascular injury and atherosclerosis, but the relative role of ER&agr; and ER&bgr; in these events is controversial. Estrogen inhibits the vascular injury response to the same extent in ovariectomized female wild-type mice and in the original single gene knockout mice for ER&agr; (ER&agr;KOChapel Hill [ER&agr;KOCH]) and ER&bgr; (ER&bgr;KOChapel Hill [ER&bgr;KOCH]). In double gene knockout mice generated by crossing these animals (ER&agr;,&bgr;KOCH), estrogen no longer inhibits medial thickening after vascular injury, but still inhibits vascular smooth muscle cell proliferation and increases uterine weight. The partial retention of estrogen responsiveness in ER&agr;,&bgr;KOCH mice could be due either to the presence of a novel, unidentified estrogen receptor or to functional expression of an estrogen receptor-&agr; splice variant in the parental ER&agr;KOCH mice. To distinguish between these possibilities, we studied recently generated mice fully null for estrogen receptor &agr; (ER&agr;KOStrasbourg [ER&agr;KOSt]) and examined the effect of estrogen on the response to vascular injury. In the present study, we show that after vascular injury in ovariectomized ER&agr;KOSt mice, estrogen has no detectable effect on any measure of vascular injury, including medial area, proteoglycan deposition, or smooth muscle cell proliferation. These data demonstrate that estrogen receptor-&agr; mediates the protective effects of estrogen on the response to vascular injury.
血管细胞表达2种已知的雌激素受体&agr;bgr;(ER&agr;， ER&bgr;)，它们被认为介导了雌激素对血管损伤和动脉粥样硬化的抑制，但ER&agr的相对作用;和ER&bgr;在这些事件中是有争议的。雌激素对去卵巢雌性野生型小鼠血管损伤反应的抑制程度与ER&agr原单基因敲除小鼠相同;(ER&agr;KOChapel Hill [ER&agr;KOCH])和ER&bgr;(ER&bgr;KOChapel Hill [ER&bgr;KOCH])。在这些动物杂交产生的双基因敲除小鼠(ER&agr;，&bgr;KOCH)中，雌激素不再抑制血管损伤后内侧增厚，但仍抑制血管平滑肌细胞增殖，增加子宫重量。ER&agr，&bgr;KOCH小鼠雌激素反应性的部分保留可能是由于存在一种新的，未知的雌激素受体或雌激素受体-&agr的功能性表达。在亲代ER&agr;KOCH小鼠中的剪接变异体。为了区分这些可能性，我们研究了最近产生的完全没有雌激素受体&agr;(ER&agr;KOStrasbourg [ER&agr;KOSt])研究雌激素对血管损伤反应的影响。在本研究中，我们发现卵巢切除的ER&agr;KOSt小鼠血管损伤后，雌激素对血管损伤的任何测量都没有可检测到的影响，包括内侧面积、蛋白多糖沉积或平滑肌细胞增殖。这些数据表明雌激素受体-&agr;介导雌激素对血管损伤反应的保护作用。
{"title":"Estrogen Receptor-&agr; Mediates the Protective Effects of Estrogen Against Vascular Injury","authors":"G. Pare, A. Krust, R. Karas, S. Dupont, M. Aronovitz, P. Chambon, M. Mendelsohn","doi":"10.1161/01.RES.0000021114.92282.FA","DOIUrl":"https://doi.org/10.1161/01.RES.0000021114.92282.FA","url":null,"abstract":"Blood vessel cells express the 2 known estrogen receptors, &agr; and &bgr; (ER&agr;, ER&bgr;), which are thought to mediate estrogen inhibition of vascular injury and atherosclerosis, but the relative role of ER&agr; and ER&bgr; in these events is controversial. Estrogen inhibits the vascular injury response to the same extent in ovariectomized female wild-type mice and in the original single gene knockout mice for ER&agr; (ER&agr;KOChapel Hill [ER&agr;KOCH]) and ER&bgr; (ER&bgr;KOChapel Hill [ER&bgr;KOCH]). In double gene knockout mice generated by crossing these animals (ER&agr;,&bgr;KOCH), estrogen no longer inhibits medial thickening after vascular injury, but still inhibits vascular smooth muscle cell proliferation and increases uterine weight. The partial retention of estrogen responsiveness in ER&agr;,&bgr;KOCH mice could be due either to the presence of a novel, unidentified estrogen receptor or to functional expression of an estrogen receptor-&agr; splice variant in the parental ER&agr;KOCH mice. To distinguish between these possibilities, we studied recently generated mice fully null for estrogen receptor &agr; (ER&agr;KOStrasbourg [ER&agr;KOSt]) and examined the effect of estrogen on the response to vascular injury. In the present study, we show that after vascular injury in ovariectomized ER&agr;KOSt mice, estrogen has no detectable effect on any measure of vascular injury, including medial area, proteoglycan deposition, or smooth muscle cell proliferation. These data demonstrate that estrogen receptor-&agr; mediates the protective effects of estrogen on the response to vascular injury.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"2 1","pages":"1087-1092"},"PeriodicalIF":0.0,"publicationDate":"2002-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85575214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000018002.43041.08
H. Al‐Kateb, S. Bähring, K. Hoffmann, K. Strauch, A. Busjahn, G. Nürnberg, M. Jouma, Eckehard K F Bautz, H. A. Dresel, F. Luft
We studied a Syrian family with 3 children who had low-density lipoprotein cholesterol (LDL) concentrations of 13.3, 12.2, and 8.6 mmol/L, respectively. Three other siblings and the parents all had LDL values <4.52 mmol/L, suggesting an autosomal-recessive mode of inheritance. The extended pedigree had 66 additional persons with normal LDL values. A genome-wide scan in the core family with 427 markers showed support for linkage on both chromosomes 1 and 13. Markers on chromosome 1 revealed a 3.07 multipoint LOD score between 1p36.1-p35, an 18-cM interval. Surprisingly, we also found linkage to 13q22-q32, a 14-cM interval, with a 3.08 LOD score. We had identified this locus earlier as containing a gene strongly influencing LDL in another Arab family with autosomal-dominant familial hypercholesterolemia and in normal dizygotic twins. We found evidence for an interaction between these loci. We next genotyped our twin panel and confirmed linkage of the 1p36.1-p35 locus to LDL (P <0.002) in this normal population. Elucidation of ARH, the LDL receptor adaptor protein at chromosome 1p35, caused us to sequence that gene. We first identified the genomic structure of ARH gene and then sequenced the gene in our family. We found an intron 1 acceptor splice-site mutation. This mutation was not found in any other family members, in 31 nonrelated Syrian persons, or in 30 Germans. Our results underscore the importance of ARH on chromosome 1 and the chromosome 13q locus to LDL, not only in families with unusual illnesses, but also to the general population.
我们研究了一个有3个孩子的叙利亚家庭，他们的低密度脂蛋白胆固醇(LDL)浓度分别为13.3、12.2和8.6 mmol/L。其他3名兄弟姐妹和父母的LDL值均<4.52 mmol/L，提示常染色体隐性遗传模式。扩展谱系中有66人LDL值正常。对核心家族的427个标记进行全基因组扫描显示，1号和13号染色体上都存在连锁。1号染色体上的标记显示，1p36.1-p35之间的多点LOD评分为3.07，间隔为18cm。令人惊讶的是，我们还发现了与13q22-q32的连锁，间隔为14 cm, LOD评分为3.08。我们早前发现，在另一个常染色体显性家族性高胆固醇血症的阿拉伯家族和正常的异卵双胞胎中，这个位点含有一个强烈影响LDL的基因。我们发现了这些基因座之间相互作用的证据。接下来，我们对双胞胎进行基因分型，并确认在正常人群中存在1p36.1-p35位点与LDL的连锁关系(P <0.002)。染色体1p35上的低密度脂蛋白受体衔接蛋白ARH的解析使我们对该基因进行了测序。我们首先确定了ARH基因的基因组结构，然后对我们家族的ARH基因进行了测序。我们发现一个内含子1受体剪接位点突变。在其他家族成员、31名无血缘关系的叙利亚人和30名德国人中均未发现该突变。我们的研究结果强调了ARH在1号染色体和13q染色体上对LDL位点的重要性，不仅在患有罕见疾病的家庭中，而且对一般人群也是如此。
{"title":"Mutation in the ARH Gene and a Chromosome 13q Locus Influence Cholesterol Levels in a New Form of Digenic-Recessive Familial Hypercholesterolemia","authors":"H. Al‐Kateb, S. Bähring, K. Hoffmann, K. Strauch, A. Busjahn, G. Nürnberg, M. Jouma, Eckehard K F Bautz, H. A. Dresel, F. Luft","doi":"10.1161/01.RES.0000018002.43041.08","DOIUrl":"https://doi.org/10.1161/01.RES.0000018002.43041.08","url":null,"abstract":"We studied a Syrian family with 3 children who had low-density lipoprotein cholesterol (LDL) concentrations of 13.3, 12.2, and 8.6 mmol/L, respectively. Three other siblings and the parents all had LDL values <4.52 mmol/L, suggesting an autosomal-recessive mode of inheritance. The extended pedigree had 66 additional persons with normal LDL values. A genome-wide scan in the core family with 427 markers showed support for linkage on both chromosomes 1 and 13. Markers on chromosome 1 revealed a 3.07 multipoint LOD score between 1p36.1-p35, an 18-cM interval. Surprisingly, we also found linkage to 13q22-q32, a 14-cM interval, with a 3.08 LOD score. We had identified this locus earlier as containing a gene strongly influencing LDL in another Arab family with autosomal-dominant familial hypercholesterolemia and in normal dizygotic twins. We found evidence for an interaction between these loci. We next genotyped our twin panel and confirmed linkage of the 1p36.1-p35 locus to LDL (P <0.002) in this normal population. Elucidation of ARH, the LDL receptor adaptor protein at chromosome 1p35, caused us to sequence that gene. We first identified the genomic structure of ARH gene and then sequenced the gene in our family. We found an intron 1 acceptor splice-site mutation. This mutation was not found in any other family members, in 31 nonrelated Syrian persons, or in 30 Germans. Our results underscore the importance of ARH on chromosome 1 and the chromosome 13q locus to LDL, not only in families with unusual illnesses, but also to the general population.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"44 1","pages":"951-958"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75843358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000019783.88094.BA
James F. Kneller, Renqiang Zou, E. Vigmond, Zhiguo Wang, L. J. Leon, S. Nattel
Classical concepts of atrial fibrillation (AF) have been rooted in Moe’s multiple-wavelet hypothesis and simple cellular-automaton computer model. Recent experimental work has raised questions about the multiple-wavelet mechanism, suggesting a discrete “driver region” underlying AF. We reexplored the theoretical basis for AF with a 2-dimensional computer model of a 5×10-cm sheet of atrial cells with realistic ionic and coupling properties. Vagal actions were formulated based on patch-clamp studies of acetylcholine (ACh) effects. In control, a single extrastimulus resulted in a highly meandering unstable spiral wave. Simulated electrograms showed fibrillatory activity, with a dominant frequency (DF, 6.5 Hz) that correlated with the mean rate. Uniform ACh reduced core meander of the spiral wave by ≈70% (as measured by the standard deviation of spiral-wave tip position) and accelerated the DF to 17.0 Hz. Simulated vagally induced refractoriness heterogeneity caused wavefront breakup as accelerated reentrant activity in regions of short refractoriness impinged on regions unable to respond in a 1:1 fashion because of longer refractoriness. In 7 simulations spanning the range of conditions giving sustained AF, 5 were maintained by single dominant spiral waves. On average, 3.0±1.3 wavelets were present (range, 1 to 7). Most wavelets were short-lived and did not contribute to AF maintenance. In contrast to predictions of the multiple-wavelet hypothesis, but in agreement with recent experimental evidence, our model indicates that AF can result from relatively stable primary spiral-wave generators and is significantly organized. Our results suggest that vagal AF may arise from ACh-induced stabilization of the primary spiral-wave generator and disorganization of the heterogeneous tissue response. The full text of this article is available at http://www.circresaha.org.
{"title":"Cholinergic Atrial Fibrillation in a Computer Model of a Two-Dimensional Sheet of Canine Atrial Cells With Realistic Ionic Properties","authors":"James F. Kneller, Renqiang Zou, E. Vigmond, Zhiguo Wang, L. J. Leon, S. Nattel","doi":"10.1161/01.RES.0000019783.88094.BA","DOIUrl":"https://doi.org/10.1161/01.RES.0000019783.88094.BA","url":null,"abstract":"Classical concepts of atrial fibrillation (AF) have been rooted in Moe’s multiple-wavelet hypothesis and simple cellular-automaton computer model. Recent experimental work has raised questions about the multiple-wavelet mechanism, suggesting a discrete “driver region” underlying AF. We reexplored the theoretical basis for AF with a 2-dimensional computer model of a 5×10-cm sheet of atrial cells with realistic ionic and coupling properties. Vagal actions were formulated based on patch-clamp studies of acetylcholine (ACh) effects. In control, a single extrastimulus resulted in a highly meandering unstable spiral wave. Simulated electrograms showed fibrillatory activity, with a dominant frequency (DF, 6.5 Hz) that correlated with the mean rate. Uniform ACh reduced core meander of the spiral wave by ≈70% (as measured by the standard deviation of spiral-wave tip position) and accelerated the DF to 17.0 Hz. Simulated vagally induced refractoriness heterogeneity caused wavefront breakup as accelerated reentrant activity in regions of short refractoriness impinged on regions unable to respond in a 1:1 fashion because of longer refractoriness. In 7 simulations spanning the range of conditions giving sustained AF, 5 were maintained by single dominant spiral waves. On average, 3.0±1.3 wavelets were present (range, 1 to 7). Most wavelets were short-lived and did not contribute to AF maintenance. In contrast to predictions of the multiple-wavelet hypothesis, but in agreement with recent experimental evidence, our model indicates that AF can result from relatively stable primary spiral-wave generators and is significantly organized. Our results suggest that vagal AF may arise from ACh-induced stabilization of the primary spiral-wave generator and disorganization of the heterogeneous tissue response. The full text of this article is available at http://www.circresaha.org.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"29 1","pages":"e73-e87"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82725683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000018627.89528.6F
G. Schram, M. Pourrier, P. Melnyk, S. Nattel
The cardiac electrical system is designed to ensure the appropriate rate and timing of contraction in all regions of the heart, which are essential for effective cardiac function. Well-controlled cardiac electrical activity depends on specialized properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Cardiac electrical specialization was first recognized in the mid 1800s, but over the past 15 years, an enormous amount has been learned about how specialization is achieved by differential expression of cardiac ion channels. More recently, many aspects of the molecular basis have been revealed. Although the field is potentially vast, an appreciation of key elements is essential for any clinician or researcher wishing to understand modern cardiac electrophysiology. This article reviews the major regionally determined features of cardiac electrical function, discusses underlying ionic bases, and summarizes present knowledge of ion channel subunit distribution in relation to functional specialization.
{"title":"Differential Distribution of Cardiac Ion Channel Expression as a Basis for Regional Specialization in Electrical Function","authors":"G. Schram, M. Pourrier, P. Melnyk, S. Nattel","doi":"10.1161/01.RES.0000018627.89528.6F","DOIUrl":"https://doi.org/10.1161/01.RES.0000018627.89528.6F","url":null,"abstract":"The cardiac electrical system is designed to ensure the appropriate rate and timing of contraction in all regions of the heart, which are essential for effective cardiac function. Well-controlled cardiac electrical activity depends on specialized properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Cardiac electrical specialization was first recognized in the mid 1800s, but over the past 15 years, an enormous amount has been learned about how specialization is achieved by differential expression of cardiac ion channels. More recently, many aspects of the molecular basis have been revealed. Although the field is potentially vast, an appreciation of key elements is essential for any clinician or researcher wishing to understand modern cardiac electrophysiology. This article reviews the major regionally determined features of cardiac electrical function, discusses underlying ionic bases, and summarizes present knowledge of ion channel subunit distribution in relation to functional specialization.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"23 1","pages":"939-950"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88273971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000019540.41697.60
Ichiro Masaki, Y. Yonemitsu, A. Yamashita, Shihoko Sata, Mitsugu Tanii, K. Komori, K. Nakagawa, X. Hou, Y. Nagai, M. Hasegawa, K. Sugimachi, K. Sueishi
Recent studies suggest the possible therapeutic effect of intramuscular vascular endothelial growth factor (VEGF) gene transfer in individuals with critical limb ischemia. Little information, however, is available regarding (1) the required expression level of VEGF for therapeutic effect, (2) the related expression of endogenous angiogenic factors, including fibroblast growth factor-2 (FGF-2), and (3) the related adverse effects due to overexpression of VEGF. To address these issues, we tested effects of overexpression of VEGF165 using recombinant Sendai virus (SeV), as directly compared with FGF-2 gene transfer. Intramuscular injection of SeV strongly boosted FGF-2, resulting in significant therapeutic effects for limb salvage with increased blood perfusion associated with enhanced endogenous VEGF expression in murine models of critical limb ischemia. In contrast, VEGF165 overexpression, 5-times higher than that of baseline on day 1, also strongly evoked endogenous VEGF in muscles, resulting in an accelerated limb amputation without recovery of blood perfusion. Interestingly, viable skeletal muscles of either VEGF165- or FGF-2–treated ischemic limbs showed similar platelet-endothelial cell adhesion molecule-1–positive vessel densities. Maturation of newly formed vessels suggested by smooth muscle cell actin–positive cell lining, however, was significantly disturbed in muscles with VEGF. Further, therapeutic effects of FGF-2 were completely diminished by anti-VEGF neutralizing antibody in vivo, thus indicating that endogenous VEGF does contribute to the effect of FGF-2. These results suggest that VEGF is necessary, but should be delicately regulated to lower expression to treat ischemic limb. The therapeutic effect of FGF-2, associated with the harmonized angiogenic effects seen with endogenous VEGF, provides important insights into therapeutic angiogenesis.
{"title":"Angiogenic Gene Therapy for Experimental Critical Limb Ischemia: Acceleration of Limb Loss by Overexpression of Vascular Endothelial Growth Factor 165 but not of Fibroblast Growth Factor-2","authors":"Ichiro Masaki, Y. Yonemitsu, A. Yamashita, Shihoko Sata, Mitsugu Tanii, K. Komori, K. Nakagawa, X. Hou, Y. Nagai, M. Hasegawa, K. Sugimachi, K. Sueishi","doi":"10.1161/01.RES.0000019540.41697.60","DOIUrl":"https://doi.org/10.1161/01.RES.0000019540.41697.60","url":null,"abstract":"Recent studies suggest the possible therapeutic effect of intramuscular vascular endothelial growth factor (VEGF) gene transfer in individuals with critical limb ischemia. Little information, however, is available regarding (1) the required expression level of VEGF for therapeutic effect, (2) the related expression of endogenous angiogenic factors, including fibroblast growth factor-2 (FGF-2), and (3) the related adverse effects due to overexpression of VEGF. To address these issues, we tested effects of overexpression of VEGF165 using recombinant Sendai virus (SeV), as directly compared with FGF-2 gene transfer. Intramuscular injection of SeV strongly boosted FGF-2, resulting in significant therapeutic effects for limb salvage with increased blood perfusion associated with enhanced endogenous VEGF expression in murine models of critical limb ischemia. In contrast, VEGF165 overexpression, 5-times higher than that of baseline on day 1, also strongly evoked endogenous VEGF in muscles, resulting in an accelerated limb amputation without recovery of blood perfusion. Interestingly, viable skeletal muscles of either VEGF165- or FGF-2–treated ischemic limbs showed similar platelet-endothelial cell adhesion molecule-1–positive vessel densities. Maturation of newly formed vessels suggested by smooth muscle cell actin–positive cell lining, however, was significantly disturbed in muscles with VEGF. Further, therapeutic effects of FGF-2 were completely diminished by anti-VEGF neutralizing antibody in vivo, thus indicating that endogenous VEGF does contribute to the effect of FGF-2. These results suggest that VEGF is necessary, but should be delicately regulated to lower expression to treat ischemic limb. The therapeutic effect of FGF-2, associated with the harmonized angiogenic effects seen with endogenous VEGF, provides important insights into therapeutic angiogenesis.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"17 1","pages":"966-973"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74773352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000018625.25212.1E
O. Zeitz, A. Maass, Phuc Van Nguyen, Geerd Hensmann, H. Kögler, K. Möller, G. Hasenfuss, P. Janssen
Hydroxyl radicals (OH) are involved in the development of reperfusion injury and myocardial failure. In the acute phase of the OH-mediated diastolic dysfunction, increased intracellular Ca2+ levels and alterations of myofilaments may play a role, but the relative contribution of these systems to myocardial dysfunction is unknown. Intact contracting cardiac trabeculae from rabbits were exposed to OH, resulting in an increase in diastolic force (Fdia) by 540%. Skinned fiber experiments revealed that OH-exposed preparations were sensitized for Ca2+ (EC50: 3.27±0.24×10−6 versus 2.69±0.15×10−6 mol/L;P <0.05), whereas maximal force development was unaltered. Western blots showed a proteolytic degradation of troponin T (TnT) with intact troponin I (TnI). Blocking of calpain I by MDL-28.170 inhibited both TnT-proteolysis and Ca2+ sensitization, but failed to prevent the acute diastolic dysfunction in the intact preparation. The OH-induced diastolic dysfunction was similar in preparations with intact (540±93%) and pharmacologically blocked sarcoplasmic reticulum (539±77%), and was also similar in presence of the L-type Ca2+-channel antagonist verapamil. In sharp contrast, inhibition of the reverse-mode sodium-calcium exchange by KB-R7943 preserved diastolic function completely. Additional experiments were performed in rat myocardium; the rise in diastolic force was comparable to rabbit myocardium, but Ca2+ sensitivity was unchanged and maximal force development was reduced. This was associated with a degradation of TnI, but not TnT. Electron microscopic analysis revealed that OH did not cause irreversible membrane damage. We conclude that OH-induced acute diastolic dysfunction is caused by Ca2+ influx via reverse mode of the sodium-calcium exchanger. Degradation of troponins appears to be species-dependent but does not contribute to the acute diastolic dysfunction.
羟基自由基(OH)参与再灌注损伤和心肌衰竭的发生。在oh介导的舒张功能障碍的急性期，细胞内Ca2+水平升高和肌丝的改变可能起作用，但这些系统对心肌功能障碍的相对贡献尚不清楚。兔的完整收缩心脏小梁暴露于OH，导致舒张力(Fdia)增加540%。剥皮纤维实验表明，暴露于oh的制剂对Ca2+敏感(EC50: 3.27±0.24×10−6 vs 2.69±0.15×10−6 mol/L, P <0.05)，而最大力发展没有改变。Western blots显示肌钙蛋白T (TnT)被完整的肌钙蛋白I (TnI)水解降解。MDL-28.170阻断calpain I抑制了tnt蛋白水解和Ca2+敏化，但在完整制备中未能预防急性舒张功能障碍。oh诱导的舒张功能障碍在肌浆网完整(540±93%)和药理学阻断(539±77%)的制剂中相似，在l型Ca2+通道拮抗剂维拉帕米的存在下也相似。与此形成鲜明对比的是，KB-R7943抑制反向钠钙交换完全保留了舒张功能。在大鼠心肌中进行其他实验;舒张力的增加与家兔心肌相当，但Ca2+敏感性不变，最大力发展减少。这与TnI的降解有关，但与TnT无关。电镜分析显示OH不会造成不可逆的膜损伤。我们得出结论，oh诱导的急性舒张功能障碍是由Ca2+内流通过钠钙交换器的反向模式引起的。肌钙蛋白的降解似乎是种依赖的，但不有助于急性舒张功能障碍。
{"title":"Hydroxyl Radical-Induced Acute Diastolic Dysfunction Is Due to Calcium Overload via Reverse-Mode Na+-Ca2+ Exchange","authors":"O. Zeitz, A. Maass, Phuc Van Nguyen, Geerd Hensmann, H. Kögler, K. Möller, G. Hasenfuss, P. Janssen","doi":"10.1161/01.RES.0000018625.25212.1E","DOIUrl":"https://doi.org/10.1161/01.RES.0000018625.25212.1E","url":null,"abstract":"Hydroxyl radicals (OH) are involved in the development of reperfusion injury and myocardial failure. In the acute phase of the OH-mediated diastolic dysfunction, increased intracellular Ca2+ levels and alterations of myofilaments may play a role, but the relative contribution of these systems to myocardial dysfunction is unknown. Intact contracting cardiac trabeculae from rabbits were exposed to OH, resulting in an increase in diastolic force (Fdia) by 540%. Skinned fiber experiments revealed that OH-exposed preparations were sensitized for Ca2+ (EC50: 3.27±0.24×10−6 versus 2.69±0.15×10−6 mol/L;P <0.05), whereas maximal force development was unaltered. Western blots showed a proteolytic degradation of troponin T (TnT) with intact troponin I (TnI). Blocking of calpain I by MDL-28.170 inhibited both TnT-proteolysis and Ca2+ sensitization, but failed to prevent the acute diastolic dysfunction in the intact preparation. The OH-induced diastolic dysfunction was similar in preparations with intact (540±93%) and pharmacologically blocked sarcoplasmic reticulum (539±77%), and was also similar in presence of the L-type Ca2+-channel antagonist verapamil. In sharp contrast, inhibition of the reverse-mode sodium-calcium exchange by KB-R7943 preserved diastolic function completely. Additional experiments were performed in rat myocardium; the rise in diastolic force was comparable to rabbit myocardium, but Ca2+ sensitivity was unchanged and maximal force development was reduced. This was associated with a degradation of TnI, but not TnT. Electron microscopic analysis revealed that OH did not cause irreversible membrane damage. We conclude that OH-induced acute diastolic dysfunction is caused by Ca2+ influx via reverse mode of the sodium-calcium exchanger. Degradation of troponins appears to be species-dependent but does not contribute to the acute diastolic dysfunction.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"27 1","pages":"988-995"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76786194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000017622.25365.71
U. Friis, B. Jensen, Shala Sethi, D. Andreasen, P. Hansen, O. Skøtt
We tested the hypothesis that cGMP stimulates renin release through inhibition of the cAMP-specific phosphodiesterase 3 (PDE3) in isolated rat juxtaglomerular (JG) cells. In addition, we assessed the involvement of PDE4 in JG-cell function. JG cells expressed PDE3A and PDE3B, and the PDE3 inhibitor trequinsin increased cellular cAMP content, enhanced forskolin-induced cAMP formation, and stimulated renin release from incubated and superfused JG cells. Trequinsin-mediated stimulation of renin release was inhibited by the permeable protein kinase A antagonist Rp-8-CPT-cAMPS. PDE4C was also expressed, and the PDE4 inhibitor rolipram enhanced cellular cAMP content. Dialysis of single JG cells with cAMP in whole-cell patch-clamp experiments led to concentration-dependent, biphasic changes in cell membrane capacitance (Cm) with a marked increase in Cm at 1 &mgr;mol/L, no net change at 10 &mgr;mol/L, and a decrease at 100 &mgr;mol/L cAMP. cGMP also had a dual effect on Cm at 10-fold higher concentration compared with cAMP. Trequinsin, milrinone, and rolipram mimicked the effect of cAMP on Cm. Trequinsin, cAMP, and cGMP enhanced outward current 2- to 3-fold at positive membrane potentials. The effects of cAMP, cGMP, and trequinsin on Cm and cell currents were abolished by inhibition of protein kinase A with Rp-cAMPs. We conclude that degradation of cAMP by PDE3 and PDE4 contributes to regulation of renin release from JG cells. Our data provide evidence at the cellular level that stimulation of renin release by cGMP involves inhibition of PDE3 resulting in enhanced cAMP formation and activation of the cAMP sensitive protein kinase.
{"title":"Control of Renin Secretion From Rat Juxtaglomerular Cells by cAMP-Specific Phosphodiesterases","authors":"U. Friis, B. Jensen, Shala Sethi, D. Andreasen, P. Hansen, O. Skøtt","doi":"10.1161/01.RES.0000017622.25365.71","DOIUrl":"https://doi.org/10.1161/01.RES.0000017622.25365.71","url":null,"abstract":"We tested the hypothesis that cGMP stimulates renin release through inhibition of the cAMP-specific phosphodiesterase 3 (PDE3) in isolated rat juxtaglomerular (JG) cells. In addition, we assessed the involvement of PDE4 in JG-cell function. JG cells expressed PDE3A and PDE3B, and the PDE3 inhibitor trequinsin increased cellular cAMP content, enhanced forskolin-induced cAMP formation, and stimulated renin release from incubated and superfused JG cells. Trequinsin-mediated stimulation of renin release was inhibited by the permeable protein kinase A antagonist Rp-8-CPT-cAMPS. PDE4C was also expressed, and the PDE4 inhibitor rolipram enhanced cellular cAMP content. Dialysis of single JG cells with cAMP in whole-cell patch-clamp experiments led to concentration-dependent, biphasic changes in cell membrane capacitance (Cm) with a marked increase in Cm at 1 &mgr;mol/L, no net change at 10 &mgr;mol/L, and a decrease at 100 &mgr;mol/L cAMP. cGMP also had a dual effect on Cm at 10-fold higher concentration compared with cAMP. Trequinsin, milrinone, and rolipram mimicked the effect of cAMP on Cm. Trequinsin, cAMP, and cGMP enhanced outward current 2- to 3-fold at positive membrane potentials. The effects of cAMP, cGMP, and trequinsin on Cm and cell currents were abolished by inhibition of protein kinase A with Rp-cAMPs. We conclude that degradation of cAMP by PDE3 and PDE4 contributes to regulation of renin release from JG cells. Our data provide evidence at the cellular level that stimulation of renin release by cGMP involves inhibition of PDE3 resulting in enhanced cAMP formation and activation of the cAMP sensitive protein kinase.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"55 1","pages":"996-1003"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82317701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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