American journal of physiology. Heart and circulatory physiology最新文献

Sex differences in cardiovascular disease are well documented, with females often considered hormonally protected. However, some differences persist even after menopause, indicating nonhormonal influences. Endothelial dysfunction is an early contributor to cardiovascular disease, with endothelial cell senescence playing a key role. Senescence, an irreversible cell cycle arrest, can be replicative or stress-induced. This study investigates whether sex differences in endothelial senescence exist independent of hormonal influence and vary by stimulus. Senescence was induced by replication or irradiation in female and male human umbilical vein endothelial cells (HUVECs) (up to n = 7 each) cultured under hormone-free conditions. Senescence-associated β-galactosidase (SA-β-Gal) staining; telomere length; quantitative real-time PCR (RT-qPCR) of p21, p14, p16; and crystal violet assays were used to assess senescence. Replicative senescence was analyzed across passages 1-20 and stress-induced senescence 5 days after irradiation. Female HUVECs had a significantly longer replicative lifespan than male cells (P = 0.0012) despite similar proliferation. Telomere attrition occurred faster in male cells (P = 0.0034), with earlier expression of senescence markers. In contrast, after irradiation, female cells exhibited stronger senescence responses, including increased SA-β-Gal staining and elevated p21, p14, and p16 levels. This study identifies sex differences in endothelial cell senescence under hormone-free conditions, pointing to intrinsic cellular factors. Although male cells exhibited earlier senescence under replicative stress, female cells were more vulnerable to stress-induced senescence. Together, these results highlight the importance of sex- and stimulus-specific mechanisms in vascular aging.NEW & NOTEWORTHY This study reveals intrinsic, hormone-independent sex differences in endothelial cell senescence. Female HUVECs exhibit delayed replicative but enhanced stress-induced senescence compared with male cells. These opposing responses highlight that sex-specific mechanisms in vascular aging depend on the type of senescence stimulus. By using hormone-free conditions, the study underscores the importance of intrinsic cellular factors in endothelial biology and suggests that sex should be considered when investigating and targeting vascular aging and disease.

Preeclampsia induces adverse cardiovascular outcomes for both mother and offspring. We established a novel leptin-induced mouse model of preeclampsia that induces hypertension, endothelial dysfunction, and fetal growth restriction, which are collectively ablated by endothelial cell mineralocorticoid receptor (MR) deletion. However, literature lacks preclinical evidence to use MR antagonism for preeclamptic patients. We hypothesize that eplerenone improves blood pressure, vascular function, and fetal outcomes in leptin-infused pregnant mice. We infused timed-pregnant Balb/c mice with saline (sham) or leptin via subcutaneous osmotic minipump and administered vehicle or eplerenone from gestation day (GD) 11-18 and GD15-18. We measured mean arterial blood pressure (BP) via radiotelemetry, vascular function in second-order mesenteric arteries by wire myography, and pup/placental weights on GD18. Eplerenone from GD11-18 ablated leptin-induced increases in BP but independently decreased fetal weight and placental efficiency. Eplerenone increased vascular contractility to phenylephrine and increased mRNA expression of NADPH oxidase (NOX) 1 and 2 in the placentas of pregnant mice in the GD11-18 cohort. We observed in our GD15-18 cohort that eplerenone no longer decreased fetal weight or placental efficiency and there was no increase in contractility to phenylephrine. In conclusion, our data suggest that although eplerenone improves leptin-induced hypertension in pregnant mice, eplerenone reduces fetal weight when administered at mid-, but not late-, gestation in pregnant mice.NEW & NOTEWORTHY There are limited advances in the treatment for preeclampsia. Leptin induces preeclampsia dependent on mineralocorticoid receptor (MR) activation; however, there is little preclinical data on the use of MR antagonists in hypertensive pregnancy. When administered at midgestation in hypertensive mouse pregnancy, eplerenone lowers blood pressure, but increases vasoconstriction in mesenteric arteries and reduces fetal growth. When administered later in pregnancy, eplerenone no longer restricts fetal growth or increases vasoconstriction.

Left ventricular (LV) flow state is associated with unfavorable outcome in patient with severe aortic stenosis. However, there is little information on its impact on long-term prognosis in a population without valvular disease. To examine the impact of low-flow state (LFS) on all-cause mortality in multiethnic population, we analyzed 4,398 asymptomatic participants without clinical cardiovascular disease undergoing cardiac magnetic resonance (CMR) in the multiethnic study of atherosclerosis. LV stroke volume index (SVi), LV ejection fraction (LVEF), and myocardial contraction fraction (MCF) were measured. LV flow states were classified as normal flow state (NFS: SVi > 35 mL/m²), low-flow state (LFS, 30-34 mL/m²), and very low-flow state (VLFS: SVi < 30 mL/m²). Clinical data were collected at enrollment. Participants were followed up for a median of 14.2 yr. All-cause and cardiovascular disease mortalities were used as primary endpoints. All-cause mortality was 16.2%, and cardiovascular disease mortality was 3.5%. VLFS and LFS groups had more cardiovascular risk factors and lower cardiac performance than NFS. The relationship between all-cause mortality and SVi was "L-shape" with the "breakpoint" at 33.5 mL/m² for a statistical significance (P = 0.009). All-cause mortality was significantly associated with LFS after adjusted for age, sex, LVEF, and LV mass index with hazard ratio (HR) 1.81, 95% confidence interval (CI): 1.31-2.49 for VLF and HR: 1.21, 95% CI: 0.95-1.54 for LFS with overall P value 0.001. The highest cardiovascular disease mortality was seen in VLFS. LFS was significantly associated with increased all-cause mortality despite normal LVEF and no valvular disease.NEW & NOTEWORTHY This is the first study demonstrating that low-flow state (LFS) has a significant impact on mortality in multiethnic study of atherosclerosis (MESA) participants with no valvular disease. The study may have a clinical implication since LFS is commonly present in multiethnic population. The current study provides new information on clinical characteristics and myocardial performance of LFS suggesting that further prospective studies to determine whether targeting modifiable risk factors for cardiovascular disease and metabolic syndrome would have any favorable impact on LFS.

Wound healing after myocardial infarction (MI) is a dynamic and multifaceted process that links the molecular alterations induced by or in response to prolonged ischemia with structural and physiological changes to the damaged myocardium. Changes, at the tissue level, are driven by a complex intersection of cellular and molecular mechanisms that operate along a classic wound healing paradigm as an attempt to repair the damaged myocardium and restore cardiac physiology. Maladaptive healing prevents a return to the original homeostasis, rather yielding a myocardium reset to a new homeostatic status that can lead to heart failure due to compromised contractility, increased chamber dilation, and cardiac fibrosis or due to sudden cardiac death resulting from arrhythmias. This review summarizes our current knowledge of how key inflammatory drivers in the myocardium (cardiomyocytes, neutrophils, monocytes/macrophages, fibroblasts, and vascular endothelial cells) respond to molecular signals including cytokines, growth factors, and proteases to coordinate the wound healing process in the mouse model of MI. We also identify knowledge gaps that remain in our understanding of cardiac remodeling that are opportunities for future examinations.

Accumulating evidence from human clinical cohorts and animal models indicates that DNA damage plays a pivotal role in the initiation, progression, and severity of cardiomyopathy subtypes. Cardiomyocytes are exposed to continuous mechanical stress due to persistent contractile activity, and this stress is transduced to the nucleus, rendering CMs vulnerable to mechano-transduced DNA damage. CMs are also vulnerable to oxidative stress-induced DNA damage. The DNA damage response (DDR) constitutes a cellular program that integrates lesion sensors, signal transducers, downstream effectors, and repair machineries, thereby governing cell cycle progression and other cell fate decisions. DDR responses have been studied in proliferating cells, whereas adult CMs are withdrawn from the cell cycle, suggesting distinct DDR mechanisms and outcomes may occur in CMs. Although transient DDR activation helps preserve genomic stability in CMs, sustained activation contributes to maladaptive cardiac remodeling, functional decline, and disease progression. Several key DDR components have been identified as potential therapeutic targets, with their inhibition demonstrating cardioprotective effects in various cardiomyopathy models. Moreover, a growing number of novel pathways have emerged as promising avenues for targeting DNA damage and repair signaling in cardiomyopathy. In this review, we discussed molecular mechanisms by which DNA damage and DDR contribute to the onset and progression of cardiomyopathy, and highlight emerging therapeutic strategies aimed at modulating DNA damage and repair pathways to improve cardiac function and clinical outcomes. Understanding how these pathways intersect with cardiomyocyte biology will be essential for translating bench discoveries into durable therapies for patients with cardiomyopathy and heart failure.

Inbred C57BL/6 mice are the most widely used laboratory mice in biomedical research. There are two C57BL/6 substrains, C57BL/6J and C57BL/6N, that are often used interchangeably incorrectly. We sought to examine vascular function in C57BL/6J and C57BL/6N mice. We observed lower systolic blood pressure and aortic stiffness in C57BL/6N versus C57BL/6J mice. Although acetylcholine-mediated vasodilation was similar between C57BL/6 substrains, flow-mediated vasodilation was greater in C57BL/6N versus C57BL/6J mice. Aortic structural characteristics were also similar between C57BL/6 substrains. These findings indicate distinct differences in vascular function between C57BL/6 substrains, indicating greater vascular function in C57BL/6N mice. To determine the effect of inbreeding on vascular function in C57BL/6J or C57BL/6N mice, we also measured vascular function in UM-HET3 mice, an outbred genetically diverse strain derived from the C57BL/6 strain. In general, UM-HET3 mice had greater vascular function than either C57BL/6 substrain, demonstrated by lower aortic stiffness, aortic medial cross-sectional area, and aortic collagen content and greater aortic elastin content, acetylcholine-mediated vasodilation, and flow-mediated vasodilation. Notably, systolic blood pressure in C57BL/6N mice was also lower than UM-HET3 mice, whereas aortic elastin content and flow-mediated vasodilation were similar between C57BL/6N and UM-HET3 mice. Importantly, greater vascular function in UM-HET3 mice was not accompanied by greater measurement variability, as coefficient of variation across all measurements was similar between strains. These findings suggest that the greater vascular function in UM-HET3 mice does not come at the expense of measurement variability, making them a viable alternative to inbred mice in biomedical research.NEW & NOTEWORTHY We observed major vascular physiological differences between C57BL/6J and C57BL/6N mice, indicating C57BL/6N mice have greater vascular function. However, in comparison to either C57BL/6 substrain, outbred, genetically diverse UM-HET3 mice have a greater vascular function characterized by lower aortic stiffness and greater endothelial-dependent dilation. A greater vascular function in UM-HET3 mice was not accompanied by more measurement variability, as coefficient of variation across measurements was similar between strains.

The use of comprehensive unbiased proteomic evaluations coupled with physiological and clinical insight offers the possibility to enhance our understanding of disease mechanisms and identify potential biomarkers for diagnosis and prognosis of cardiovascular disease. In this methods and resources article, we present the methodologies used for a workflow leveraging a high-throughput, large-scale mass spectrometry-based technology for label-free quantitative proteomic profiling coupled with physiological and clinical assessment. Using this approach, we analyzed a total of 505 plasma samples at baseline and 1- and 2-yr follow-up from patients enrolled in the Non-Invasive Treatment of Abdominal Aortic Aneurysm Clinical Trial. We successfully identified a dataset comprising over 1,000 distinct proteins. Collecting samples longitudinally provides built-in validation, allowing for direct comparisons within the same patient over time. We provide a comprehensive collection and analytical data plan tailored for such a large dataset, which encompasses data acceptance criteria, integrity checks, and database validation. We also provide methods on statistical testing, temporal cross validation, and biological and clinical validation. This resource outlines a template for similar experiments and development of a robust statistical analysis plan that will limit false positive and false negative identifications to focus on true protein changes that may serve as diagnostic or prognostic indicators.NEW & NOTEWORTHY We describe methods for developing a high-throughput, label-free quantitative proteomics workflow integrated with physiological and clinical assessments to investigate cardiovascular disease mechanisms and identify potential biomarkers. This resource outlines a validated, longitudinal plasma proteomics pipeline-including data quality controls, statistical testing, and biological validation-applied to over 500 samples from the N-TA³CT trial, offering a reproducible framework for future biomarker discovery studies.

The present study investigates the impact of intraluminal valves on lymph transport in rat diaphragmatic collecting vessels, with the aim of clarifying their role in intrinsically driven lymph flow. Using ex vivo fluorescent microsphere tracking and micropuncture techniques, lymph flow, pressure gradients, and hydraulic resistance were quantified in valved and nonvalved segments. Key findings revealed that valves significantly increased lymph velocity (approximately 1,617 µm/s) through their narrower functional section (∼14.4% of vessel cross section) compared with nonvalved segments (∼210 µm/s). The presence of valves required higher pressure gradients (4.15 ± 0.57 cmH₂O vs. 2.16 ± 0.27 cmH₂O in nonvalved segments) but markedly increased net lymph flow (68.0 ± 4.2% vs. 45.7 ± 3.7% of forward flow across valved and nonvalved tracts, respectively) by limiting reverse movement even if biased toward an open state. Despite increasing hydraulic resistance, lymph flow remained laminar, and valves optimized net lymph progression, particularly in larger vessels, where the ratio of net flow to forward flow was independent of vessel size. These results quantify and highlight the pivotal role of intraluminal valves in facilitating efficient, unidirectional net lymph transport, even under low-pressure, oscillatory flow conditions, by adapting to the unique hydraulic properties of the diaphragmatic lymphatic network.NEW & NOTEWORTHY This work quantifies the effect that intraluminal valves exert onto the intrinsic lymph flow in an ex vivo preparation of rat diaphragm. By means of particle tracking analysis and intraluminal hydraulic pressure measurements, the added pressure gradient due to the valve, its functional section and the positive effect on net lymph flow have been carefully measured in a quasiphysiological state, revealing that the open-biased state of the valve is the key to net lymph progression.

Heart failure (HF) with preserved ejection fraction (HFpEF) comprises heterogeneous clinical phenotypes and variable comorbidities. Recent two-hit translational animal models, including the hypertensive, nitrosative-stressed mice fed with high-fat diet and l-N^G-nitroarginine methyl ester (HFD + l-NAME) and the obese-diabetic leptin receptor-deficient db/db mice with excess aldosterone (db/db + Aldo), may phenocopy select subgroups of HFpEF. We systematically compared mechanisms of excitation-contraction coupling (ECC), electrophysiology, and gene transcription in these preclinical HFpEF models and between sexes, including morphometry, echocardiography, cellular electrophysiology, intracellular Ca²⁺ imaging, and RNA-sequencing. The multiorgan HFpEF phenotype showed key differences between the two models: db/db + Aldo mice were markedly obese, had severe hyperglycemia and hepatomegaly, whereas male HFD + l-NAME mice had more pronounced cardiac hypertrophy. Diastolic dysfunction (quantified as echocardiographic E/e') was more severe in db/db + Aldo mice and worse in females, whereas females showed milder diastolic dysfunction in HFD + l-NAME. Marked proarrhythmic action potential (AP) changes (prolonged AP duration, increased short-term variability, and reduced alternans threshold) occurred in db/db + Aldo (in both sexes), whereas these AP changes were less severe in male HFD + l-NAME and absent in female HFD + l-NAME. In line with these findings, differential ionic current and Ca²⁺ handling changes occurred between these two HFpEF models and between sexes. RNA-sequencing revealed highly distinctive gene expression profiles between HFpEF models. We conclude that marked differences exist in cardiomyocyte ECC, electrophysiology, and gene expression between HFD + l-NAME and db/db + Aldo mice and between sexes. This indicates that a combination of translational HFpEF models that mimic select HFpEF sub-phenogroups are critical to better understand HFpEF mechanisms for therapeutic drug development.NEW & NOTEWORTHY Excitation-Ca²⁺ signaling-contraction coupling (ECC) mechanisms are fundamental to heart function. ECC mechanisms are differentially altered in murine models of heart failure with preserved ejection fraction (HFpEF) by dominant disease pathology and sex. Diastolic dysfunction is more pronounced in diabetic-obese HFpEF mice (worse in females) than in hypertensive-obese HFpEF mice (female sex is protective). Diabetic-obese mice and primarily hypertensive-obese HFpEF mice exhibit differential ECC alterations and largely distinctive transcription changes, providing mechanistic insights into HFpEF sub-phenogroups.