Endothelium-mediated Vasodilation Research Articles

Obesity-induced mesenteric PVAT remodelling is sexually dimorphic, but not driven by ovarian hormones

BackgroundObesity, a major risk factor for cardiovascular disease (CVD), is associated with hypertension and vascular dysfunction. Perivascular adipose tissue (PVAT), a metabolically active tissue surrounding blood vessels, plays a key role in regulating vascular tone. In obesity, PVAT becomes dysregulated which may contribute to vascular dysfunction; how sex impacts the remodelling of PVAT and thus the altered vascular contractility during obesity is unclear.ObjectiveTo investigate sex-specific PVAT dysregulation in the setting of obesity as a potential driver of sex differences in vascular pathologies and CVD risk.MethodsAdult male and female C57Bl/6J mice were fed an obesogenic high-fat diet (HFD) or regular chow for 16 weeks. Mesenteric PVAT (mPVAT) was isolated for RNA-sequencing and histological analysis, and mesenteric arteries were isolated for assessment of vascular function by wire myography. In a separate study, female mice were subjected to bilateral ovariectomy prior to dietary intervention to determine the contribution of ovarian hormones to PVAT dysregulation.ResultsTranscriptomic analysis of mPVAT revealed sexually dimorphic responses to HFD, with upregulation of extracellular matrix (ECM) remodelling pathways in male but not female mice. Histological and RT-qPCR approaches demonstrated increased collagen deposition and ECM remodelling in mPVAT from obese male compared with obese female mice. Assessment of vascular function in mesenteric arteries -/+ PVAT revealed that in obesity, mPVAT impaired endothelium-mediated vasodilation in male but not female mice. Ovariectomy of female mice prior to HFD administration did not alter ECM transcript expression or collagen deposition in mPVAT compared to sham-operated female mice.ConclusionsObesity induces sex-specific molecular remodelling in mPVAT, with male mice exhibiting unique upregulation of ECM pathways and increased collagen deposition compared to females. Moreover, the relative protection of female mice from obesity-induced mPVAT dysregulation is not mediated by ovarian hormones. These data highlight a potential sex-specific mechanistic link between mPVAT and mesenteric artery dysfunction in obesity, and provides crucial insights for future development of treatment strategies that consider the unique cardiovascular risks in men and women.Graphical abstract

Evaluation of differences in cardiovascular and metabolic effects of chronic caffeinated and decaffeinated coffee intake

Although coffee is one of the most popular beverages, the relationship between chronic consumption and cardiovascular health remains controversial. Therefore, this study investigated the effects of chronic consumption of caffeinated or decaffeinated coffee on biochemical profile and cardiovascular response. Three groups of rats were treated with HPLC characterized caffeinated or decaffeinated coffee and control for six weeks; blood pressure and biochemical profile were analyzed, followed by in vitro aortic ring experiments. The results showed that both coffees reduced blood glucose, AST and ALT. However, only caffeinated coffee elevated blood pressure in vivo, whereas aortic rings with endothelium increased the vasocontractile response; this effect was reversed by the addition of indomethacin and L-NAME also reduced the endothelium-mediated vasodilator response. In conclusion, chronic intake of any type of coffee positively improves biochemical profile. However, caffeinated coffee reduces nitric oxide biosynthesis and increases vasoconstrictor prostanoid production, whereas decaffeinated coffee preserves vascular function.

Endothelium-mediated vasodilation: associations with cardiometabolic diseases and their risk factors in aging

Aim. To evaluate the association of flow-mediated vasodilation (FMD) with cardiometabolic diseases (CMDs) and their risk factors (RF) in old age.Material and methods. The study was conducted in the Russian population cohort of the HAPIEE project (Novosibirsk, 2015-2018). Endothelial function was assessed in a random subsample (788 men and women aged 55-84 years) using ultrasound measurements of the brachial artery FMD. Endothelial dysfunction (ED) was recorded with FMD <10%. Cardiovascular diseases (CVD) and risk factors were assessed using standard epidemiological methods.Results. The incidence of hypertension (HTN) was 78,8% (the same in men and women), major CVDs — 21,7% and 17,1%, type 2 diabetes (T2D) — 18,7% and 19,1% in men and women, respectively. The mean FMD values were 2,7% (SD 7,32) and 3,2% (7,19), while the prevalence of ED was 88,2% and 85,8% in men and women, respectively, and did not differ significantly by sex. Men with ED had higher levels of blood triglycerides (125,1 (71,23) vs 102,7 (45,79) mg/dl; p=0,033), waist/hip circumference indices (0,94 (0,050) vs 0,92 (0,076); p=0,009) and body weight (27,7 (45,79) vs 26,5 (4,36) kg/m2; p=0,077). In women, a tendency towards an association of ED with smoking was revealed (p=0,067). There were no associations of ED with HTN, T2D and CVD in men and women.Conclusion. The PMD test demonstrated a high incidence of ED in a population sample of 55-84 years old. ED is associated with metabolic risk factors in men and smoking in women. No associations of PMD with CMDs were found, presumably due to the high incidence of ED and cumulative disease in the elderly. Modification of metabolic risk factors and smoking cessation are relevant at any age to prevent the progression of ED.

The effects of metabolic syndrome on arterial stiffness: A concise review.

Madam, The term "metabolic syndrome" describes a collection of diseases that escalates a person’s risk of cardiovascular disease, stroke, adult-onset diabetes, and other severe health issues. It is also known as Insulin resistance syndrome. A major cause of metabolic syndrome is the development of resistance to insulin due to high levels of fats. (1) Multiple risk factors, including abdominal and central obesity, increased blood pressure, low amount of HDL, and higher amount of LDL and triacylglycerides characterize it. Metabolic syndrome and arterial stiffness are interconnected conditions that can significantly impact cardiovascular health. (2) Arterial stiffness is a condition that considers the rigidity of the arterial wall. It involves modification of the automated aspects of the walls of arteries. The macroscopic geometry as well as the intrinsic characteristics of the artery, play a role in its stiffness. (3) Several mechanisms lead to arterial stiffness in metabolic syndrome patients, the first being inflammation. Upon excess nutrition, adipocytes increase in size and number, which causes decreased perfusion, causing hypoxia. Cell necrosis with the invasion of macrophages and the synthesis of adipocytokines, which consist of the pro-inflammatory mediators, might result from this condition. (1) The increased vascular inflammation will promote vascular fibrosis, smooth muscle cell proliferation, and endothelial-mediated vasodilation, which will ultimately increase arterial stiffness. (4) Metabolic syndrome is also related to insulin resistance, lipidemia, and central obesity. Chronic hyperglycemia and hyperinsulinemia may enhance sympathetic nervous system activity, vascular inflammation, and renin-angiotensin system activity. Vascular tissue's angiotensin-aldosterone system results in fibrosis and wall enlargement. Middle-aged people transitioning from gaining body weight to established conditions like hypertension and type 2 diabetes experience arterial stiffness. This transition typically starts with a few minor changes, but Metabolic Syndrome develops when several risk factors are present. (5) In conclusion, there is evidence to suggest arterial stiffness and metabolic syndrome are closely related and have significant implications for the well-being of an individual. It is essential to address both conditions as they may lead to atherosclerosis, followed by more frequent cardiovascular events and higher mortality. There are various strategies to counter the rise of arterial stiffness, like adding exercises to routines and vitamin K-rich foods to the diet, which will in turn reduce the occurrence of metabolic syndrome disorders in individuals, thus leading to a healthier society.

Endothelial dysfunction is associated with reduced myocardial mechano-energetic efficiency in drug-naïve hypertensive individuals.

Impaired myocardial mechano-energetics efficiency (MEE) was shown to predict incident heart failure, but pathophysiological mechanisms linking impaired MEE with heart failure have not been elucidated. Endothelial dysfunction is a plausible candidate because it has been associated with heart failure. This study aims to investigate the association between MEE and endothelium-dependent vasodilation, among drug-naïve hypertensive individuals. 198 Drug-naïve hypertensive individuals participating in the CATAnzaro MEtabolic RIsk factors (CATAMERI) study were included. All participants underwent to an oral glucose tolerance test and to an echocardiogram for myocardial LVM-normalized mechano-energetic efficiency (MEEi) measurement. Endothelial-dependent and endothelial-independent vasodilatation were measured by strain-gauge plethysmography during intra-arterial infusion of acetylcholine and sodium nitroprusside, respectively. A multivariate linear regression analysis was conducted to investigate the independent association between maximal endothelial-dependent vasodilation and MEEi. Maximal ACh-stimulated forearm blood flow (FBF) was associated to decreased myocardial MEEi (β = 0.205, p = 0.002) independently of well-established cardiovascular risk factors including age, sex, BMI, waist circumference, smoking status, total and HDL cholesterol, triglycerides, hsCRP, glucose tolerance status, and HOMA-IR index of insulin resistance. Conversely, no association was observed between SNP-stimulated vasodilation and MEEi. Endothelium-mediated vasodilation may contribute to reduce myocardial MEEi independently of several potential confounders. Because diminished myocardial MEE has been previously associated with incident heart failure, a non-invasive assessment of myocardial MEEi may improve the identification of individuals at higher cardiovascular risk who may benefit from the initiation of pharmacological treatments ameliorating the endothelial dysfunction.

Nitric oxide contribution to endothelium-mediated vasodilation is attenuated in postmenopausal compared to premenopausal females

Background: Hypertension prevalence increases in females following menopause. Poor endothelial microvascular function increases risk of hypertension. Endothelial-mediated vasodilation is dependent on nitric oxide (NO). Estrogen enhances NO production; therefore, reduced estrogen levels in postmenopausal females may result in a reduced contribution of NO to endothelial-mediated vasodilation, although studies are limited. Herein, we aimed to investigate the contribution of NO to endothelial-mediated vasodilation in premenopausal and postmenopausal females. We hypothesized that postmenopausal females would have attenuated endothelium-mediated vasodilation and reduced contribution of NO compared to premenopausal females. Methods: Ten premenopausal (27±3 yrs) and eleven postmenopausal (59±4 yrs) normotensive females were studied. Resting brachial blood pressures were measured using a standard arm cuff. Brachial arterial catheters were placed for continuous blood pressure measurement and pharmacologic infusions. Forearm blood flow (FBF) was measured using venous occlusion plethysmography at baseline (saline) and during infusion of an endothelium-dependent vasodilator (acetylcholine; 1.0, 2.0, 4.0, and 8.0 μg/100mL tissue/min) with and without a NO synthase inhibitor (L-NG-monomethylarginine [L-NMMA]; 1.0 mg/min) co-infusion. Forearm vascular conductance (FVC) was calculated as FBF/mean arterial pressure✕100. Data were analyzed using a two-way repeated-measures ANOVA. Results: Resting systolic blood pressure (SBP) but not diastolic blood pressure (DBP) was greater in postmenopausal compared to premenopausal females (SBP: 121±15 vs. 103±9 mmHg, respectively; P<0.01; DBP: 72±11 vs. 65±5 mmHg, respectively; P=0.07). FBF responses to acetylcholine did not differ between premenopausal and postmenopausal females (Group Main Effect: P=0.11). When correcting for blood pressure, premenopausal females exhibited greater FVC responses to acetylcholine compared to postmenopausal females (Group Main Effect: P=0.04). In premenopausal females, FBF and FVC responses to acetylcholine were reduced with co-infusion of L-NMMA compared to acetylcholine infusion only (L-NMMA Main Effect: P=0.02 and P=0.01, respectively). In postmenopausal females, the FBF and FVC responses to acetylcholine were unaffected by L-NMMA (L-NMMA Main Effect: P=0.79 and P=0.76, respectively). Conclusion: Compared to premenopausal females, postmenopausal females have impaired endothelial microvascular function. Attenuated NO contribution during endothelium-mediated vasodilation in postmenopausal women may partially contribute to the increased hypertension risk in this population. AHA 14PRE18040000, AHA 898649, NIH HL083947, NIH HL148144, NCATS UL1 TR000135 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Circulating factors following doxorubicin treatment in a tumor-bearing model induce endothelial dysfunction

Chemotherapy (CTx) is essential to prevent the growth of tumors and has increased patient survival significantly. However, CTx agents have cardiotoxic side effects that can ultimately lead to heart failure. As a result, cardiovascular (CV) death is now the second leading cause of death in cancer patients. It has been accepted that adverse CV events are driven by a dysfunctional microcirculation, therefore CTx-induced endothelial dysfunction may play a key role in development of myocardial pathologies.Many CTx agents induce mitochondrial DNA (mtDNA) damage as many drugs intercalate into double stranded DNA, promoting the release of cell-free mtDNA (cf-mtDNA) into the circulation. Toll-like receptor 9 (TLR9) on the vascular endothelium detects cf-mtDNA and results in an inflammatory response. Prolonged exposure to CTx agents may enhance the mtDNA damage and stimulate the release of additional cf-mtDNA. To determine whether increased drug exposure exacerbates mtDNA damage, two forms of clinically used CTx were utilized: doxorubicin (Dox) and a lysosomal-derived nanoparticle with encapsulated Dox (Dox-NP), which targets tumor cells more specifically. With the ability of tumor-targeted delivery via Dox-NP, we hypothesize that Dox-NP augments mtDNA damage and the inflammatory response.Male Sprague Dawley rats received rat hepatoma-derived tumor cells into the liver twelve days prior to treatment start. Rats were treated with one weekly Dox or Dox-NP injection (7.5mg/kg·BW) for two weeks (cumulative dose 15mg/kg·BW). Cardiac function was evaluated before and six weeks after the initial dose of CTx. Vessel function was evaluated following euthaniasia six weeks after the initial dose. Plasma was obtained upon euthanasia, and cf-mtDNA levels were quantified via qPCR. NF-kB expression, downstream of TLR9 was determined via western blot.Rat microvessels from both treatment groups showed reduced endothelial-mediated vasodilation. Quantification of cf-mtDNA showed a trend toward increased cf-mtDNA levels in response to both Dox and Dox-NP. Likewise, NF-kB expression was elevated three-fold in comparison to Dox. To confirm whether endothelial dysfunction was the result of the inflammatory TLR9 signaling in vivo, isolated human microvessels were treated with 100nM Dox-NP. Vasodilation was not impaired, suggesting that Dox-NP is not directly harmful to the endothelium.Together, these data indicate that tumor-targeted Dox-NP have little to non-direct impact on the endothelium. Thus, endothelial dysfunction in animals treated with Dox-NP is secondary to its effects on a tumor and may be mediated by tumor-derived cf-mtDNA and TLR9 signaling. Moreover, the present data shows that direct effects of standard Dox on ECs may be only partially responsible for impaired dilator function. Conclusively, this work supports the concepts of a new mechanism of Dox-induced endothelial dysfunction. This work was supported by the NIH, 5 R01 HL133029-0 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Systemic microvascular response to insulin is associated with risk of heart failure with preserved ejection fraction in women with type 2 diabetes

Abstract Background Endothelial microvascular dysfunction (MD) is a key pathophysiologic mechanism for heart failure with preserved ejection fraction (HFpEF). Comorbidities such as type 2 diabetes (T2D) indeed can affect the endothelium of both peripheral and coronary microcirculation, thereby triggering systemic derangements as well as left ventricular diastolic dysfunction (LVDD). Altered microvascular response to insulin is common in T2D but its clinical relevance and association with cardiovascular risk and particularly HFpEF remains unclear. Likewise, the involvement of systemic MD in early HFpEF and LVDD is uncertain. Finally, the influence of sex on MD and on its association with HFpEF needs further investigation to help understand the female predominance in HFpEF. Purpose We aimed to characterize systemic MD in T2D, and investigate its association with clinical and echocardiographic markers of LVDD/HFpEF. Further, we aimed to test for effect modification by sex in the association between MD and LVDD/HFpEF. Methods 152 prospectively enrolled participants (77 men, 75 women) from the Hoorn Diabetes Care System Cohort underwent in vivo evaluation of MD, echocardiography and blood sampling. MD was assessed by laser speckle contrast analysis combined with iontophoresis of insulin (Ins), acetylcholine (ACh) and sodium nitroprusside (SNP). The association between indices of MD and markers of LVDD/HFpEF was assessed by multivariable linear regression analysis adjusted for confounders. LVDD was defined as presence of cardiac structural and functional abnormalities, according to current recommendation. Probability of HFpEF was estimated with the H2PEFF score. Results Mean age was 65±6y, mean HbA1c 7.5±1.2%, 70.6% were asymptomatic. Comorbidity burden and biomarkers did not significantly differ between the sexes. Women had smaller LV mass index (82.8±18.1 vs 99.2±20.3 g/m2) and higher E/E' (13.4±4.4 vs 11.3±2.8) compared to men. Skin perfusion plateau after application of each substance was higher in women than men but no significant differences between sexes were observed in terms of relative perfusion change, calculated as 100% × ([Perfusion plateau − Baseline flow] / Baseline flow) for any of the substances. The relative perfusion change due to Ins was associated with the H2PEFF score, independently of cardiovascular risk factors and cardiovascular drug use (1% increase in perfusion associated to 0.07% decrease of the H2PEFF score). Stratified by sex, this association was present only in women (1% increase in perfusion associated to 0.10% decrease of the H2PEFF score). No significant associations were observed between perfusion change after ACh and SNP and H2PEFF score or between any MD indices and LVDD markers. Conclusions Impaired endothelial-mediated vasodilation in response to insulin confers a higher risk of HFpEF in women with T2D. In vivo measures of systemic MD could represent novel cardiovascular risk markers, for refined risk prediction of HFpEF. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Young Investigator award grant, Early HFpEF and ShePredicts programs, Hartstichting, The Netherlands.

Paraoxonase 1 hydrolysis of EPA-derived lactone impairs endothelial-mediated vasodilation

Human serum paraoxonase-1 (PON1) is a lactonase that plays a significant role in anti-atherosclerotic high-density lipoprotein (HDL) activity. PON1 is also localized in endothelial cell membranes, where it is enzymatically active and regulates endothelial signals. PON1 has a high specificity for lipophilic lactones and has been shown to hydrolyze and regulate lactone lipid mediators derived from arachidonic polyunsaturated fatty acids (PUFA). Previously, we showed that an arachidonic acid lactone metabolite (AA-L) dose-dependently dilates PON1 gene deletion (PON1KO) mouse mesenteric arteries significantly more than wild-type arteries. In contrast, preincubation with HDL or rePON1 reduced AA-L-dependent vasodilation. Recently we showed that an additional δ-lactone metabolite derived from the eicosapentaenoic acid lactone, 5,6-δ-DiHETE lactone (EPA-L) reduced blood pressure by dilating microvessels of hypertensive rats. However, whether PON1 regulates the activity of the EPA-L lipid mediator is unknown. AimTo demonstrate that PON1 hydrolyzes EPA-L and to reveal the effect of this hydrolysis on endothelial-dependent vascular dilation. Methods and results:In vascular reactivity experiments, EPA-L dose-dependently dilated PON1KO mouse mesenteric arteries significantly more than wild-type mesenteric arteries. This dilation was not affected by nitric oxide inhibition. PON1 impaired the cellular calcium increase mediated by EPA-L in endothelial cells, though this impairment decreased with PON1 internalization to the cell. ConclusionThese findings support that PUFA-lactones are physiological substrates of PON1, and that PON1 activity in the endothelial membrane affects the dilation of microvessels that is induced by these endothelial-derived hyperpolarizing PUFA-lactones.

Prenatal Hypoxia is Associated with Coronary Artery Endothelial Dysfunction in Male and Female Offspring

IntroductionFetal hypoxia is a common consequence of complicated pregnancies and is linked to the development of cardiovascular (CV) dysfunction in the offspring. We showed an impaired cardiac function in adult prenatal hypoxia offspring, however, the mechanisms are not known. Coronary artery endothelial dysfunction has been shown to contribute to the development of cardiac dysfunction, however, whether endothelial function is impaired in coronary arteries of prenatal hypoxia offspring is unknown. We hypothesize that prenatal hypoxia leads to impaired coronary artery endothelial function in adult male and female offspring.MethodsPregnant Sprague‐Dawley rats were exposed to normoxia (21% O2) or hypoxia (11% O2; p‐Hyp) on gestational days 15‐21 (term=22 days). Male and female offspring were aged to 9‐9.5 months. Left anterior descending coronary arteries were isolated (n=5‐7/group), and endothelium‐dependent vasodilation to methylcholine (MCh) and endothelium‐independent vasodilation to the nitric oxide (NO) donor sodium nitroprusside (SNP) were assessed by wire myography. To assess the contribution of endothelial vasodilation pathways, MCh‐curves were performed in the presence/absence of inhibitors of nitric oxide synthase (L‐NAME), prostaglandin H synthase ([PGHS]; meclofenamate), or small‐ and intermediate‐conductance Ca2+‐activated potassium channels (apamin and TRAM‐34, respectively). Data were summarized as Emax (maximum vasodilation response), pEC50 (concentration required to produce 50% of Emax) or Area Under the Curve (AUC). Data were compared by two‐way ANOVA (Sidak's post hoc test); p<0.05 was significant.ResultsMch‐induced vasodilation (Emax) was decreased in p‐Hyp males (p=0.006) and females (p=0.032) compared to normoxia offspring. L‐NAME completely inhibited vasodilation (AUC) in normoxia and p‐Hyp males (p<0.0001). In the female offspring, incubation with L‐NAME completely inhibited vasodilation in the normoxia group (p<0.0001), but to a lesser extent (Emax ~15%) in the p‐Hyp offspring (p<0.0001). In contrast, meclofenamate did not alter MCh‐induced vasodilation (AUC) in males, while in females, meclofenamate increased vasodilation to MCh in the p‐Hyp group only (p=0.04). Apamin and TRAM‐34 did not alter responses to MCh in any of the groups. SNP sensitivity (pEC50) was decreased in p‐Hyp females compared to normoxia controls (p=0.012), without changes in males.ConclusionsOur data suggest that prenatal hypoxia leads to coronary artery endothelial dysfunction in male and female offspring. In prenatal hypoxia males, NO contribution to endothelium‐mediated vasodilation was reduced. In females, prenatal hypoxia increased PGHS‐dependent vasoconstriction and decreased smooth muscle sensitivity to NO. Understanding the mechanistic pathways involved in programming of CV disease may allow for the development of future prenatal and postnatal therapeutic interventions.

Evaluation of the presence of TRPC6 channels in human vessels: A pilot study using immunohistochemistry.

The TRPC6 channel is permeable to calcium ions as well as other ions and plays an important role in the physiology and pathophysiology of vessels. Findings from animal and cell culture experiments have shown its involvement in important vascular processes such as the Bayliss effect or endothelial-mediated vasodilatation. Furthermore, the relevance of TRPC6 channels in humans has become apparent based on diseases such as idiopathic pulmonary arterial hypertension, focal segmental glomerulosclerosis and atherosclerosis, amongst others. However, histological evidence that systematically detects TRPC6 channels in human vessels has not been provided to date. In this study, 40 vessel sections from nine body donors were obtained, processed and stained with a knockout-validated antibody against the TRPC6 protein using immunohistochemistry and western blotting. More than half of the samples yielded evidence of TRPC6 channel expression in the intima and adventitia. TRPC6 channels were detected in the tunica media in only one of 40 cases. TRPC6 detection in the human intima confirmed several demonstrated physiological aspects of the TRPC6 channels in the vasculature and may also be involved in associated human diseases. The near absence of TRPC6 channels in the tunica media was in contrast to a view that is primarily based on animal studies, from which its presence was assumed.

Effect of Combined Grape Seed Extract and L-Citrulline Supplementation on Hemodynamic Responses to Exercise in Young Males

Grape seed extract (GSE) or L-citrulline supplement has been known to increase nitric oxide (NO) bioavailability and enhance endothelial-mediated vasodilation. Accordingly, to examine the additive benefits of combination of the two supplementations on hemodynamic responses to dynamic exercise, young, healthy males were recruited for this study. Effects of 7 days of 1) GSE + L-citrulline, 2) GSE, 3) L-citrulline, and 4) placebo supplementation on systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), cardiac output, total vascular conductance (TVC), and oxygen (O2) consumption were examined at rest and during cycling exercise. Compared with placebo, GSE, L-citrulline, and combined supplementations did not reduce SBP, DBP, and MAP, while cardiac output (placebo; 23.6 ± 1.3 L/min, GSE; 25.7 ± 1.1 L/min; L-citrulline, 25.2 ± 1.2 L/min; GSE + L-citrulline; 25.3 ± 0.9 L/min) and TVC (placebo; 234.7 ± 11.3 ml/min/mmHg, GSE; 258.3 ± 10.6 ml/min/mmHg; L-citrulline, 255.2 ± 10.6 ml/min/mmHg; GSE + L-citrulline; 260.4 ± 8.9 ml/min/mmHg) were increased at only the 80% workload (p < 0.05). Compared with placebo and L-citrulline, GSE and combined supplementations had a reduction in VO2 across workloads (p < 0.05). However, there was no additive benefits on these variables. We conclude that supplementation with GSE, L-citrulline, and combined supplementations increased cardiac output due partially to decreased vascular resistance. Our findings suggest that GSE may act as an ergogenic aid that can improve O2 delivery to exercising muscles.

Dysfunction of Cullin 3 RING E3 ubiquitin ligase causes vasoconstriction and increased sodium reabsorption in diabetes

Impaired endothelium-mediated vasodilation and/or increased sensitivity to vasoconstrictors lead to vascular smooth muscle cell (VSMC) dysfunction in individuals with diabetes. Diabetic nephropathy is associated with a considerably higher risk of cardiovascular disease and death than their nondiabetic counterparts. We studied the activity of Cullin 3 RING ubiquitin ligase (CRL3) and its substrates in mice using an intraperitoneal injection of streptozotocin (STZ) and db/db mice. The levels of CRL3 adaptors, including Kelch-like 2/3 (KLHL2/3) and Rho-related BTB domain-containing protein 1, were significantly decreased in the aortic tissues and heart of the STZ group, whereas the levels of Cullin 3 (CUL3) and its neddylated derivatives were substantially increased. Decreased KLHL3 expression and significantly increased expression of NEDD8 conjugates were observed in the kidneys of db/db mice. The neddylation inhibitor MLN4924 decreased the degradation of KLHL2/KLHL3 under high-glucose conditions with/without insulin, and transfection with KLHL2 promoted the degradation of its substrates with-no-lysine (WNK) kinases. Increased abundance of WNK3, RhoA/ROCK activity and phosphodiesterase 5 enhanced the sensibility to vasoconstrictors and impaired vasodilation. Moreover, WNK3 localized in VSMCs undergoing cell division, and high-glucose medium increased WNK3 signaling in VSMCs undergoing mitosis, which might explain the increased thickness of aortic tissues in subjects with diabetes. Increases in WNK4 abundance resulted in increased sodium reabsorption in the distal renal tubules. Thus, KLHL2/RhoBTB1/KLHL3 inactivation in the aortic tissues and kidney is a result of excessive activation of neddylation in hyperglycemia and hyperinsulinemia, which affects vascular tone and sodium reabsorption.

Mineralocorticoid and Estrogen Receptors in Endothelial Cells Coordinately Regulate Microvascular Function in Obese Female Mice.

[Figure: see text].

Reversal of Arterial Stiffness by Rho‐related BTB Domain‐containing Protein 1 (RhoBTB1)

Rho-related BTB domain-containing protein (RhoBTB1) is a novel transcriptional target of peroxisome proliferator activated receptor Gamma (PPARg). The physiological and molecular function of RhoBTB1 is poorly understood. Human individuals carrying PPARg dominant negative mutation P467L develop early onset hypertension. Mice expressing smooth muscle-specific P467L also develop hypertension, vascular dysfunction, and arterial stiffness. Interestingly, P467L-mediated hypertension and its sequelae can be reversed by restoration of RhoBTB1 in smooth muscle, suggesting that RhoBTB1 mediates the anti-hypertension effect of PPARg in vascular smooth muscle cells. We recently found that RhoBTB1 preserves the nitric oxide-cGMP pathway by serving as a substrate adaptor for Cullin-3 and promoting phosphodiesterase 5 ubiquitination. Our current study explores the role of RhoBTB1 in angiotensin II (Ang-II) induced hypertension, a model that represents a broader hypertension population. We hypothesize that RhoBTB1 transgene expression in vascular smooth muscle will attenuate Ang-II-mediated hypertension and its sequelae. Mice expressing smooth muscle-specific, Tamoxifen inducible RhoBTB1 transgene (S-RhoBTB1) were used as experimental animals, whereas mice expressing smooth muscle-specific, Tamoxifen inducible Cre-recombinase (ISM-Cre) were used as control. Mice received 6-weeks of Ang-II infusion via osmotic mini pump at 490ng/kg/min. Transgene was induced by five daily Tamoxifen injections two weeks after Ang-II pumps implantation, allowing hypertension to be established before transgene activation. Blood pressure was monitored by radiotelemetry. Systolic, diastolic, and mean arterial blood pressure was significantly increased in response to Ang-II. RhoBTB1 transgene expression was not sufficient to reverse the high blood pressure. We also tested vascular reactivity in conduit and resistant arteries using wire myography. Ang-II infusion significantly impaired the vasodilation response to acetylcholine in carotid and mesenteric arteries, suggesting a defect in endothelium-mediated vasodilation. Like blood pressure, RhoBTB1 transgene expression was not sufficient to reverse the vasodilation impairment. Finally, we measured arterial stiffness using pulse-wave velocity (PWV). Both ISM-Cre and S-RhoBTB1 mice showed increased arterial stiffness two weeks after Ang-II infusion, indicated by a higher PWV. PWV in S-RhoBTB1 mice started to decline one-week post Tamoxifen and became significantly lowered (nearly reversed) two weeks after Tamoxifen. In comparison, PWV in ISM-Cre mice remained high till the end of the 6-weeks protocol. To explore the underlying mechanism, we evaluated the aortic compliance using pressure myograph in the absence of vascular tone and reactivity. Both pressure-diameter and stress-strain relationship indicate that RhoBTB1 transgene expression in smooth muscle improved the compliance of aorta in the presence of Ang-II, suggesting RhoBTB1 might attenuate arterial stiffness by acting on the extracellular matrix. Our study revealed a novel protective effect of RhoBTB1: attenuating established Ang-II-induced arterial stiffness.

Aging results in endothelial cell telomere uncapping that induces senescence, arterial stiffening, and reduced nitric oxide bioavailability

Advancing age results in arterial dysfunction that contributes to the development of cardiovascular disease. One plausible cause of arterial dysfunction in advanced age is elevated inflammation and oxidative stress derived from senescent cells, as senescent cells accumulate with age and display a pro-inflammatory, pro-oxidative phenotype. Telomeres are repeat DNA sequences that cap chromosome ends, shorten with each cell division, and are highly susceptible to oxidative damage. Importantly, when critically short or damaged, telomeres become uncapped, leading to cellular senescence. Here, we test the hypothesis that endothelial cell (EC) telomere uncapping occurs with advancing age, resulting in senescence-induced arterial dysfunction. To evaluate telomere uncapping, we examined colocalization of a DNA damage marker, 53BP1, and telomeres, using immunofluorescence-in situ hybridization in human lung ECs (HLECs). Indeed, HLECs from older donors (67±1 yr, N=2, 78 cells analyzed) had ~4.5 fold more cells containing ≥1 uncapped compared to HLECs from young sex matched donors (29±1 yr, N=2, 64 cells analyzed, p<0.01, Fig. 1). To investigate if EC telomere uncapping drives senescence and arterial dysfunction, we generated an EC-specific knockout mouse model of TRF2 (EC TRF2 KO), a telomeric binding protein that mediates telomere capping. We compared young (3.3 ± 0.2 mo) EC TRF2 KO mice to wild type, littermate controls (WT). Mouse lung ECs (MLECs) isolated from EC TRF2 KO mice had ~3 fold less TRF2 mRNA expression (N=6-7, p<0.001) compared to WT controls, resulting in increased telomere uncapping (N=5, p<0.001) and senescence, as demonstrated by a ~4.3 fold increase in the percentage of senescence associated β-galactosidase positive cells (N=3, p<0.01) and ~3 fold higher mRNA expression of the senescence marker, p21, in carotid artery ECs (N=3-8, p<0.001). Next, we assessed pulse wave velocity (PWV), a measure of large artery stiffness. PWV was increased by ~27% in EC TRF2 KO mice vs. WT controls (N=6-13, p<0.001, Fig. 2). Finally, we assessed endothelium-dependent dilation (EDD) to insulin in mesenteric arterioles and found that EC TRF2 KO mice displayed a ~62% reduction in EDD to insulin compared to WT controls (N=12-14, p<0.001, Fig. 3). This was nitric oxide (NO)-dependent, as there were no differences in insulin EDD when eNOS was inhibited with LNAME (N=12, p>0.05, Fig. 3). Endothelium-independent dilation to sodium nitroprusside was not different between EC TRF2 KO and WT mice (N=12-16, p>0.05). In summary, advancing age results in EC telomere uncapping in humans. In mice, genetically induced telomere uncapping in ECs results in senescence, increases arterial stiffness and attenuates endothelial-mediated vasodilation via reduced NO bioavailability.

A New Grape Seed Extract Pharma Standard Supplement (ECOVITISTM) Prevents and Controls Borderline Hypertension and Endothelial Dysfunction

This registry evaluates the effect of ECOVITIS™ (grape seeds extract) in borderline hypertension (also evaluating endothelialmediated vasodilatation). The main targets of the registry were the normalization of blood pressure and of an altered endothelial function (EF); 3 groups of 15 subjects used: Standard Management (SM) (GROUP 1); GROUP 2: SM+ECOVITIS™ (150 mg/day); GROUP 3: SM+ECOVITIS™ (300 mg/day). Results. The groups were comparable. Tolerability/safety were optimal. Blood tests, urines and ECG were normal at 4 and 12 weeks. BMI showed, minimal variations (&lt;26) in 3 months. Blood pressure (systolic, diastolic) and heart rate indicate a progressive improvement in Group 3 (p&lt;0.05) with better values at 4 and 12 weeks. The lower dose improved (p&lt;0.05) blood pressure and heart rate better than SM. Lipids and oxidative stress were improved better with the high dose (p&lt;0.05). The lower dose resulted better than SM (&lt;0.05). Other metabolic parameters (blood sugar and glycosylated hemoglobin) followed the same patterns (Group 3 resulted better that the other two groups) (p&lt;0.05). Laser Doppler measurements (skin flux) and strain gauge plethysmography measured an improvement in post-occlusive flow (EF) at the level of the arm (p&lt;0.65). This was confirmed by artery ultrasound measurements showing a larger increase in size in the brachial artery after occlusion with ECOVITIS TM (subjects in Group 3 had the best results (p&lt;0.025); the lower dose (Group 2) was superior to SM (p&lt;0.05). Tc PO2 increased more in group 3 (p&lt;0.05); PCO2 was decreased. Results in the lower dose group were better (p&lt;0.05) than results in the SM patients. In conclusion, this pilot registry shows that ECOVITIS™ is safe, well tolerated and may control and improve blood pressure and EF in borderline subjects. More studies may be needed for a longer period of time.

Undercarboxylated osteocalcin is associated with vascular function in female older adults but does not influence vascular function in male rabbit carotid artery ex vivo.

BackgroundThere are conflicting reports on the association of undercarboxylated osteocalcin (ucOC) in cardiovascular disease development, including endothelial function and hypertension. We tested whether ucOC is related to blood pressure and endothelial function in older adults, and if ucOC directly affects endothelial-mediated vasodilation in the carotid artery of rabbits.MethodsIn older adults, ucOC, blood pressure, pulse wave velocity (PWV) and brachial artery flow-mediated dilation (BAFMD) were measured (n = 38, 26 post-menopausal women and 12 men, mean age 73 ± 0.96). The vasoactivity of the carotid artery was assessed in male New Zealand White rabbits following a four-week normal or atherogenic diet using perfusion myography. An ucOC dose response curve (0.3–45 ng/ml) was generated following incubation of the arteries for 2-hours in either normal or high glucose conditions.ResultsucOC levels were higher in normotensive older adults compared to those with stage 2 hypertension (p < 0.05), particularly in women (p < 0.01). In all participants, higher ucOC was associated with lower PWV (p < 0.05), but not BAFMD (p > 0.05). In rabbits, ucOC at any dose did not alter vasoactivity of the carotid artery, either following a normal or an atherogenic diet (p > 0.05).ConclusionIncreased ucOC is associated with lower blood pressure and increased arterial stiffness, particularly in post-menopausal women. However, ucOC administration has no direct short-term effect on endothelial function in rabbit arteries. Future studies should explore whether treatment with ucOC, in vivo, has direct or indirect effects on blood vessel function.

Assessment of Cerebral Vasomotor Reactivity in Patients With Primary Open-angle Glaucoma and Ocular Hypertension Using the Breath-Holding Index.

Patients with ocular hypertension (OHT) do not show impaired cerebral vasodilation responses to hypercapnia but patients with primary open-angle glaucoma (POAG) do. Impaired vasoreactivity in patients with POAG may have neuronal or vascular origins and increase stroke risk. To investigate changes in cerebral blood flow and cerebral vasomotor reactivity using the breath-holding index in patients with POAG and OHT, to examine whether these parameters contribute to the risk of ischemic stroke. Thirty patients with POAG, 30 patients with OHT, and 30 age- and sex-matched healthy control subjects were included in this university hospital-based, cross-sectional, and observational study. Eyes with a greater degree of visual field loss and/or more severe optic disc damage were selected for the study in patients with POAG, whereas in patients with OHT and controls, the study eye was chosen randomly. The mean blood flow velocity and breath-holding index were measured in the middle cerebral artery ipsilaterally in patient and control groups, by using transcranial Doppler ultrasonography. The mean blood flow velocity and breath-holding indexes were significantly lower in patients with POAG than in the control group (all P<0.05). In the OHT group, the mean blood flow velocity and breath-holding indexes were not different from those in the control group. Patients with POAG have impaired vasodilation response to hypercapnia. Presumably, the neuronal changes and deterioration of the endothelium-mediated vasodilatation in patients with glaucoma may disrupt the regulation of arteries and potentially present functional insufficiency on vasoreactivity. Moreover, impaired cerebral vascular regulation may contribute to the increased risk of stroke in patients with POAG.

Angiotensin-Converting Enzyme Inhibitors Versus Angiotensin II Receptor Blockers

Angiotensin-Converting Enzyme Inhibitors Versus Angiotensin II Receptor Blockers