Endothelium-dependent Vasodilation Research Articles

Cardiovascular toxicities by calcineurin inhibitors: Cellular mechanisms behind clinical manifestations.

Calcineurin inhibitors (CNI), including cyclosporine A (CsA) and tacrolimus (TAC), are cornerstones of immunosuppressive therapy in solid organ transplant recipients. While extensively recognized for their capacity to induce nephrotoxicity, hypertension, and dyslipidemia, emerging reports suggest potential direct cardiovascular toxicities associated with CNI. Evidence from both invitro and invivo studies has demonstrated direct cardiotoxic impact of CNI, manifesting itself as induction of cardiomyocyte apoptosis, enhanced oxidative stress, inflammatory cell infiltration, and cardiac fibrosis. CNI enhances cellular apoptosis through CaSR via activation of the p38 MAPK pathway and deactivation of the ERK pathway, and enhancement of miR-377 axis. Although CNI could attenuate cardiac hypertrophy in certain animal models, CNI concurrently impaired systolic function, enhanced cardiac fibrosis, and increased the risk of heart failure. Evidence from invivo studies demonstrated that CNI prolong the duration of action potentials through a decrease in potassium current. CNI also exerted direct effects on endothelial cell injury, inducing apoptosis and enhancing oxidative stress. CNI may induce vascular inflammation through TLR4 via MyD88 and TRIF pathways. In addition, CNI affects vascular function by impairing endothelial-dependent vasodilation and promoting vasoconstriction. Clinical studies in transplant patients also revealed an increased incidence of cardiac remodeling. However, the evidence is constrained by the limited number of participants and potential confounding factors. Several studies indicate differing cardiovascular toxicity profiles between CsA and TAC, and these could be potentially due to their different interactions with calcineurin subunits and calcineurin-independent effects. Further studies are needed to clarify these mechanisms to improve cardiovascular outcomes for transplant patients with CNI.

TMAO Impairs Mouse Aortic Vasodilation by Inhibiting TRPV4 Channels in Endothelial Cells.

Trimethylamine oxide (TMAO) is an intestinal flora metabolite associated with risk of cardiovascular diseases. Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable ion channel that is essential for vasodilation and endothelial function. Currently, there are few studies on the effect of TMAO on TRPV4 channels. In the present study, Ca2+ imaging of vascular tissue showed that TMAO inhibited TRPV4-mediated Ca2+ influx into aortic endothelial cells in a dose-dependent manner. Furthermore, a whole-cell patch clamp assay showed that TMAO blocked TRPV4-mediated cation currents. Notably, results of aortic vascular tension measurement showed that TMAO impaired endothelium-dependent vasodilation in mouse aortic vessels through the TRPV4-NO pathway. Our results indicated that TMAO inhibited Ca2+ entry in endothelial cells and impaired vasodilation through the TRPV4-NO pathway in mice. These results provide scientific evidence for novel pathogenic mechanisms underlying the role of TMAO in cardiovascular disease.

Isoflurane increases the activity of the vascular matrix metalloproteinase-2 in non-pregnant rats and increases the nitric oxide metabolites in pregnancy.

Surgeries that require general anesthesia occur in 1.5-2% of gestations. Isoflurane is frequently used because of its lower possibility of affecting fetal growth. Therefore, we examined the isoflurane anesthesia-induced effects on maternal hemodynamic and vascular changes. We hypothesized that isoflurane would enhance endothelium-dependent vasodilation as a consequence of increased nitric oxide and decreased metalloproteinases (MMPs). Female rats (n=28) were randomized into 4 groups (7 rats/group): conscious (non-anesthetized) non-pregnant group, non-pregnant anesthetized group, conscious pregnant group, and pregnant anesthetized group. Anesthesia was performed on the 20th pregnancy day, and hemodynamic parameters were monitored. Nitric oxide metabolites, gelatinolytic activity of MMP-2 and MMP-9, and the vascular function were assessed. Isoflurane caused no significant hemodynamic changes in pregnant compared with non-pregnant anesthetized group. Impaired acetylcholine-induced relaxations were observed only in conscious non-pregnant group (by approximately 62%) versus 81% for other groups. Phenylephrine-induced contractions were greater in endothelium-removed aorta segments of both pregnant groups (with or without isoflurane) compared with non-pregnant groups. Higher nitric oxide metabolites were observed in anesthetized pregnant in comparison with the other groups. Reductions in the 75 kDa activity and concomitant increases in 64 kDa MMP-2 isoforms were observed in aortas of pregnant anesthetized (or not) groups compared with conscious non-pregnant group. Isoflurane anesthesia shows stable effects on hemodynamic parameters and normal MMP-2 activation in pregnancy. Furthermore, there were increases in nitric oxide bioavailability, suggesting that isoflurane provides protective actions to the endothelium in pregnancy.

Influence of the zoledronic acid accumulative effect on the microcirculation state in the rat periodontium

Objective. To determine the character of changes in the reactivity of rat periodontal microvessels depending on the multiplicity of zoledronic acid administration. Material and Methods. Wistar rats (n = 36) were divided into groups of 9 rats each. In group No. 1 (control), rats were injected with 0.9% sterile sodium chloride solution once a week for 3 weeks; in group No. 2, rats were injected once with zoledronic acid (ZA) once a week; in group No. 3, rats were injected intravenously with ZA once a week for 3 weeks; in group No. 4, rats were injected with ZA once a week for 6 weeks. ZA was administered at a dose of 0.18 mg/kg in 0.9% sterile sodium chloride solution in the volume of 1 ml/kg. The microcirculation parameters in the periodontium were determined before ZA administration and on the 3rd day after administration by laser Doppler flowmetry (LDF) and ultrasound high-frequency dopplerography (UHFD) methods. Periodontal vascular reactivity was determined using acetylcholine assay. Results. After ZA administration, the indices of microcirculatory vascular reactivity decreased in rats of groups No. 3 and No. 4 in comparison with the results obtained before ZA administration: at ultrasound examination the maximum increase of blood flow velocity was noted at the 2nd minute and amounted to 133±8,5, 112±7,8 %, respectively. In rats of group No. 2, the increase in blood flow velocity corresponded to the value of the control group. In LDF study, the maximal blood flow rates were lower than in the control group in rats administered the drug for 3 and 6 weeks, respectively. Conclusion. Zoledronic acid dose-dependently causes impaired vascular responsiveness and leads to a decrease in endothelium-dependent vasodilation.

Sex differences in skin microcirculatory vascular reactivity in experimental lipopolysaccharide-induced endotoxinemia

Bacterial lipopolysaccharide (LPS) plays a leading role in the development of a systemic inflammatory response and endogenous intoxication. However, the sex differences in the functional state of the microcirculatory bed in LPS-induced endotoxinemia have been poorly studied. Objective. To study the characteristics of skin microcirculatory vascular reactivity in experimental LPS-induced endotoxinemia in male and female rats. Material and methods. Modeling of endotoxinemia was performed by intraperitoneal injection of LPS of the cell wall of the bacterium Salmonella enterica to male and female Wistar stock rats. Two doses of LPS were used: 50 mg/kg and 10 mg/kg. We used laser Doppler flowmetry to evaluate skin perfusion before and after LPS injection, blood flow changes under test conditions with local contact hypothermia caused by a thermoelement. Results. 48 hours after LPS injection, a decrease in blood flow was observed, especially pronounced at a dose of LPS 50 mg/kg. During the test with local cooling of the skin, a change in the kinetics of the reaction was noted. Blood flow reduction was 75% (LPS 50 mg/kg) and 51% (LPS 10 mg/kg), statistically significantly different from the control groups. At the same time, the classic phenomenon of “cold vasodilation” observed in control rats was absent in all groups with the injection of LPS. Maximum perfusion after restoration of blood flow in females was achieved 3 times faster than in males (LPS 10 mg/kg). Conclusion. In experimental LPS-induced endotoxinemia, a dose-dependent decrease in skin perfusion was revealed. We obtained new data on the absence of pronounced “cold vasodilation” at local contact hypothermia. The results of the study indicate a violation of the mechanisms of neurogenic vasoconstriction and endothelium-dependent vasodilation, reflecting systemic disorders of microcirculation regulation. At the same time, the females showed a more positive dynamics of blood flow restoration in the test with local cooling of the skin, indicating a greater functional reserve and a more effective mechanism of autoregulation of the blood microcirculation system. A functional test with local contact cooling of the skin is highly informative for assessing vascular reactivity and preservation of the autoregulation mechanism of microcirculation in modeling endogenous intoxication

Nadir blood pressure responses to longer consecutive cardiac cycle sequences absent of sympathetic bursts are associated with popliteal endothelial-dependent dilation

PurposeThe nadir pressure responses to cardiac cycles absent of muscle sympathetic nerve activity (MSNA) bursts (or non-bursts) are typically reported in studies quantifying sympathetic transduction, but the information gained by studying non-bursts is unclear. We tested the hypothesis that longer sequences of non-bursts (≥8 cardiac cycles) would be associated with a greater nadir diastolic blood pressure (DBP) and that better popliteal artery function would be associated with an augmented reduction in DBP. MethodsResting beat-by-beat DBP (via finger photoplethysmography) and common peroneal nerve MSNA (via microneurography) were recorded in 39 healthy, adults (age 23.4 ± 5.3 years; 19 females). For each cardiac cycle absent of MSNA bursts, the mean nadir DBP (ΔDBP) during the 12 cardiac cycles following were determined, and separate analyses were conducted for ≥8 or < 8 cardiac cycle sequences. Popliteal artery endothelial-dependent (via flow-mediated dilation; FMD) and endothelial-independent vasodilation (via nitroglycerin-mediated dilation; NMD) were determined. ResultsThe nadir DBP responses to sequences ≥8 cardiac cycles were larger (−1.40 ± 1.27 mmHg) than sequences <8 (−0.38 ± 0.46 mmHg; p < 0.001). In adjusting for sex and burst frequency (14 ± 8 bursts/min), larger absolute or relative FMD (p < 0.01), but not NMD (p > 0.53) was associated with an augmented nadir DBP. This overall DBP-FMD relationship was similar in sequences ≥8 (p = 0.04–0.05), but not <8 (p > 0.72). ConclusionThe DBP responses to non-bursts, particularly longer sequences, were inversely associated with popliteal endothelial function, but not vascular smooth muscle sensitivity. This study provides insight into the information gained by quantifying the DBP responses to cardiac cycles absent of MSNA.

Endothelial Dysfunction under the Scope of Arterial Hypertension, Coronary Heart Disease, and Diabetes Mellitus using the Angioscan.

Cardiovascular disease and diabetes mellitus are among the leading causes of mortality. Our study evaluated endothelial function in patients with arterial hypertension, coronary heart disease, and diabetes mellitus. This study aimed to assess the degree of endothelial dysfunction in individuals with cardiovascular risk factors older than 55 years of age. A total of 112 patients were subdivided into three groups according to the existing disease; the first group consisted of 50 patients diagnosed with arterial hypertension (AH), the second group consisted of 30 patients with ischemic heart disease (IHD), and the third group included 20 patients with type 2 diabetes mellitus (DM). The control group included 12 practically healthy volunteers, comparable in age and sex. Exclusion criteria were age under 55 years, severe concomitant diseases in the acute phase or acute infectious diseases, and oncopathology. Considered factors of cardiovascular risk include dyslipidemia, elevated fasting blood glucose, hypertension, obesity, cigarette smoking, and heredity for CVD. Moreover, tests were conducted with the help of the device 'AngioScan-01' (LLC "AngioScan Electronics"). Endothelium-dependent vasodilation (EDV), the index of stiffness of the vascular wall (SI), and the atherogenic index (log (TG/HDL - C )) were evaluated. The analysis of the data obtained was carried out using the IBM SPSS Statistic program. In the control group, the atherogenic index was in the range of 3.34 (the normal is up to 3.5). The highest atherogenic index, 4.01, was observed in the DM group (differences with the control group are statistically significant). In the AH and IHD groups, the atherogenic index was 3.57 and 3.65, respectively. In the control group, the level of glycemia was 4.45 mmol/l. The highest level of fasting glucose was reported in the DM group, i.e., 6.7 mmol/l (differences with the control group were statistically significant). In the first and second groups, the fasting glucose level was 5.07 mmol/l and 5.08 mmol/l, respectively. In the control group, the mean EDV score was 2,056 ± 0.757 mm, and the lowest EDV in the DM group was 1.365 ± 0.413, but in the AH and IHD groups, it was also significantly reduced by 1.404 ± 0.440 and 1.377 ± 0.390, respectively. The stiffness index in the control group was 6.725 ± 0.776 m/s. In the DM group, this parameter was 8.258 ± 0.656 m/s; in the AH and IHD groups, it was 7.398 ± 1.330 m/s and 7.486 ± 0.816 m/s, respectively. In conclusion, the study of endothelial function using non-invasive angioscan reflects the influence of risk factors on the vascular wall. The most severe endothelial dysfunction is expressed in patients with diabetes. The results of endothelium-dependent vasodilation and the vascular wall stiffness index (SI) correspond to the scale of evaluation of the 10-year CVD mortality risk (SCORE). These results indicate a deterioration in the vascular ability to vasodilate in patients in response to mechanical deformation of the endothelium and the effect of NO on smooth muscle vascular cells.

Increased oxidative stress alters coronary microvascular tone in exercising swine with multiple comorbidities

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Dutch Cardiovascular Alliance Background/Objectives We have previously shown, in female swine that the combination of three cardiovascular risk factors (diabetes mellitus (DM), hypercholestolemia (HC) and chronic kidney disease (CKD)) induces systemic inflammation, oxidative stress, coronary endothelial dysfunction and impaired myocardial perfusion due to impaired nitric oxide (NO) bioavailability. In the present study we hypothesized that the reduced bioavailability of nitric oxide (NO) is the result of increased production of reactive oxygen species (ROS) and ROS scavenging will restore myocardial oxygen balance thereby improving myocardial perfusion. Methods 12 female swine, with DM (streptozotocin 3x50mg/kg iv), CKD (renal embolization), and HC (high fat, high sugar, high salt diet) and 9 female healthy swine on normal pig chow (Normal) were included. The effect of ROS scavenging on the coronary microvascular tone control was studied in vivo, at rest and during graded treadmill exercise before and after infusion of the ROS scavengers (MPG+Tempol). Additionally, vasodilation to bradykinin was studied in the presence of MPG and TEMPOL and after subsequent addition to catalase, in isolated left ventricle small coronary arteries, in vitro using wire-myography. Results 6 months of DM+HC+CKD resulted in hyperglycemia (18.0±1.3 vs 8.4±0.9mmol/L), hypercholesterolemia (13.4±2.1 vs 1.7±0.1mmol/l), renal dysfunction (plasma creatinine: 166±9 vs 119±3µmol/l), and systemic inflammation (TNFα: 63±8 vs 41±4pg/ml, all P&amp;lt;0.05) associated with impaired endothelium-dependent vasodilator response to bradykinin in vitro. Furthermore, myocardial oxidative stress was increased in DM+HC+CKD animals (8-isoprostane 13±1 vs 10±1pg/ml) and total antioxidant capacity was reduced (0.67±0.02 vs 0.72±0.01nmol Trolox eq./mg protein, both P&amp;lt;0.05). Surprisingly, in vivo ROS scavenging resulted in an even further increase in myocardial oxygen extraction in DM+HC+CKD while it had no effect in Normal, indicating the involvement of a vasodilator ROS (most likely H2O2) in the control of coronary microvascular tone. This was supported by increased activity of catalase in the myocardium of DM+HC+CKD animals (44±3 vs 31±4nmol/min/ml, both P&amp;lt;0.05) and the vascular relaxation response to bradykinin when catalase was added on top of the ROS scavenging in vitro. Conclusion In swine exposed for 6 months to multiple comorbidities, impaired myocardial perfusion is mediated by a loss of NO bioavailability due to increased oxidative stress which was partially compensated by increased H2O2-mediated coronary vasodilation.

Recovery of optimal vitamin D improves responsiveness to phosphodiesterase-5 inhibitors therapy in pulmonary arterial hypertension

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): R.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under Marie-Curie grant agreement Nº 847635. Introduction Vitamin D (vitD) deficiency is highly prevalent in patients with pulmonary arterial hypertension (PAH). Moreover, PAH-patients with lower levels of vitD have worse prognosis. We demonstrated that in animals with PAH and severe deficit of vitD, restoring vitD levels to an optimal range partially improves some pathophysiological features of PAH. Also, recent evidence suggests that vitD deficiency may cause insufficient response to phosphodiesterase-5 inhibitors (PDE5i), such as sildenafil, in some patients with PAH. Thus, in this study, we hypothesize that the recovery of optimal vitD levels in experimental PAH might help to improve responsiveness to PDE5i therapy. Methods Male Wistar rats were fed a vitD-free diet for five weeks and then received a single dose of Su5416 (20 mg/Kg) and were exposed to vitD-free diet and chronic hypoxia (10% O2) for three weeks to induce PAH. Following this, vitD deficient rats with PAH were housed in room air and divided into two groups: (a) daily tadalafil therapy (oral;10mg/kg) + continued vitD-free diet (n=9) or (b) daily tadalafil therapy (oral;10mg/kg) + single oral dose of 50,000 IU/Kg of vitD plus standard diet (n=9) for four weeks. Animals were then used for exercise capacity evaluation, invasive haemodynamic, pulmonary vascular analysis, and sample collection. Evolution of cardiac (dys)function was assessed by echocardiography. Results Recovering optimal vitD levels improved pulmonary endothelial function, measured by an increase in the endothelium-dependent vasodilator response to acetylcholine. It also increased the vasodilator response to sildenafil. Moreover, pulmonary small artery (&amp;lt;55 µm) remodeling was decreased in vitD-restored group, as measured by a decline in mean lumen/total ratio and mean medial thickness. In a morphometric analysis, vitD treatment attenuated increases in both right ventricle (RV) and right atrial hypertrophy, as well as the fulton index. VitD supplementation also improved the exercise capacity with increases seen in distance run, evaluated by endurance tests in a treadmill set. RV catheterization showed that vitD did not decreased the RV dysfunction, evaluated by end-systolic and end-diastolic pressure. Similar to the RV, no alterations were observed in pulmonary artery pressures. However, echocardiographic analysis revealed an improved pulmonary flow in the vitD-restored group, where pulmonary artery acceleration time normalized to ejection time ratio and pulmonary artery velocity-time integral were increased. It also improved tricuspid annular plane systolic excursion (TAPSE). Conclusion Altogether, these data suggest that in animals with PAH treated with tadalafil, restoring vitD levels to an optimal range improves some pathophysiological features of PAH. Therefore, in addition to recovery of optimal vitD status being indicated to restore calcium homeostasis in those PAH patients with severe deficiency, it might help to improve responsiveness to PDE5i.

Non-neuronal cell-derived acetylcholine, a key modulator of the vascular endothelial function in health and disease.

Vascular endothelial cells play an important role in regulating peripheral circulation by modulating arterial tone in the microvasculature. Elevated intracellular Ca2+ levels are required in endothelial cells to induce smooth muscle relaxation via endothelium-dependent mechanisms such as nitric oxide production, prostacyclin, and endothelial cell hyperpolarization. It is well established that exogenous administration of acetylcholine can increase intracellular Ca2+ concentrations, followed by endothelium-dependent vasodilation. Although endogenous acetylcholine's regulation of vascular tone remains debatable, recent studies have reported that endogenously derived acetylcholine, but not neuronal cell-derived acetylcholine, is a key modulator of endothelial cell function. In this minireview, we summarize the current knowledge of the non-neuronal cholinergic system (NNCS) in vascular function, particularly vascular endothelial cell function, which contributes to blood pressure regulation. We also discuss the possible pathophysiological impact of endothelial NNCS, which may induce the development of vascular diseases due to endothelial dysfunction, and the potential of endothelial NNCS as a novel therapeutic target for endothelial dysfunction in the early stages of metabolic syndrome, diabetes, and hypertension.

Exposure to occupational air pollution and vascular endothelial dysfunction in workers of the steel industry in Iran.

Air pollution is recognized as a risk factor for cardiovascular diseases; however, the precise underlying mechanisms remain unclear. This study investigated the impact of occupational air pollution exposure on endothelial function in workers within the steel industry. Specifically, we examined male employees in the coke-making division of the Isfahan Steel Company in Iran, as well as those in administrative roles with no known history of cardiovascular risk. Data on age, body mass index, duration of employment, blood pressure, fasting blood sugar, and lipid profile were collected. To assess endothelial function, flow-mediated dilation (FMD) was measured. The baseline brachial artery diameter was greater (mean difference [95% CI] = 0.068mm [0.008 to 0.128]), while the FMD was lower (mean difference [95% CI] = -0.908 % [-1.740 to -0.075]) in the coke-making group than in the control group. After controlling for potential confounding variables, it was observed that working in the coke-making sector of the industry was associated with lower FMD (F = 3.954, p = .049). These findings indicated that occupational air pollution exposure among workers in the steel industry is linked to impaired endothelium-dependent vasodilation.

How selective antagonists and genetic modification have helped characterise the expression and functions of vascular P2Y receptors.

Vascular P2Y receptors mediate many effects, but the role of individual subtypes is often unclear. Here we discuss how subtype-selective antagonists and receptor knockout/knockdown have helped identify these roles in numerous species and vessels. P2Y1 receptor-mediated vasoconstriction and endothelium-dependent vasodilation have been characterised using the selective antagonists, MRS2179 and MRS2216, whilst AR-C118925XX, a P2Y2 receptor antagonist, reduced endothelium-dependent relaxation, and signalling evoked by UTP or fluid shear stress. P2Y2 receptor knockdown reduced endothelial signalling and endothelial P2Y2 receptor knockout produced hypertensive mice and abolished vasodilation elicited by an increase in flow. UTP-evoked vasoconstriction was also blocked by AR-C118925XX, but the effects of P2Y2 receptor knockout were complex. No P2Y4 receptor antagonists are available and P2Y4 knockout did not affect the vascular actions of UTP and UDP. The P2Y6 receptor antagonist, MRS2578, identified endothelial P2Y6 receptors mediating vasodilation, but receptor knockout had complex effects. MRS2578 also inhibited, and P2Y6 knockout abolished, contractions evoked by UDP. P2Y6 receptors contribute to the myogenic tone induced by a stepped increase in vascular perfusion pressure and possibly to the development of atherosclerosis. The P2Y11 receptor antagonists, NF157 and NF340, inhibited ATP-evoked signalling in human endothelial cells. Vasoconstriction mediated by P2Y12/P2Y13 and P2Y14 receptors was characterised using the antagonists, cangrelor, ticagrelor, AR-C67085 and MRS2211 or PPTN respectively. This has yet to be backed up by receptor knockout experiments. Thus, subtype-selective antagonists and receptor knockout/knockdown have helped identify which P2Y subtypes are functionally expressed in vascular smooth muscle and endothelial cells and the effects that they mediate.

Translational Research of the Acute Effects of Negative Emotions on Vascular Endothelial Health: Findings From a Randomized Controlled Study.

Provoked anger is associated with an increased risk of cardiovascular disease events. The underlying mechanism linking provoked anger as well as other core negative emotions including anxiety and sadness to cardiovascular disease remain unknown. The study objective was to examine the acute effects of provoked anger, and secondarily, anxiety and sadness on endothelial cell health. Apparently healthy adult participants (n=280) were randomized to an 8-minute anger recall task, a depressed mood recall task, an anxiety recall task, or an emotionally neutral condition. Pre-/post-assessments of endothelial health including endothelium-dependent vasodilation (reactive hyperemia index), circulating endothelial cell-derived microparticles (CD62E+, CD31+/CD42-, and CD31+/Annexin V+) and circulating bone marrow-derived endothelial progenitor cells (CD34+/CD133+/kinase insert domain receptor+ endothelial progenitor cells and CD34+/kinase insert domain receptor+ endothelial progenitor cells) were measured. There was a group×time interaction for the anger versus neutral condition on the change in reactive hyperemia index score from baseline to 40 minutes (P=0.007) with a mean±SD change in reactive hyperemia index score of 0.20±0.67 and 0.50±0.60 in the anger and neutral conditions, respectively. For the change in reactive hyperemia index score, the anxiety versus neutral condition group by time interaction approached but did not reach statistical significance (P=0.054), and the sadness versus neutral condition group by time interaction was not statistically significant (P=0.160). There were no consistent statistically significant group×time interactions for the anger, anxiety, and sadness versus neutral condition on endothelial cell-derived microparticles and endothelial progenitor cells from baseline to 40 minutes. In this randomized controlled experimental study, a brief provocation of anger adversely affected endothelial cell health by impairing endothelium-dependent vasodilation.

Purinergic regulation of pulmonary vascular tone.

Purinergic signaling is a crucial determinant in the regulation of pulmonary vascular physiology and presents a promising avenue for addressing lung diseases. This intricate signaling system encompasses two primary receptor classes: P1 and P2 receptors. P1 receptors selectively bind adenosine, while P2 receptors exhibit an affinity for ATP, ADP, UTP, and UDP. Functionally, P1 receptors are associated with vasodilation, while P2 receptors mediate vasoconstriction, particularly in basally relaxed vessels, through modulation of intracellular Ca2+ levels. The P2X subtype receptors facilitate extracellular Ca2+ influx, while the P2Y subtype receptors are linked to endoplasmic reticulum Ca2+ release. Notably, the primary receptor responsible for ATP-induced vasoconstriction is P2X1, with α,β-meATP and UDP being identified as potent vasoconstrictor agonists. Interestingly, ATP has been shown to induce endothelium-dependent vasodilation in pre-constricted vessels, associated with nitric oxide (NO) release. In the context of P1 receptors, adenosine stimulation of pulmonary vessels has been unequivocally demonstrated to induce vasodilation, with a clear dependency on the A2B receptor, as evidenced in studies involving guinea pigs and rats. Importantly, evidence strongly suggests that this vasodilation occurs independently of endothelium-mediated mechanisms. Furthermore, studies have revealed variations in the expression of purinergic receptors across different vessel sizes, with reports indicating notably higher expression of P2Y1, P2Y2, and P2Y4 receptors in small pulmonary arteries. While the existing evidence in this area is still emerging, it underscores the urgent need for a comprehensive examination of the specific characteristics of purinergic signaling in the regulation of pulmonary vascular tone, particularly focusing on the disparities observed across different intrapulmonary vessel sizes. Consequently, this review aims to meticulously explore the current evidence regarding the role of purinergic signaling in pulmonary vascular tone regulation, with a specific emphasis on the variations observed in intrapulmonary vessel sizes. This endeavor is critical, as purinergic signaling holds substantial promise in the modulation of vascular tone and in the proactive prevention and treatment of pulmonary vascular diseases.

WNK kinase, ion channels and arachidonic acid metabolites choreographically execute endothelium-dependent vasodilation

The smooth muscle-walled blood vessels control blood pressure. The vessel lumen is lined by an endothelial cell (ECs) layer, interconnected to the surrounding smooth muscle cells (SMCs) by myoendothelial gap junctions. Gap junctions also maintain homo-cellular ECs-ECs and SMCs-SMCs connections. This gap junction network nearly equalises both cells' membrane potential and cytosolic ionic composition, whether in resting or stimulated conditions. When acetylcholine (ACh) activates ECs M3 receptors, a complex signalling cascade involving second messengers and ion channels is triggered to induce vasodilation.

TNF-TNFRI interaction impairs endothelial calcium signaling and elevates blood pressure in obesity

Endothelial dysfunction in small arteries plays a pivotal role in obesity-induced hypertension. Recent investigations have unveiled the detrimental impact of peroxynitrite, a reactive nitrogen species, on endothelium calcium signaling and vasodilation. Vascular inflammation has emerged as a crucial contributor to the pathogenesis of cardiovascular disorders. In this regard, the inflammatory cytokine, tumor necrosis factor (TNF), has been linked to peroxynitrite formation and endothelial dysfunction. Although TNF signaling in cardiovascular disorders is mainly attributed to immune cells, recent studies suggest that endothelial cells (ECs) and smooth muscle cells (SMCs) also produce TNF. We hypothesized that TNF derived from the vascular wall acts locally to inhibit endothelium-dependent vasodilation in obesity. Male C57BL6J mice fed a high-fat diet (HFD, 60% kcal fat) for 14 weeks showed higher blood pressures that normal chow diet (NCD)-fed mice. Flow cytometry and mRNA expression studies showed an increase in TNF levels in freshly isolated SMCs from small mesenteric arteries (MAs) in HFD mice compared to NCD mice. However, TNF levels in ECs were not different between HFD or NCD mice. Control and EC-specific TNF knockout (TNFECKO) mice showed a similar increase in blood pressure after HFD feeding. However, HFD feeding failed to elevate blood pressure in SMC-specific TNF knockout (TNFSMCKO) mice, suggesting a critical role for SMC TNF in blood pressure elevation in HFD mice. Both TNFSMCKO and TNFECKO showed a similar increase in body weight after HFD feeding when compared to control mice, suggesting that differences in weight gain did not contribute to lower blood pressure in obese TNFSMCKO mice. The pro-inflammatory effects of TNF are primarily attributed to TNF receptor-I (TNFRI) signaling. Therefore, we postulated that TNF released from SMCs acts locally on EC TNFRI to impair endothelium-dependent vasodilation. EC-specific TNFRI deletion (TNFRIECKO) reduced blood pressure, whereas SMC-specific TNFRI deletion (TNFRISMCKO) had no effect on blood pressure after HFD feeding. These findings collectively underline the critical role of SMC-derived TNF and endothelial TNFRI in driving blood pressure elevation in diet-induced obesity. Consistent with these data, endothelium-dependent vasodilation in response to acetylcholine markedly improved in obese TNFSMCKO and TNFRIECKO mice compared to obese control mice. Previous studies showed that decreased Ca2+ influx through endothelial TRPV4 (transient receptor potential vanilloid 4) channels contributes to endothelia dysfunction and blood pressure elevation in obese mice. The activity of TRPV4 channels was improved in ECs from HFD-fed TNFSMCKO and TNFRIECKO mice. Additionally, the levels of endothelial peroxynitrite were diminished in obese TNFSMCKO and TNFRIECKO mice, ameliorating the peroxynitrite-dependent impairment of endothelial function. Furthermore, treatment with a selective TNFRI signaling inhibitor (R7050, 10 mg/kg, intraperitoneally, once daily for 14 days) restored blood pressure to normal levels in HFD-fed obese mice but had no effect on the blood pressure in NCD-fed mice. R7050 treatment also restored endothelium-dependent dilation of MAs and the activity of TRPV4 channels in ECs. Collectively, our findings identify a critical role of local TNF-TNFRI signaling in the vascular wall in obesity-induced impairment of endothelial function and blood pressure elevation. The National Institutes of Health to SKS (HL146914, HL142808, and HL147555). This is the full abstract presented at the American Physiology Summit 2024 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.

Dietary Effect on Peripheral and Cerebral Vascular Function in Adults with Non-Alcoholic Fatty Liver Disease

Objective: Non-alcoholic fatty liver disease (NAFLD) is a recognized independent risk factor for cardiovascular and cerebrovascular dysfunction. The present study evaluated the effect of dietary interventions on peripheral and cerebral vascular function in individuals with NAFLD. Methods: We studied 30 middle-aged adults (55±9 years) with NAFLD or with elevated NAFLD risk (with prediabetes symptoms). Liver fat content was assessed via 1H magnetic resonance spectroscopy. NAFLD was defined as liver fat proton density fat fraction (PDFF) exceeding 5%. Participants were randomly assigned to a low-carbohydrate diet (carbohydrate intake &lt;30 g/d) or a low-calorie diet (30% calorie intake reduction). Arterial stiffness (via brachial-ankle pulse wave velocity-baPWV), carotid artery intima-media thickness (IMT), endothelium-dependent vasodilation (via flow-mediated dilation-FMD), cerebrovascular reactivity (CVR) in the middle cerebral artery (MCA), and blood concentrations of cardiovascular risk factors were measured before and after a two-week dietary intervention. Results: Participants with NAFLD represented 70% of the current cohort. Following the dietary interventions, participants had significant reductions in body weight (95%CI [-3.22, -1.41 kg]) and fat mass (95%CI [-1.64, -0.56 kg]), accompanied by decreased liver fat content (95%CI [-2.62, -0.79%]). These changes were only evident in the NAFLD group with no significant differences between the two dietary interventions. Systolic and diastolic blood pressure as well as pulse pressure significantly decreased in both NAFLD and non-NAFLD groups. Total cholesterol (95%CI [-22.2, -1.5 mg/dL]) and triglyceride (95%CI [-30.4, -0.9 mg/dL]) concentrations decreased in those with NAFLD assigned to the low-carbohydrate diet. baPWV decreased (95%CI [-78.6, -12.4 cm/s]) only in individuals with NAFLD assigned to the low-calorie diet. FMD significantly increased (95%CI [0.5, 5.1%]) only in individuals with NAFLD assigned to the low-carbohydrate diet. Lower baseline liver fat content was associated with greater improvement in FMD (r=-0.60, p=0.008) in the NAFLD group. Carotid IMT and cerebrovascular parameters (e.g., pulsatility index, CVR, MCA blood flow velocity) remained unchanged in any groups. Changes in vascular function were not associated with the corresponding changes in liver fat content. Conclusion: The two-week dietary intervention involving either a low-carbohydrate or low-calorie diet elicited significant reductions in liver fat content and improvements in peripheral arterial stiffness and endothelium-dependent vasodilation in adults with NAFLD. UT Aging Initiatives. This is the full abstract presented at the American Physiology Summit 2024 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.

Prefrontal-medullary Circuitry Impacts Sex-specific Microvascular Function Following Chronic Stress

Vascular dysfunction is a prominent factor underlying cardiovascular disease, the leading cause of death worldwide. Additionally, chronic stress contributes to cardiovascular pathologies in a sex-dependent manner. However, the neurobiological mechanisms mediating the sex-specific impact of chronic stress on vascular function are not known. Our previous studies found that the prefrontal infralimbic cortex (IL)-rostral ventrolateral medulla (RVLM) circuit inhibits sympathetic and endocrine responses to stress; therefore, the current study tested the hypothesis that the IL-RVLM circuit is necessary to mitigate microvascular dysfunction following chronic stress. To this end, an intersectional genetic approach was used to induce Cre-dependent expression of tetanus toxin light chain and inhibit neurotransmitter release from RVLM-projecting IL neurons in male and female rats. Rats were then exposed to 2 weeks of chronic variable stress (CVS) or remained unstressed. Left ventricle structure was assessed by echocardiography and microvascular function was subsequently assessed by resistance arteriole pressure myography. Arteriole myogenic tone, endothelial-independent vasoconstriction, as well as endothelial-dependent vasodilation and vasoconstriction were determined at both normotensive (70 mmHg) and hypertensive (120 mmHg) pressures. Our results indicate that heart size and ventricular thickness were impacted in a sex-dependent manner. Circuit inhibition increased heart index in females regardless of stress. In males, circuit inhibition reduced ventricular wall thickness in diastole. Microvasculature also exhibited sex-dependent function. Following CVS, males had increased myogenic tone compared to females. Circuit inhibition also differentially impacted vasodilation in males and females. In chronically stressed females, circuit inhibition increased endothelial-dependent vasodilation at both normotensive and hypertensive pressures and normotensive endothelial-independent relaxation. These changes indicate that chronic stress leads to female microvascular dysfunction that is exacerbated by IL-RVLM inhibition. Chronically stressed males had no changes in normotensive vasodilation. However, with elevated pressure, circuit-inhibited CVS males had increased endothelial-dependent vasodilation. In contrast, unstressed males with circuit inhibition had decreased endothelial-dependent vasodilation at 120 mmHg, indicating that the male IL-RVLM circuit may be necessary for vascular function during acute hypertensive events. Broadly, these results support the hypothesis that the IL-RVLM circuit is necessary for appropriate vascular function and that circuit inhibition and chronic stress lead to sex-specific responses that may differentially impact the progression of cardiovascular disease. NIH R01 HL150559 (B.Myers) NIH F30 OD032120 (C. Dearing). This is the full abstract presented at the American Physiology Summit 2024 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.

Evidence of Premature Vascular Dysfunction in Young Adults who Regularly Use E-cigarettes and the Impact of Usage Length

Background: Electronic (e-) cigarettes are increasingly popular novel tobacco products on the US market. Traditional tobacco products are well known to cause vascular dysfunction, one of the earliest indicators of cardiovascular disease (CVD) development. Despite the popularity of e-cigarettes, little is known about the effect of regular e-cigarette use on vascular function. The purpose of this study was to investigate the impact of regular e-cigarette use on vascular function and cardiovascular health in young, healthy adults. Methods: Twenty-one regular users of e-cigarettes (ECU, age: 23±3 y.) and twenty-one demographically matched non-users (NU, age: 25±5 y.) completed this study. Vascular health was assessed in the cutaneous microcirculation through different reactivity tests to evaluate overall functionality as well as endothelium-dependent vasodilation (EDD) and endothelium-independent vasodilation (EID). Macrovascular function was assessed using flow-mediated dilation (FMD). Results: Our results suggest that regular users of e-cigarettes present with premature microvascular impairment compared to non-users. Specifically, they exhibit lower hyperemic ( p=0.003), thermal ( p=0.010), and EDD ( p=0.004) responses. No differences in EID between the groups were identified. We also identified that individuals who use e-cigarettes for longer than three years also present with systemic manifestations, as observed by significantly reduced macrovascular ( p=0.002) and microvascular ( p≤0.044) function. Conclusions: Our novel data suggests that young, apparently healthy, regular users of e-cigarettes present with premature vascular dysfunction in the microcirculation compared to non-users. We have also identified systemic vascular dysfunction affecting both the micro and macrovasculature in those young individuals who used e-cigarettes for longer than three years. Taken together, these findings associate regular e-cigarette use with premature vascular dysfunctions and adverse cardiovascular outcomes. Supported in part by a Rapid Response Project NIDA/FDA (PRM). This is the full abstract presented at the American Physiology Summit 2024 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.

Stronger vasoconstriction and weaker vasodilation in mesenteric arteries of Ossabaw than Göttingen minipigs before manifestation of metabolic syndrome

The metabolic syndrome predisposes and contributes to the development and progression of atherosclerosis. The minipig strain “Ossabaw” is characterized by a polygenic predisposition to develop metabolic syndrome and diffuse atherosclerosis in response to a hypercaloric atherogenic diet. The aim of this study was to investigate whether Ossabaw minipigs exhibit an altered vasomotor function even before they develop their diseased phenotype. Mesenteric arteries of adult Ossabaw (n=30) and Göttingen minipigs (n=40), a pig strain without genetic predisposition to a metabolic syndrome, were harvested postmortem, dissected, and mounted on a myograph for isometric force measurements. Maximal vasoconstriction to smooth muscle cell depolarization with potassium chloride (KClmax) was repeatedly induced (twice 0.6×10−1 mol/L and twice 1.2×10−1 mol/L). Cumulative concentration-response curves were determined in response to 1×10−9 -1×10−4 mol/L norepinephrine. Endothelium-dependent and -independent vasodilation were analyzed in response to carbachol and nitroprusside, respectively (1×10−9 - 1×10−4 mol/L, each) after pre-constriction by norepinephrine. The baseline diameter of mesenteric arteries from Ossabaw minipigs was smaller than that from Göttingen minipigs (329±20 vs. 435±11 μm), and mesenteric arteries of Ossabaw minipigs developed a higher baseline force of contraction than mesenteric arteries of Göttingen minipigs (6.2±0.7 vs. 3.6±0.3 mN). The maximal vasoconstrictor response to KCl was comparable between the minipig strains. Vasoconstriction in response to norepinephrine was more pronounced in Ossabaw than in Göttingen minipigs (143±9 vs. 108±6% KClmax). Endothelium-dependent vasodilation (46.4±5.5 vs. 16.0±3.0% of norepinephrine-induced preconstriction) and -independent vasodilation (36.7±4.9 vs. 2.3±0.6% of norepinephrine-induced preconstriction) were less pronounced in Ossabaw than in Göttingen minipigs. Neither the differences in baseline diameter nor in baseline developed force of contraction had any effect on the above data, as analyzed in retrospectively matched subsets of mesenteric arteries with a comparable baseline diameter or a comparable baseline developed force of contraction, respectively. Even before the development of metabolic syndrome, vasomotor function is shifted to more vasoconstriction and less vasodilation in Ossabaw minipigs, suggesting a genetic predisposition for the early development of vascular dysfunction. Thus, Ossabaw minipigs may be a suitable model to reflect the human situation of a heterogeneous, genetically determined primordial risk constellation for vascular dysfunction. This work was supported by the German Research Foundation [SFB 1116 B08 to G.H. and P.K.] and the European COST ACTION in CARDIOPROTECTION [CA16225 to G.H. and IG16225 to G.H. and P.K.]. This is the full abstract presented at the American Physiology Summit 2024 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.