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

Vasodilation and vasoconstriction of small resistance vessels in the coronary microcirculation are key mechanisms for regulating coronary blood flow. This dynamic regulation acts as a reserve system that ensures adequate perfusion under varying physiological conditions and metabolic demands. In the presence of coronary artery stenosis, part of this vasodilatory reserve may already be used, triggered by pressure-flow autoregulation mechanisms that maintain normal blood flow at rest. Fractional flow reserve (FFR), measured during pharmacologically induced maximum vasodilation/hyperemia (typically with adenosine), remains the gold standard for diagnosing coronary artery disease. Computed tomography-derived FFR (CT-FFR) provides noninvasive FFR estimates and is increasingly recommended as a gatekeeper to invasive evaluation. Most current CT-FFR models assume a fixed microvascular response to adenosine, treating vasodilation capacity as constant and optimal for all patients and lesions. Using intracoronary pressure measurements, we quantified how stenosis severity affects the microcirculatory response to adenosine. Based on these findings, we developed a CT-FFR algorithm that incorporates autoregulation. In comparison across 280 lesions, the autoregulation-based model reduced prediction variability (SD = 0.1006 vs. 0.1167, P value = 0.013) and improved the coefficient of determination (R² = 0.398 vs. 0.179) relative to a fixed-response model, using invasive FFR as reference. However, the area under the curve (AUC) remained unchanged. Sensitivity analyses showed that autoregulation effects were minor in lesions with CT-FFR > 0.7. Feature analysis showed that vessel location, patient sex, and heart rate are associated with the microvascular response to adenosine, emphasizing the need to consider these factors in the combined assessment of epicardial and microvascular disease.NEW & NOTEWORTHY We present a novel autoregulation-aware model of microvascular resistance for CT-FFR computations. The model improves prediction accuracy compared with conventional approaches for modeling the hyperemic state. Integration of CCTA-derived anatomy and invasive pressures reveals sex- and territory-dependent microvascular responses to adenosine, highlighting the diagnostic role of combined assessment of epicardial and microvascular disease.

Significant lymphatic structural remodeling and dysfunction have been observed in preclinical models of cardiovascular disease. However, a detailed understanding of the normal structure and distribution of lymphatic vessels (LyVs) in the heart is still lacking. The goal of this study is to define the pattern of LyVs at various cardiac anatomical sites using Prox1-tdTomato lymphatic reporter mice. By light sheet microscopy, we first confirmed the presence of an extensive network of LyVs on the epicardial surface of the ventricles, while minimal signal was detected on the atria. We then evaluated LyV distribution within the heart using cryo- and vibratome sections. To ensure accurate identification of Prox1-tdTomato⁺ LyVs, we performed immunostaining of common lymphatic markers (LYVE1, podoplanin, and VEGFR3). In the ventricles, LyVs were enriched on the epicardium, subepicardial region, and endocardium of the right ventricular septum. We also detected LyVs on the subepicardial surface of the left atrium, within the mitral valve and interatrial septum and near the valves and atrioventricular node (AVN). In addition to LyVs, LYVE1 and PROX1 were expressed by other cell types. LYVE1 was expressed by tissue resident macrophages and a subset of endocardial cells lining the trabeculated regions of the atria and ventricles, and PROX1 was mainly expressed by valvular endothelial cells, endocardial cells lining the interatrial septum and a subset of cells within the AVN. Finally, single-cell RNA sequencing (scRNA-Seq) analysis revealed six subtypes of cardiac lymphatic endothelial cells. Our study serves as a comprehensive resource to facilitate the proper identification of LyVs in the mouse heart.NEW & NOTEWORTHY This is the first study detailing normal lymphatic vessel distribution at various cardiac anatomical sites using a lymphatic reporter mouse model, multiple markers, and modern imaging modalities, providing a blueprint for future studies. We also performed integrated single-cell RNA sequencing (scRNA-Seq) analysis to define the cellular and transcriptional heterogeneity of cardiac lymphatic endothelial cells. Finally, our study underscores the nonspecific nature of lymphatic markers and emphasizes the necessity of using at least two markers to identify lymphatic vessels.

Compared with left ventricular (LV) remodeling in cardiac aging, right ventricular (RV) adaptations to pulmonary arterial (PA) changes are less well characterized. We evaluated CMR-derived indices of RV function and a volume-based surrogate of RV-PA coupling in community-dwelling older adults without cardiovascular disease. Participants underwent cardiac magnetic resonance with assessment of RV volumes (EDV, ESV), function (RVEF, RV global longitudinal strain [RVGLS]), and RV-PA coupling (LV stroke volume/RVESV). An RV-PA ratio >1.5 indicated effective adaptation. We studied 255 participants (54.5% females, 70.8 ± 9.1 yr) with normal biventricular function (mean: LVEF = 65.1 ± 7.5%, RVEF = 64.3 ± 7.0%). RV-PA <1.5 was associated with lower RVEF (56.6% vs. 67.5%, P < 0.001), less negative RVGLS (-28.1% vs. -32.8%, P = 0.007) and higher-indexed RVEDV (73.2 vs. 63.3 mL/m², P < 0.001). Female sex independently predicted more favorable RV indices (better RVGLS and smaller RVESV), whereas higher BMI and older age were associated with larger RVESV. Compared with men, women had higher RVEF and more negative RVGLS, but lower RV stroke volume and peak V̇o₂, and higher RV-PA ratios (2.1 vs. 1.8, P < 0.001). Female sex remained independently associated with higher RV-PA ratio. In healthy, community-dwelling older adults, CMR-derived measures characterize RV function and a surrogate of RV-PA interaction, with women demonstrating more favorable right heart phenotype and higher RV-PA ratios than men within this cohort. These findings highlight sex-related differences in RV adaptation to aging not captured by LV-focused assessment. As a cross-sectional study, they should be interpreted as physiological reference data rather than prognostic.NEW & NOTEWORTHY Our study used cardiovascular magnetic resonance to examine sex-based differences in right ventricular function and right ventricular-pulmonary arterial (RV-PA) coupling in 255 healthy older adults. Women had smaller right ventricular volumes but demonstrated higher ejection fraction, superior myocardial strain, and stronger RV-PA coupling compared with men. These findings highlight distinct hemodynamic adaptations of the aging right heart, suggesting that sex-specific reference values may be needed to differentiate physiological variation from early pathological changes.

Tissue sodium accumulation affects cardiovascular pathophysiology; however, current tissue element trace determination methods show high variability, limiting translational studies. We evaluated within-sample variability and tested whether microwave digestion reduced variability compared with dry ashing and whether flame atomic emission spectrometry (FAES) reduces variability compared with inductively coupled plasma-optical emission spectrometry (ICP-OES). Skin and muscle samples from rats, mice, and humans were divided into three parts and digested separately. Within-subject variability was tested by repeating the microwave digestion workflow on the second and third tissue pieces. Certified reference material (CRM) was used to assess recovery. Agreement between digestion and detection techniques was assessed using Bland-Altman analysis and intraclass correlation coefficients (ICCs). Interassay CVs for the microwave digestion/FAES workflow were 3.3 ± 2.8% for water, 9.1 ± 8.5% for sodium, and 14.9 ± 12.1% for potassium. CRM recovery was 98.9% for sodium and 91.5% for potassium. Dry ashing and microwave digestion agreement was good for sodium (ICC = 0.78) and excellent for potassium (ICC = 0.91). The dry ashing quantified less sodium than microwave digestion (-2.3 ± 23.7%), correlating to tissue weight (r = 0.54, P < 0.001) and negatively to sodium concentration (r = -0.63, P < 0.001). ICP-OES and FAES displayed excellent agreement for both elements (ICC > 0.90). The use of dry ashing and intrasample composition emerged as the primary driver of variability. Microwave digestion reduces variability and bias relative to dry ashing, whereas FAES maintained analytical concordance with ICP-OES, enabling more reproducible, faster, and easier quantification of tissue sodium and potassium in human and rodent studies relevant to cardiovascular physiology.NEW & NOTEWORTHY Tissue sodium is increasingly linked to cardiovascular pathophysiology, yet current measurement methods are slow, costly, and inconsistent. In this study, we quantified the variability of sodium and potassium assessment across human and rodent tissues. We show that ashing contributes to measurement bias, whereas microwave digestion offers a faster, more reproducible, and accessible workflow compared with dry ashing. This approach enables standardized electrolyte analysis to advance cardiovascular research.

S-nitrosoglutathione reductase (GSNOR), a regulator of protein S-nitrosylation (SNO), has been proposed as a longevity protein. GSNOR signaling has been implicated in both the alleviation and exacerbation of aging. In the context of ischemia-reperfusion injury, we previously showed a sex-dependent response to GSNOR inhibition; cardiac damage was alleviated in males and exacerbated in females. Considering sex differences in the incidence of cardiovascular disease with age, we investigated the effect of GSNOR deletion (^-/-) on age-related changes in cardiac function. We performed longitudinal two-dimensional echocardiography measurements in M-mode on male and female, wild-type (WT) and GSNOR^-/- mice at young (3-4 mo), middle (13-15 mo), and old age (18-20 mo). Left ventricular wall thickness and ejection fraction decreased with age in WT mice but were maintained in GSNOR^-/-. Western blot and GSNOR activity assays showed GSNOR activity and expression decreased with age in WT females. Isolated cardiomyocyte force-coupling analysis showed that increasing age was inversely correlated with sarcomere shortening and Ca²⁺ release kinetics in WT males but not GSNOR^-/-. WT females showed slower Ca²⁺ re-uptake after contraction and time to peak sarcomere shortening, but all other parameters were maintained. GSNOR^-/- females exhibited slower Ca²⁺ re-uptake and decreased sarcomere shortening. Proteomic analysis of SNO from females showed increased modification of pyruvate dehydrogenase, E1β, and dihydrolipoamide dehydrogenase in young WT females relative to middle-aged mice. Together, our data suggest that GSNOR deletion is beneficial in males by maintaining cardiac function; although the absence of GSNOR in females removes an age-essential SNO imbalance, which may exacerbate age-related pathology.NEW & NOTEWORTHY GSNOR deficiency appears beneficial to cardiac aging in both sexes, but at the cellular level, we discovered a sex disparity and the potential for underlying cellular dysfunction in female hearts. Taken together, GSNOR deficiency may present a mechanism through which the female heart specifically is at a higher risk of age-related cardiovascular disease and may represent a potential clinical target.

MicroRNAs (miRNAs), short noncoding RNAs that posttranscriptionally regulate gene expression, have emerged as critical regulators of cardiac genes. Although circulating miRNAs have been implicated in cardiovascular disease, their precise functional roles remain poorly understood. Using Drosophila as a model, we applied miRNA sponge technology to competitively inhibit miR-6 (the mammalian homolog, miR-27), enabling us to systematically assess its impact on heart function, morphology, and lifespan. Functional and structural cardiac changes were analyzed with semiautomatic optical heartbeat analysis (SOHA) software and immunohistochemistry. In silico target analysis revealed 149 conserved predicted gene targets shared by this miRNA family, highlighting its potential regulatory scope. Our findings uncover a novel cardioprotective role for miR-6 inhibition, demonstrating that heart-specific miR-6 suppression mitigates age-related changes to heart size and function, significantly extends lifespan, and leads to increased lipid accumulation in cardiomyocytes. Importantly, we observed elevated expression of the conserved target gene low-density lipoprotein receptor-related protein 1 (LRP1) in miR-6-inhibited hearts, and genetic disruption of LRP1 expression in miR-6 inhibition decreased lipid accumulation in the heart. Conservation of miR-27b and LRP1B expression in mammalian cardiac tissue further validates the translational relevance of these findings.NEW & NOTEWORTHY This work establishes miR-6 as a novel regulator of cardiac health, specifically in aging, through its modulation of lipid metabolism, heart function, and longevity. These insights expand our understanding of miRNA-mediated cardiac regulation and provide a foundation for developing miRNA-targeted therapies to combat heart disease and age-related cardiac decline.

Angiogenesis, the formation of new blood vessels from pre-existing ones, is essential for development, tissue repair, and tumorigenesis. As a delicately orchestrated morphogenesis process, angiogenesis is driven by endothelial cell (EC) migration and proliferation in response to environmental signals such as angiogenic factors. Both the environmental signals from non-ECs and their corresponding receptors and downstream pathways in ECs are key for angiogenesis. RNA-binding proteins (RBPs) play a critical role in regulating gene expression posttranscriptionally. Their complex interactions with RNA molecules determine RNA fate, ultimately influencing protein expression and cell behavior. Although RBPs' regulation of gene expression at the posttranscriptional level is relatively understudied in vascular biology, recent studies highlight their significance in modulating angiogenic gene pathways in both ECs and non-ECs. This review summarizes recent findings and identifies knowledge gaps regarding the roles of RBPs in recognizing and regulating both canonical mRNAs and chemically modified mRNAs during angiogenesis, with a focus on molecular mechanisms of how RBPs regulate their target mRNAs.

Exercise training has been shown to reverse cardiac dysfunction in patients and animal models of coronary artery disease; however, the underlying mechanisms have not been fully elucidated. Transmembrane integrins that connect the extracellular matrix (ECM) and intracellular cytoskeleton are important for mechanotransduction in cardiomyocytes. We tested the hypothesis that exercise training would increase cardiac contractile function by modulating the adhesion force between integrins and ECM proteins and subsequent cell signaling and stiffness in myocytes from ischemic porcine hearts. Ameroid occluders were surgically placed around the proximal left circumflex coronary artery of adult Yucatan pigs. Animals subsequently completed either a sedentary or endurance exercise (treadmill run 5 days/wk for 14 wk) protocol, after which myocardium was isolated from nonoccluded and collateral-dependent regions. The collateral-dependent myocardial region exhibited increased fibrosis, inflammatory cytokines, and collagen I and III levels, which were ameliorated with exercise training. Exercise also increased fibronectin and β1 integrin and decreased β3 integrin levels in collateral-dependent myocardium compared with that of sedentary pigs. Atomic force microscopy revealed that an increase in fibronectin-integrin adhesion force was mediated by α₅β₁ and α_vβ₃ integrins in cardiac myocytes of exercise-trained pigs. Exercise training increased mechanical stiffness in cardiomyocytes compared with that in sedentary swine. Fibronectin- and exercise-induced force generation in trabeculae from collateral-dependent myocardium was each decreased by focal adhesion kinase (FAK) inhibition. These data demonstrate that exercise training increases force generation in cardiomyocytes by attenuating inflammation and by promoting fibronectin-mediated FAK activation, suggesting potential targeting of this mechanotransduction pathway for therapeutic development.NEW & NOTEWORTHY Exercise produces cardioprotective effects and reverses cardiac dysfunction, but underlying cellular and molecular mechanisms are not fully identified. This study revealed that endurance exercise increased fibronectin expression in the myocardium of ischemic swine hearts and enhanced myocyte adhesion with α₅β₁ integrin, cell stiffness, and force generation, which was blunted by focal adhesion kinase inhibition. Thus, endurance exercise reverses cardiac dysfunction by promoting fibronectin interactions with integrins supporting this mechanotransduction pathway as a potential therapeutic target.

Sigma receptor agonists are suspected to modulate blood pressure in humans. We investigated how modulation of sigma receptors impacts phenylephrine (PE)-induced contraction in human mesenteric arterial rings obtained from human organ donors. This study also explored the relationship between sigma receptor activation, PE-induced arterial contraction, and the history of the organ donor's alcohol use. The concentration responsiveness of PE-induced arterial contraction was tested using wire myography in the absence and presence of the sigma receptor agonist PRE-084, and the sigma receptor antagonists BD-1047 and SM-21. Sigma receptor-1 expression in the arteries was also investigated using an automated capillary electrophoresis system. The results show that PRE-084 elicited a downward shift in the PE concentration-response curve. Notably, this trend only occurred in arteries from donors with histories of non-/light drinking or moderate drinking (P < 0.05) but not with arteries obtained from donors with histories of heavy or binge drinking. The sigma receptor-1 antagonist BD-1047 elicited an upward shift in the PE concentration-response curve in arteries from non-/light and moderate drinkers but not from heavy drinkers. Interestingly, the sigma receptor-2 antagonist caused an upward shift in the PE concentration-response curve in arteries from all three groups of donors. Notably, sigma receptor-1 protein levels were decreased in arteries from heavy drinkers compared with the other groups. Collectively, the findings suggest that sigma receptors in human arteries may promote relaxation. However, heavy alcohol consumption reduces arterial sigma receptor-1 expression and impairs its ability to modulate contraction.NEW & NOTEWORTHY Activation or inhibition of sigma receptor-1 was found to modulate phenylephrine-induced contraction of isolated mesenteric arteries from human organ donors. However, this effect was impaired in arteries from donors who were heavy alcohol consumers, because the arteries from these individuals had relatively low protein expression of sigma receptor-1. These findings reveal a potential new role of sigma receptor-1 in the control of arterial tone in humans that is modulated by alcohol use.