bluuebunny/crossref_metadata_2025 huggingface dataset:
Smyd5 Regulates Hypertrophic Growth in the Heart
Authors: Anderson Alexa , Miller Mickey , Wang Li , Franklin Sarah
Published: November 2023

Heart disease is the most financially debilitating and fatal disease between both men and women in the United States. Heart failure is defined as the point at which the heart's ability to function declines, due to overexertion, and can no longer sufficiently pump blood to vital organs throughout the body. While there are different forms of heart disease the pathophysiology of these is largely conserved: the heart compensates for an increased work load by undergoing hypertrophic growth and ultimately progresses onto heart failure. The Smyd family of histone methyltransferases has been studied for their involvement in cell growth during development and disease and is thought to accomplish this by regulating gene expression through histone methylation. While the roles of Smyd1, 2, and 3 are beginning to be defined, the remaining two family members, Smyd4 and 5, are virtually uncharacterized. My hypothesis is that Smyd5 is involved in inhibiting hypertrophic growth in the myocardium, however, its role in the heart is completely unknown. To determine the function of Smyd5, we generated constitutive and inducible, cardiac‐specific Smyd5 knockout mice and have characterized their cardiac phenotype under basal conditions and after stress (pressure‐overload hypertrophy and isoproterenol infusion). When compared to wild type mice, these animals display elevated heart weight/body ratios and left ventricular wall thickening as well as increased fibrosis and changes in fetal gene expression normally detected in cardiac hypertrophy. In addition knockout of Smyd5 significantly reduces methylation of lysine 20 on histone H4, suggesting a mechanistic basis for this phenotype. Together, our results show that although Smyd5 is dispensable for cardiac development, it is a critical regulator of hypertrophic cell growth and pathologic gene expression in the cardiomyocyte and highlights a novel role for this histone methyltransferase in the myocardium.

Support or Funding Information

ACCESS, BioURP, APS (UGREF), UROP, CVRTI
Dioscin improves heart function by increasing sodium influx via NCX in rat cardiomyocytes
Authors: Yin Yongqiang , Cong Tianshen , Yang Fan , Han Yu , Wen Ke , Kang Yi , Lou Jianshi
Published: November 2023

Objective

Dioscin (Dio) is widely used for the treatment of ischemic heart disease in China. The molecular mechanism underlying the inotropic effects of Dio, however, remains poorly understood.

Methods and Results

Left ventricle contractile function was measured using the Langendorff non‐recirculating mode of isolated rat heart perfusion. Effects of Dio on cardiac function were assessed by measuring left ventricular systolic pressure (LVSP) and left ventricular end diastolic pressure (LVEDP) as well as the peak rate of rise/fall of left ventricular pressure (±dP/dtmax), in absence or presence of a sodium‐calcium exchanger inhibitor SEA0400. Our ex vivo data show that within the concentrations of 0.1–1μmol/L, Dio significantly increased the LVSP and +dP/dtmax, and these effects were significantly antagonized by 1 μmol·L−1 SEA0400. Furthermore, we investigated the effect of Dio on sodium current (INa) and L‐type calcium current (ICa,L). Intriguingly, the ICa,L was found to be inhibited by Dio, while the INa was augmented by Dio. The effect of Dio on contractile function and ICa,L appears to be contradictory. Therefore, we assessed the effect of Dio on the [Ca2+]i in H9c2 cells. Dio significantly increases the relative fluorescence intensity of intracellular calcium (n=8, P<0.01 vs control), which was partially attenuated by either SEA0400 or calcium‐free or sodium‐free extracellular fluid. Mitochondrial membrane potential was further detected with multifunctional microplate reader in order to determine whether Dio causes mitochondrial injuries. Our data show that Dio barely affected the mitochondrial membrane potential at the concentration of 0.1–1 μmol·L−1, while 10 μmol·L−1 dioscin results in a slight decrease in the mitochondrial membrane potential.

Conclusion

Our results demonstrate that Dio exerts the positive inotropic effect through elevating [Ca2+]i and increasing sodium influx and sodium‐calcium exchange via the Na+/Ca2+ exchanger (NCX) in rat cardiomyocytes.

Support or Funding Information

Supported by Youth Project of Tianjin Natural Fundation (14JCQNJC13700) to Yongqiang Yin
Single‐Beat Estimation of Isovolumic Maximum Pressure can Predict Left Ventricular Contractility in Rats
Authors: Tohyama Takeshi , Saku Keita , Nishikawa Takuya , Oga Yasuhiro , Kishi Takuya , Sunagawa Kenji
Published: November 2023

Background

Although the end‐systolic elastance (Ees), the slope of the end‐systolic pressure‐volume (PV) relationship, has been used as a load insensitive index of cardiac contractility, technical difficulties in measuring left ventricular (LV) volume under various loading conditions prevent its wide clinical acceptance. In theory, if we can estimate the isovolumic maximum pressure (Pmax) for a given end‐diastolic volume, the slope of the line drawn from the Pmax to the left upper corner of a single PV loop (Fig. 1) gives Ees. Since various clinical approaches allow us to depict PV loops or their surrogates, we can clinically predict Ees once we can estimate Pmax. Thus, in this study, we developed a method to estimate Pmax from a single LVP and predicted Ees in rats under various systolic functions. We assumed that the waveform of ejecting LVP during the isovolumic contraction phase is a scaled version of the isovolumic LVP in time and amplitude.

Methods

In 5 urethane‐anesthetized rats, we inserted a 2F Millar catheter into LV. We attached a flow probe around the ascending aorta. We measured ejecting LVP and isovolumic LVP by cross clamping the ascending aorta under the baseline condition, dobutamine infusion (5 μg/kg/min) or landiolol infusion (100 μg/kg/min). We digitized both LVP and aortic flow at 1000 Hz. We extracted the standard isovolumic LVP from multiple isovolumic contractions (327 waveforms). To eliminate the noise and phase distortion associated with numerical time derivatives of LVP, we approximated LVP by Fourier series expansion and algebraically derived their first and second time derivatives. On the basis of the unique waveform during isovolumic contraction phase, taking the ratio of the first derivative of ejecting LVP to that of the standard LVP at the moment of the maximum second derivative and scaling Pmax of standard LVP by the ratio yields the Pmax estimation. Ees was calculated from the tangential line drawn from the Pmax at end‐diastolic volume to the end‐systolic point of a single PV loop.

Results

The estimated Pmax matched reasonably well with measured over the wide range of LV contractility (Y = 1.16 × − 9.71, r2=0.918, Fig. 2). Dobutamine significantly increased Ees, while landiolol decreased it (vehicle; 532.5±152.4 mmHg/ml, dobutamine; 728.5±178.7 mmHg/ml, landiolol; 186.1±111.4 mmHg/ml, p<0.05, Fig. 3).

Conclusions

Our proposed method accurately estimated Pmax from a single LVP. This is to say that we validated that the waveform of ejecting LVP during the isovolumic contraction phase is indeed a scaled version of the isovolumic LVP in time and amplitude. This approach would broaden the clinical applicability of Ees for assessing systolic function, therapeutic response and eventually managing patients with heart failure.
Mitigation of Diazinon‐induced cardiovascular and renal dysfunction by Gallic acid
Authors: Ajibade Tayo , Oyagbemi Ademola A. , Omobowale Temidayo O , Olowu Ebunoluwa R
Published: November 2023

The link between environmental pollutants and cardiovascular dysfunction had been neglected for the decades. However, new insights into the pathology and the consequences of these killers are being studied. In this study, rats were divided into four groups each containing 10 rats. Rats in group one served as controls and were administered normal saline, whereas rats in group two were orally gavaged with 3 mg/kg of Diazinon (DZN) alone for twenty one consecutive days. The rats in groups 3 and 4 were administered with 60 mg/kg and 120 mg/kg Gallic acid (GA) in addition to DZN for twenty one consecutive days. Exposure of rats to Diazinon significantly (p <0.05) reduced the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione‐S‐transferase (GST) activities and reduced glutathione (GSH) content. Also, malondialdehyde, hydrogen peroxide (H2O2) generated and nitric oxide (NO) contents were also significantly (p <0.05) elevated following DZN exposure. DZN also caused significant (p <0.05) decreased heart rate and QT prolongation. Haematological analysis revealed significant reduction (p< 0.05) in packed cell volume (PCV), Haemoglobin concentration (Hb), red blood cell (RBC) count, total white blood cell counts of rats administered only DZN. Observations in this study suggest a protective modulatory role for Gallic acid in Diazinon‐induced anaemia and associated cardiovascular dysfunction in rats. Treatment with Gallic acid reversed the aforementioned oxidative stress markers, increased antioxidant defence system and the deleterious effects on haematological parameters of rats. Pathology of the heart and kidney was also restored.
A Support Vector Machine to Predict Impending Pre‐Syncope from Hemodynamic Derived Signals During Progressive Central Hypovolemia
Authors: van der Ster Jacob P. , Bennis Frank C. , Stok Wim J. , Westerhof Berend E. , Settels Jos J. , Hatib Feras , van Lieshout Johannes J.
Published: November 2023

Background

Hypovolemic shock is characterized by a critically reduced central blood volume (CBV). The heart rate and blood pressure responses to a reduced CBV do not predict onset of hypovolemic shock. We hypothesized that a machine learning model detects subtle changes and patterns within hemodynamic signals that predict impending pre‐syncope as an expression of a critically reduced CBV.

Methods

In 33 healthy subjects we provoked pre‐syncope by reducing CBV using continuous lower body negative pressure. We extracted information from the arterial pressure wave and used it as model input. Next to blood pressure and heart rate, we introduced a new set of blood pressure wave features. We trained a support vector machine to predict time remaining till pre‐syncope using leave‐one‐out methods. We expressed the model performance as absolute error and a squared correlation coefficient (r2).

Results

In 72% of the predictions the model followed the decreasing time remaining towards pre‐syncope. Mean r2 was 0.43 [0.13 – 0.64]. In 13 subjects the model predicted pre‐syncope with an median error of −49 seconds [−312 −27].

Conclusion

The model detects a trend towards pre‐syncope conforming to a worsening condition of subjects in a controlled progressive hypovolemia setting, but cannot pinpoint the onset of pre‐syncope exactly. Future research may reveal the most valuable input feature and allow for testing current models during real hemorrhage.

Support or Funding Information

Educational grant supplied by Edwards Lifesciences.
Role of leptin in coronary vascular dysfunction and proliferation
Authors: Noblet Jillian Nicole , Goodwill Adam G , Sassoon Daniel J , Kiel Alex M , Tune Johnathan D
Published: November 2023

The purpose of this investigation was to test the hypothesis that leptin augments vasoconstriction and impairs dilation via a Rho kinase‐dependent pathway and promotes proliferation of coronary smooth muscle. Coronary arteries from domestic swine were cleaned of surrounding tissue and incubated with/without leptin (30 ng/mL) for 30 min. Leptin administration significantly augmented contractile responses to KCl (10 – 60 mM), with active tension development increased by ~1.3 g at doses >40mM, and reduced maximal vasodilation to adenosine (30 μM) ~18% compared to untreated controls. To examine the extent to which longer‐term exposure to leptin influences coronary vascular reactivity, arteries were placed in organ culture for 3 days. Following incubation in serum‐free media, leptin treatment significantly augmented overall active tension development to KCl (10 – 60 mM), with an average increase of ~2.0 g at doses >40 mM, and reduced maximal vasodilation to adenosine (30 μM) ~50% compared to untreated controls. The acute and chronic effects of leptin administration on maximal KCl (60 mM) contractions were essentially abolished in the presence of the Rho kinase inhibitor, fasudil (1 μM). Short‐term leptin exposure significantly increased the level of Rho kinase activity, while no difference in Rho kinase (Rock‐2) protein abundance was detected. In contrast, long‐term leptin administration in cultured arteries significantly increased the abundance of Rock‐2 protein, while no difference in Rho kinase activity level was detected. Global proteomic assessment of arteries cultured (3 days) in the presence or absence of leptin (30 ng/mL) revealed significant alterations in the coronary artery proteome and Ingenuity Pathway Analysis identified associations between leptin treatment and numerous cellular processes, namely cellular growth and proliferation (35 proteins). To assess the effects of leptin on vascular smooth muscle proliferation, additional studies were conducted in which coronary arteries were cultured in serum‐containing media with/without leptin (30 ng/mL) for 2 or 8 days. 5‐Bromo‐2′‐deoxyuridine (BrdU) staining revealed a significantly higher percentage of BrdU‐positive nuclei in leptin treated arteries (~10%) compared to untreated controls at both time points. Taken together, data from this investigation indicate that leptin alters coronary smooth muscle reactivity and potentiates contraction via a Rho kinase‐dependent pathway. Additionally, these findings support the potential for leptin to modulate a key network of pathways that promote vascular smooth muscle proliferation.

Support or Funding Information

Indiana University Health, Indiana University School of Medicine Strategic Research Initiative (CECARE); HL117620 (J.D. Tune‐Mather); TL1 TR001107 and UL TR001108 (A. Shekhar).
Osteoprotegerin and Receptor Activator of Nuclear Factor‐κB Ligand Alter Intracellular Ca2+ Handling in Coronary Smooth Muscle Cells in an In Vitro Model of Coronary Artery Calcification
Authors: Badin Jill K. , Sturek Michael
Published: November 2023

Metabolic syndrome (MetS) increases the risk of adverse cardiovascular events such as arterial calcification and injury. In response to this MetS‐induced injury, smooth muscle cells often dedifferentiate into an osteoblast‐like phenotype that is associated with augmented expression of certain osteogenic factors, including osteoprotegerin (OPG) and receptor activator of nuclear factor‐κB ligand (RANKL). These secreted proteins have autocrine and paracrine effects in the vasculature and several studies indicate that OPG confers protection against and RANKL exacerbates vascular calcification. We investigated the effects of OPG and RANKL on calcium handling in coronary smooth muscle (CSM) in OPG‐conferred protection and RANKL‐induced vascular calcification. Porcine coronary arteries were cultured in DMEM with either OPG (10 ng/mL) or RANKL (3.0 pmol/L) in normal glucose (100 mg/dL) and high glucose (180 mg/dL). After up to ten days in culture, arterial rings were either fixed for histological analysis or CSM cells were dispersed enzymatically for assessment of sarco‐endoplasmic reticulum Ca2+‐ATPase (SERCA) and voltage‐gated Ca2+ channel (VGCC) activity with imaging of fura‐2 fluorescence. Cells from both OPG‐treated and RANKL‐treated arteries demonstrated increased Ca2+ entry following activation of VGCCs with 80 mM K+. Release of the sarcoplasmic reticulum (SR) Ca2+ store with caffeine revealed an elevated SR Ca2+ store in OPG‐treated arteries, while the SR Ca2+ store was decreased with RANKL treatment. Histological analysis revealed a lack of macrocalcification in all samples. Overall, the most profound effects observed were OPG‐induced increase and RANKL‐induced decrease in SR Ca2+ store, which may provide insight into the differential effects of OPG and RANKL on CSM.

Support or Funding Information

NIH HL125385, IUSM CECARE
Muscarinic agonist carbachol restores insulin secretion and abolishes type 2 diabetes‐like condition in Wolframin1 deficient mice in glucose tolerance test
Authors: Loomets Maarja , Reimets Riin , Plaas Mario , Vasar Eero
Published: November 2023

Mutations in WFS1 gene cause autosomal recessive disorder Wolfram syndrome (WS). One of the first hallmarks of WS is diabetes mellitus. Impairment of glucose metabolism is also present in Wfs1‐deficient mice. While homozygous mutations in Wfs1 cause WS, GWAS studies have shown that heterozygous Wfs1 mutation carriers have increased risk for development of type 2 diabetes. Therefore, in this study, first and second phase insulin secretion was investigated, using glucose tolerance test, muscarinic receptor agonist carbachol and ELISA. Intracellular calcium measurements in single beta‐cells were performed, using cell permeant calcium indicator Fluo‐4 AM. Results of study show that impaired insulin secretion can be managed by evoking insulin release via muscarinic pathway, using carbachol. Although there seems not to be notable differences in the second phase insulin secretion between wild‐type and heterozygous littermates, first phase secretion in heterozygous animals is delayed and this deficit is possibly related to the delayed calcium response in beta‐cells. Altogether, these results show that Wfs1 mutations cause impairment of insulin release in heterozygous animals, the first definite hallmark of type 2 diabetes.
Caveolin‐3 expression is increased in anthracycline‐induced heart failure in rabbits
Authors: Ichikawa Yasuhiro , Zemlic‐Harpf Alice , Hammond Kirk H , McKirnan Dan M , Patel Hemal H , Roth David M
Published: November 2023

Introduction

Anthracyclines, such as daunorubicin, are widely used anticancer drugs. Anthracyclines are cardiotoxic and induce development of heart failure during chemotherapy. Caveolins are structural proteins in cell membranes that bind, organize and regulate receptors and signaling molecules. Caveolin‐3, a muscle specific subtype of caveolin, is highly expressed in the heart and is involved in protection of the heart from cardiac stress. In previous reports, left ventricular (LV) caveolin protein expression is decreased in failing hearts after myocardial infarction; however, the effect of anthracycline‐induced heart failure on caveolin expression is not known. We tested the hypothesis that daunorubicin modulates caveolin expression in the heart.

Methods

New Zealand rabbits were given daunorubicin (3mg/kg, iv) weekly for 8–11 weeks to induce heart failure. LV systolic function was followed using echocardiography and LV fractional shortening (FS) and ejection fraction (EF) were measured. When the LVFS was under 20% (average; 9.0 weeks) heart tissue was collected and divided into 3 parts (LV, intraventricular septum (IVS), right ventricle (RV)). The heart tissue was homogenized and western blot was performed to measure caveolin protein expression.

Results

Daunorubicin treatment (Dau) resulted in progressive and significant decline of LVFS (Control; 32.4% (n=8) vs Dau; 15.9% (n=6), P<0.001) and EF (Control; 69.1% vs Dau; 38.2%, P<0.001) at the end of study. LV end diastolic dimension in Dau was significantly dilated compared to control group (Control; 16.2 mm vs Dau; 19.2 mm, P<0.05). In control hearts, caveolin‐3 expression in RV was higher than in LV or IVS (2.0 and 1.9 ‐fold vs. LV and IVS, respectively, P<0.01, n=6); however, no significant difference in caveolin‐1 expression was observed in the three regions. In heart failure induced by daunorubicin, caveolin‐3 expression was increased in LV, IVS and RV compared to control tissues (2.8, 2.4 and 2.6‐fold vs. control LV, IVS and RV, P<0.05, n=6, respectively) with no change in caveolin‐1 expression.

Conclusions

These results suggest that in heart failure induced by daunorubicin caveolin‐3 expression is increased in the rabbit heart. The pathophysiological role for caveolin‐3 in daunorubicin‐induced heart failure remains to be determined.
Endothelin‐B Receptor Responses in Young and Postmenopausal Women
Authors: Kuczmarski Andrew , Sebzda Kelly N , Mraz Stephanie N , Wenner Megan M
Published: November 2023

Cardiovascular disease (CVD) is the leading cause of the death in women, and postmenopausal women (PMW) are at an increased risk for developing CVD. Endothelin‐1 (ET‐1) contributes to age‐related endothelial dysfunction in men via the ETA receptor. However, there are sex differences in ET‐1 regulation of vascular function, and ETB receptors are influenced by fluctuations in ovarian hormones.

PURPOSE

The purpose of this study was to test the hypothesis that ETB receptors contribute to impaired microvascular function in PMW.

METHODS

We measured skin blood flow (SkBF) in 11 young women (YW; 22±1 years, 22±1 kg/m2) and 10 PMW (58±2 years, 24±1 kg/m2) using laser Doppler flowmetry during microdialysis perfusions of lactated Ringer's (control), an ETB receptor antagonist (BQ‐788, 300nM), and an ETA receptor antagonist (BQ‐123, 500 nM). We utilized local skin heating (42°C) to induce microvascular vasodilation, followed by perfusion of sodium nitroprusside (28mM) to elicit maximal dilation. Mean arterial blood pressure (MAP) was measured throughout. Cutaneous vascular conductance (CVC) was calculated as SkBF/MAP during the plateau established during local heating, and expressed as a percent of maximal dilation. Unpaired t‐tests were used to compare variables between YW and PMW.

RESULTS

Resting MAP was higher in PMW (93±2 mmHg) compared to YW (80±2 mmHg; P<0.05). Vasodilatory responses to local heating (control site) tended to be lower in PMW (YW: 91±2 vs. PMW: 81±5 CVC % max; P=0.12). ETB receptor blockade tended to decrease cutaneous vasodilation in YW (control: 91±2 vs. BQ‐788: 85±3 CVC % max; P=0.08), but tended to enhanced vasodilation in PMW (control: 81±5 vs. BQ‐788: 92±1 CVC % max; P=0.08). ETA receptor blockade had minimal effect in YW (control: 91±2 vs. BQ‐123: 92±2 CVC % max; P=0.35), but tended to increase cutaneous vasodilation in PMW (control: 81±5 vs. BQ‐123: 90±2 CVC % max; P=0.11).

CONCLUSION

ETB receptors appear to mediate vasodilation in YW. However, microvascular vasodilation is blunted in PMW, possibly due to greater ETB and ETA mediated vasoconstriction.

Support or Funding Information

Supported by NIH Grant U54 GM 104941 01A1 and University of Delaware Research Foundation.
Within‐Day Test‐Restest Reliability of the Single Passive Leg Movement Technique: Evidence of Clinical Utility
Authors: Broxterman Ryan M. , Groot H. Jonathan , Rossman Matthew J. , Garten Ryan S. , Venturelli Massimo , Kwon Oh‐Sung , Hydren Jay R. , Gifford Jayson R. , Richardson Russell S.
Published: November 2023

Passive leg movement (PLM) is emerging as a potentially better assessment of nitric oxide (NO)‐mediated vascular function than brachial artery flow‐mediated dilation, as it elicits a robust NO‐mediated increase in both leg vascular conductance (LVC) and leg blood flow (LBF). Typically, PLM is conducted with continuous movements spanning one to two minutes, with the assessment of alterations in LVC. However, single movement PLM with the assessment of alterations in LBF is more appealing as a clinical technique due to the relative ease of administration and minimal central hemodynamic effects. The reproducibility of the evoked physiological responses from single PLM is important for both clinical and research interpretation, but is currently unknown. Therefore, the current study investigated the within‐day test‐retest reliability of the hemodynamic responses elicited by single PLM. In nine subjects (7 men and 2 women), three single PLM trials were performed within the same visit, while second‐by‐second measurements of the central and peripheral hemodynamic responses were acquired with finger photoplethysmography and Doppler ultrasound, respectively. The peak change in LBF (ΔLBFpeak) was not significantly different across the three trials (Mean ± SD; Trial 1: 702.5 ± 483.3; Trial 2: 685.7 ± 421.9; Trial 3: 626.2 ± 383.0 ml min−1, p = 0.77). The intra‐class correlation coefficient (ICC) for these trials was 0.73 (p < 0.0001), the Cronbach's Alpha 0.88, and the coefficient of variation (CV) 34.3 ± 23.3 %. The ΔLBFpeak was not significantly different when the two most similar trials of the three were analyzed (Trial A: 728.1 ± 458.7; Trial B: 703.7 ± 387.2 ml min−1, p = 0.639). The ICC was 0.95 (p < 0.0001), the Cronbach's Alpha 0.97, and the CV 13.3 ± 14.6 %. The ΔLBFpeak and ΔLVCpeak were significantly correlated across all three trials (r = 0.97, p < 0.0001) and the two most similar trials (r = 0.95, p < 0.0001), as determined by Pearson product‐moment correlation. These findings suggest that single PLM assessment of vascular function is reproducible, with clinical utility. For research purposes, conducting single PLM in triplicate greatly enhances the ability to detect within‐subject differences.

Support or Funding Information

This work was supported by National Institutes of Health Grant P01 HL091830 (to R.S.R.) and Veterans Affairs Rehabilitation Research and Development Service Grants E1697‐R and E6910‐R (to R.S.R.).
Impact of Sodium Nitrate on Measures of Vascular Function and Biomarkers of Inflammation in Patients with Peripheral Artery Disease: A Preliminary Assessment
Authors: Norton Samuel L , Ueda Kenichi , Ganger Charles T , Treichler David P , Casey Darren P
Published: November 2023

Peripheral artery disease (PAD) is associated with attenuated limb blood flow, reduced nitric oxide (NO) bioavailability, as well as elevated levels of circulating inflammatory and adhesion biomarkers. NO is a critical regulator of vascular tone and possesses several anti‐inflammatory properties. Recent evidence suggests that inorganic nitrate can be reduced to bioavailable NO in blood and various tissues. Thus, the aim of this study was to test the hypothesis that long‐term dietary nitrate supplementation in patients with PAD would 1) improve peak vasodilator capacity in resistance arteries of the arm and leg and 2) decrease plasma markers of inflammation (IL‐6) and cell adhesion (ICAM, VCAM, MCP‐1). 19 older adults with PAD (73 ± 10 yr) were randomly assigned to either 8‐weeks of daily oral sodium nitrate (NaNO3; 1g) or placebo. Peak blood flow was assessed using venous occlusion plethysmography in the forearm and calf following 5 minutes of ischemia (reactive hyperemia). Peak vascular conductance (surrogate for vasodilation) was calculated as blood flow/mean arterial pressure. Plasma levels of inflammatory and cell adhesion molecules were determined utilizing commercially available enzyme‐linked immunosorbent assays (RnD Systems). Preliminary analysis (2 way repeated measures ANOVA) of 12 patients that received NaNO3 and 7 patients that received placebo revealed no significant group × time interactions for any of the outcome measures. However, examination of only the NaNO3 group demonstrated that peak calf blood flow (10.7 ± 1.7 vs. 12.8 ± 1.8 ml/dL of limb volume/min) and vascular conductance (10.1 ± 1.5 vs. 12.7 ± 1.8 ml/dL of limb volume/min/100mmHg) increased post treatment (P < 0.05). Peak blood flow (P = 0.44) and vascular conductance (P= 0.45) in the arm did not change following treatment with NaNO3. Plasma levels of IL‐6 decreased post treatment (3.98 ± 0.64 vs. 3.49 ± 0.56 pg/ml, P < 0.05), however, NaNO3 had no effect on any of the plasma adhesion molecules (P = 0.15 – 0.43). Our preliminary data suggest that oral NaNO3 may provide a therapeutic benefit to vasodilator capacity in the lower extremity (i.e. diseased limb) of patients with severe PAD. Moreover, NaNO3 may promote an anti‐inflammatory effect in this patient population.

Support or Funding Information

Funded by the American Heart Association 13GRNT16490002 (DPC). The Undergraduate Summer Research Fellowship program is supported by the American Physiological Society (SLN).
Mapping gender‐specific modifiers of doxorubicin cardiotoxicity in BN and SS rats
Authors: Flister Michael , Plasterer Cody , Paddock Samantha , Jacob Julia , Lemke Angela
Published: November 2023

As the efficacy of cancer treatment improves, patients are living longer and the management of life‐threating toxicities of many anticancer drugs is being pushed to the forefront. The most insidious toxicities are those affecting the heart (i.e., cardiotoxicity) and anthracyclines, such as doxorubicin (DOX), are among the most cardiotoxic drugs used to treat cancer. Most breast cancer patients receive DOX and many develop cardiotoxicity do to unknown underlying genetic risks, yet no models for mapping DOX cardiotoxicity in females exist. Here, we identified the first rodent model for mapping gender‐specific modifiers of DOX cardiotoxicity in females. Echocardiography was used to assess cardiotoxicity in SS and BN rats treated with DOX (2mg/kg for 8 weeks; n=5–7 rats per group). Compared with controls, male BN and SS rats both developed significantly reduced cardiac output following 8 weeks of DOX treatment, which did not differ between the strains. In comparison, fractional shortening (FS) in female SS rats decreased by 27±3% (P<0.001) following DOX treatment, whereas female BN rats had no changes in FS (2±3%). In total, we compared pathological changes in 59 physiological and cardiovascular traits in DOX‐treated female BN and SS rats, of which 8 (13%) and 21 (36%) changed significantly (P<0.05), respectively. These physiological measurements ranging from serum profiles to cardiac fibrosis, capillary density, and echocardiography, suggest that SS female rats are far more susceptible to DOX cardiotoxicity than BN female rats. Collectively, these data also suggest that the BN and SS rat strains can be used to map female‐specific genetic modifiers of DOX‐mediated cardiotoxicity for the first time.

Support or Funding Information

National Institutes of Health (1R01CA193343‐01)
Roles of sex‐specific regulation of vascular soluble epoxide hydrolase in flow‐induced vasodilator responses
Authors: qin jun , Kandhi Sharath , Froogh Ghezal , Jiang Houli , Sun Dong , Huang An
Published: November 2023

We hypothesized that potentiating the bioavailability of endothelial epoxyeicosatrienoic acids (EETs) via deletion of the gene for soluble epoxide hydrolase (sEH), or downregulation of sEH expression, enhances flow/shear stress‐induced dilator responses (FID) of arterioles. Using male (M) and female (F) wild type (WT) and sEH‐knockout (KO) mice, isolated gracilis muscle arterioles (90–150 μm in diameter) were cannulated and pressurized at 80 mmHg. Basal tone and increases in diameter of arterioles as a function of perfusate flow (5, 10, 15, 20 and 25 μl/min) were recorded. The magnitude of FID was significantly smaller (14.9 ± 0.8 %PD at maximal flow rate), and associated with a greater arteriolar tone (61.5 ± 1.1 %PD at 80 mmHg) in M‐WT than F‐WT mice (maximal flow rate: 22.3 ± 2.1 and basal tone: 74.4 1.6 %PD), revealing a sex‐difference in FID. This sex‐difference was abolished by deletion of the sEH gene, as evidenced by an enhanced FID in M‐KO mice to a level comparable to those observed in F‐KO and F‐WT mice. These three groups of mice coincidentally exhibited an increased endothelial sensitivity to shear stress expressed as smaller WSS50 (8.9±1.3 in M‐KO; 7.9±1.0 in F‐KO and 8.7±1.1 in F‐WT) compared to M‐WT (12.4 2.0) and were hypotensive. Endothelial EETs that did not contribute to FID in M‐WT mice, participated in the mediation of enhanced FID in M‐KO, F‐KO and F‐WT mice, as evidenced by inhibiting the enhancement with PPOH (an EET synthase inhibitor). Protein expression of sEH was downregulated by approximately 4‐fold in vessels of F‐WT compared to M‐WT mice, paralleled with greater vascular EET levels that were comparable to those observed in both male and female sEH‐KO mice. In conclusion, sex‐different expression of sHE accounts for sex differences in FID of microvessels in gonadally intact mice, characterized as a female‐specific downregulation of sEH that imitates the action of deleting sEH gene, leading to the enhancement of FID in F‐WT mice identical to those in sEH‐KO mice.

Support or Funding Information

This work was supported by NIH grant HL070653
Obesity‐Associated Impairments in Autonomic Control of Blood Pressure and Heart Rate are Sex‐Specific
Authors: Bruder‐Nascimento Thiago , Ekeledo Obioma J. , Anderson Ruchi , Le Huy B. , Belin de Chantemele Eric J.
Published: November 2023

Body weight gain induces cardiovascular disease by increasing sympathetic activity in males. Whether increasing body mass similarly affects autonomic control of cardiovascular function in males and females is unknown. Based on the evidence that sympathetic tone is lower in lean females than males, we tested the hypothesis that obesity‐associated impairments in autonomic control of blood pressure and heart rate are sex‐specific. Male and female C57Bl/6 mice were submitted to either a control (CD) or a high fat diet (HFD) for 24 weeks to induce obesity. Female mice gained more adipose mass and lost more lean mass compared to males. However, male and female mice reached a similar body weight (male: 51±8 vs. female: 48±8 g, NS.) at the end of the diet. HFD induced a similar and significant increase in plasma leptin, insulin, glucose, cytokines and lipids levels in male and female mice. Measurement of blood pressure (BP) and heart rate (HR) in conscious mice revealed that HFD did not elevate systolic, diastolic or mean arterial pressure (male CD: 122±6, HFD: 116±6 vs. female CD: 115±4 vs. HFD: 110±3 mmHg), but significantly increased HR in males (CD: 571±9, HFD: 631±14, P<0.05) and females (CD: 589±19 vs. HFD: 642±6, P<0.05). Indexes of autonomic control of BP and HR were obtained by measuring BP and HR response to ganglionic blocker, and to β‐adrenergic and muscarinic receptor antagonists. These experiments conducted in conscious animals revealed that HFD increased vascular sympathetic drive in male (CD: −43±4 and HFD: −60±7% drop in BP, P<0.05) but not female mice (CD: −37±4% and HFD: −40±4% drop in BP, NS). Consistent with the concept that increasing sympathetic tone reduces vascular adrenergic reactivity, HDF specifically reduced aortic α‐adrenergic constriction in male mice. Aortic α‐adrenergic reactivity remained intact in HFD females. In both sexes, aortic constrictions to serotonin or potassium chloride, and endothelium‐dependent and independent relaxations remained preserved. HFD reduced HR response to β‐adrenergic blockade in both sexes, suggestive of a reduction in cardiac sympathetic tone. HFD lowered HR response to muscarinic receptor blockade in females only, indicative of a reduced vagal tone. All together these data suggest that obesity‐associated increases in HR is likely caused by a decrease in vagal tone in female mice, while the increased in HR in males might be a mechanism to preserve BP and compensate for the reduced vascular adrenergic reactivity.
Hypertension and Type II diabetes are not associated with visceral inflammation or vascular remodeling/fibrosis in obese women
Authors: Fernandes Roxanne , Fink Gregory D , Galligan James J , Watts Stephanie W , Pereira‐Hicks Cristiane , Watson Ralph E , Lane Mindy , Xu Hui
Published: November 2023

Hypertension (HT) and Type 2 diabetes (T2D) are more common in overweight and obese subjects, but mechanistic links have not been fully established. Some evidence indicates that low level inflammation, especially in visceral fat depots, provides one such link in part by promoting vascular remodeling/fibrosis. Here we sought to determine if inflammation and splanchnic vascular remodeling/fibrosis were more prevalent in obese women with hypertension and/or T2D than obese only.

METHODS

We blindly evaluated H&E stained mesenteric vessels and perivascular adipose tissue obtained from 29 female patients who underwent Roux‐en‐Y bariatric surgery. Based on this evaluation, the patients were separated into two groups, according to the observed relatively prevalence and severity of histological alterations (vascular remodeling/fibrosis, angiogenesis, and inflammation). Tissues from 11 patients showed relatively mild histological changes (Group A), while tissues from the other 18 patients displayed more severe histological alterations (Group B). Based on their medical histories, the number of patients with HT, T2D, HT+T2D or neither condition (obese only: OO) were determined for both groups.

RESULTS

HT+T2D was slightly (but not significantly) higher in group B than group A (3/11, 27.7% vs 8/18, 44.4%). OO (3/11, 27.3% vs 5/18, 27.7%), HT (3/11, 27.3% vs 3/18, 16.6%), and T2D (3/11, 27.3% vs 2/18, 11.2%) were all similar in groups A and B. There were no differences in age (45 ± 3y vs 49 ± 2y), BMI (43.3 ± 3% vs 44.1 ± 2%) or occurrence of hyperlipidemia (6/11, 54.5% vs 9/18, 50%) between the two groups. To confirm our observations in H&E stained tissues, we randomly selected three patients from each category (OO, HT, T2D and HT+T2D), and evaluated vascular remodeling/fibrosis in Masson's trichrome stained tissues (for collagen) and macrophage infiltration into perivascular adipose tissue (CD 68 staining). The results showed no correlation between vascular remodeling/fibrosis, or adipose tissue inflammation, and HT or T2D.

CONCLUSIONS

Our studies do not support the hypothesis that inflammation and vascular remodeling/fibrosis in the splanchnic region cause hypertension or T2D in obese women.

Support or Funding Information

Supported by NIH 2P01HL070687 (For Drs Fink, Galligan, Watts and Xu)
Sex‐specific transcriptomic regulation in the diseased human heart
Authors: Kararigas Georgios , Summer Holger , Baczko Istvan , Golz Stefan , Regitz‐Zagrosek Vera
Published: November 2023

Pressure overload‐induced left ventricular (LV) hypertrophy and heart failure manifest differently between men and women. Transcriptional regulation is crucial in many (patho)physiological processes. We aimed at studying the impact of sex on global gene expression in LVs of men and women with aortic stenosis (AS) and end‐stage dilated cardiomyopathy (DCM) compared with LVs of men and women with no cardiovascular disorder (n = 5–10/group). Genome‐wide expression profiling was performed using the Affymetrix platform and the data were analyzed with R and Bioconductor considering adjusted P < 0.05 significant. In AS, fibrosis‐related genes were induced in male samples, while ribosomal and energy‐related genes were repressed. Female‐specific repressed genes in AS included extracellular matrix‐related and inflammatory genes, while members of the mitochondrial carrier protein family were induced. Similarly, pathway analysis revealed that fibrosis‐related pathways were induced in male AS samples, while inflammatory pathways were repressed in female AS samples. In DCM, male‐specific induced genes included several members of the immunoglobulin family, while a number of ribosomal and energy‐related genes were repressed. Female‐specific induced genes in DCM included those encoding several zinc finger proteins, while members of protein polyubiquitination were repressed. Pathway analysis revealed induction of ECM‐receptor interaction and inflammatory pathways in male DCM hearts, while the oxidative phosphorylation and proteasome pathways were repressed. In female DCM hearts, the Wnt and Hedgehog signaling pathways were induced, while the mTOR signaling pathway was repressed. The present findings offer an important insight into disease biology, a novel sex‐specific aspect of gene regulation in the human hypertrophied and failing heart, and may have a wide implication in the development of new and personalized therapies.

Support or Funding Information

DZHK (German Centre for Cardiovascular Research)
Multiparametric Determination of Renal Hemodynamics and Oxygenation using Non‐Invasive Magnetic Resonance Imaging in Healthy Volunteers
Authors: Eckerbom Per , Cox Eleanor , Subasic Irfan , Weis Jan , Palm Fredrik , Hansell Peter , Francis Susan , Liss Per
Published: November 2023

Purpose

Due to the risks associated with using contrast media in patients with impaired renal function there is clearly a need for non‐invasive techniques measuring renal blood flow (RBF) and oxygenation. Current techniques include arterial spin labelling (ASL), blood oxygen level‐dependent (BOLD) magnetic resonance imaging (MRI) and phase contrast (PC). In addition to needing thorough validation, it is also important to know if RBF and oxygenation are influenced by circadian rhythm. Therefore, we determined total and regional RBF and regional oxygenation in healthy volunteers as a function of time of day using these MRI.

Methods and Materials

Total RBF was determined by PC in renal arteries, regional RBF by ASL and regional oxygenation by BOLD in 6 healthy volunteers every fourth hour for a total of 24 hours resulting in 6 repeated measurements in each individual.

Results

Average total RBF was 898±10 ml/min and 893±27 ml/min for right and left kidney, respectively, with a drop during evening‐night but with significant individual variations. Average cortical RBF was 289±7 and 274±8 ml/min/100g for right and left kidney, respectively, with highest values during the day and lowest values during the evening‐night. Cortical oxygenation was 52±1 and 49±1 ms for right and left kidney, respectively, with minimal circadian variation.

Conclusion

Non‐invasive MRI is able to quantify also substile changes in RBF. Furthermore, these results demonstrate that RBF is influenced by circadian variations which should be considered when designing future studies in order to elucidate the role of deranged RBF regulation for the development of kidney disease.
Renal hemodynamics and tubular function are preserved when hydroxyethyl starch is dosed to acutely restore blood pressure after blood loss in rats
Authors: Fu Yiling , Qiu Hongyu , Kelada John , Khang Ser , Honndorf Stefanie , Vallon Volker
Published: November 2023

Hydroxyethyl starch (HES) is used clinically to replace blood loss and stabilize hemodynamics. However, the fate of HES in the kidney and the functional consequences on kidney function have not been fully investigated. The goal of this study was to determine whether a single application of hydroxyethyl starch, dosed to rapidly restore blood pressure (BP) following a blood loss, affects renal hemodynamics or transport when assessed one week later.

Methods

Under short‐term anesthesia, Sprague‐Dawley rats were subjected to a 25% blood loss over 6.25 min via the femoral vein. Immediately thereafter, Volulyte® 6% containing HES 130/0.4 (VOL) or Hextend® 6% containing HES 670/0.7 (HEX) or a balanced crystalloid solution (Isolyte®, ISO) were infused i.v. to restore BP within 4–4.5 minutes. Pilot studies established that this required doubling of the infused volume of ISO (20ml/kg) vs VOL and HEX (each 10ml/kg). Sham operated rats without blood loss/volume substitution were used as control (CON). One week later, renal function was determined in renal clearance studies (using 3H‐inulin and paramino hippurate [PAH]) under terminal anesthesia. N=10/group.

Results

Body weight, heart rate, and plasma concentrations of glucose, chloride, calcium, phosphate and hematocrit were similar among the 4 group (not shown). Mean arterial pressure (MAP), renal hemodynamics (including GFR and renal blood flow [RBF]), tubular reabsorption of fluid, chloride (Cl), glucose, calcium (Ca), and phosphate (P), and tubular secretion of PAH were likewise not different among the 4 groups (see table: MAP [mmHg]; GFR, RBF [ml/min]; FR‐Ex, fractional renal excretion [%]).

MAP
GFR
RBF
FR‐Ex
FR‐Ex
FR‐Ex
FR‐Ex
FR‐Ex
FR‐Ex

fluid
Cl
glucose
Ca
P
PAH

CON
121±5
2.5±0.1
19.3±2.0
1.0±0.1
0.3±0.1
0.1±0.1
0.9±0.2
2.3±1.1
391±39

ISO
121±5
2.4±0.1
18.4±2.0
0.9±0.1
0.4±0.1
0.1±0.1
0.9±0.1
3.8±1.5
392±43

VOL
118±3
2.5±0.2
19.2±3.1
0.9±0.1
0.3±0.1
0.1±0.1
0.9±0.1
2.5±1.0
410±72

HEX
126±3
2.3±0.2
19.3±3.5
1.1±0.2
0.5±0.2
0.1±0.1
1.0±0.2
3.3±1.4
422±54

Conclusion

A single bolus infusion of VOL or HEX, dosed to acutely restore BP after a 25% blood loss in rats, does not alter renal hemodynamics or tubular transport function compared with sham operation or volume substitution with ISO, when assessed one week later.

Support or Funding Information

National Institutes of Health O'Brien Center (P30DK079337), Fresenius Kabi Deutschland GmbH
Impaired Renal Autoregulation after Ischemia‐Reperfusion Results from Loss of Dynamic Stability Normally Conferred by Tubuloglomerular Feedback
Authors: Thomson Scott C , Pham Hai , Bourgette Ryan , Singh Prabhleen
Published: November 2023

Background

Autoregulation of renal blood flow (Q) results from combined actions of myogenic (Myo) and tubuloglomerular feedback (TGF) systems. Surprisingly little is known about intra‐renal hemodynamics or autoregulation after acute kidney injury.

Method

We subjected rats (n=13) to renal ischemia‐reperfusion (IR, bilateral pedicle clamp × 1h) or sham ischemia. After 4 or 24 hrs, rats were re‐anesthetized (inactin) and 2‐hr recordings made of spontaneous left renal blood flow (Q) and arterial pressure (BP) while measuring 2‐kidney inulin clearance (GFR). We examined the dynamic relationship between Q and BP by two methods: First, we generated admittance spectra from short‐term Fourier transforms. This is a proven method for detecting TGF and Myo systems, which give respective resonance peaks at 0.03 and 0.15 Hz. Second, we generated autoregulatory step responses by applying the projection theorem to approximate Q as a linear sum of past BP and expressed the result as the fractional compensation following an idealized unit step in BP. The step response out‐performs spectral methods for quantifying the efficiency of autoregulation.

Results

Data from 4 and 24h were similar and are pooled. GFR was depressed after IR (0.5± 0.3 vs 2.1±0.3 ml/min, P<0.002) but Q was not (14.8±1.9 vs 13.6±2.0 ml/min, P=0.7). Spectral analysis detected Myo activity in both Sham and IR but detected TGF activity only in Sham. Step responses diverged during the 10–20s window where TGF normally contributes most. For BP disturbances lasting longer than 15s, fractional compensation was less by ~50% in IR vs Sham.

Interpretation

Q is rapidly restored after IR, while GFR remains low enough that BP fluctuations cannot produce a TGF signal, which derives from flow in the tubule. Without a contribution from TGF, overall autoregulatory efficiency is diminished and Q is susceptible to changes in BP. This has implications for how to manage patients recovering from acute kidney injury.

Support or Funding Information

Veterans Administration Research Service and UCSD‐UAB O'Brien Center for Acute Kidney Injury (P30‐DK‐79337).