Endothelium-independent Vasodilation Research Articles

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.

Oxidation of the actin cytoskeleton regulator cofilin-1 as a mediator of endothelial stiffening and dysfunction in type 2 diabetes

Vascular disease is a feature of type 2 diabetes (T2D) that is caused in part by oxidative stress and endothelial dysfunction. An emerging instigator of endothelial dysfunction is stiffening of the cell, which is mediated by enhanced polymerization of filamentous actin (F-actin). Actin polymerization is regulated by cofilin-1, an actin severing protein that can be phosphorylated or oxidized, leading to its inactivation and loss of severing capability. Yet, the mechanisms contributing to endothelial stiffening in T2D remain largely unknown. Herein, we tested the hypothesis that endothelial stiffening in T2D is mediated by inactivation of cofilin-1, leading to actin polymerization. In support of this hypothesis, human umbilical vein endothelial cells (HUVECs) treated with plasma from subjects with T2D, and the aortic endothelium of diabetic mice (db/db), demonstrate increased cellular stiffness and F-actin presence. Of note, these findings were not associated with enhanced phosphorylation of cofilin-1, suggesting that its inactivation may instead occur through oxidation. Indeed, we show that cofilin-1 can be oxidized by H2O2, a strong oxidizing agent, and that exposure of HUVECs to H2O2 induces F-actin formation. These findings implicate oxidation and inactivation of cofilin-1 as a putative driver of endothelial F-actin formation and cellular stiffening. In further support of the notion that inactivation of cofilin-1 in endothelial cells promotes cytoskeletal remodeling, we show that genetic silencing or pharmacological inhibition of LIM kinase-1 (LIMK-1), a key enzyme responsible for phosphorylating and thus inactivating cofilin-1, reduces F-actin content and cellular stiffness. Congruently, we show that LIMK inhibition reduces endothelial stiffness in aortic explants from db/db mice. It is conceivable that increased endothelial actin polymerization and stiffening impact vasomotor function. As proof-of-concept, we show that intraluminal exposure of isolated arteries to jasplakinolide, a pharmacological inducer of actin polymerization, impairs endothelial-dependent vasodilation, as assessed via flow-mediated dilation (FMD), while endothelium-independent vasodilation remains unaffected. Conversely, cytochalasin D, an inhibitor of actin polymerization, improves FMD, without influencing endothelium-independent vasodilation. Taken together, these findings suggest the existence of a potential new paradigm of T2D-associated endothelial dysfunction whereby oxidative stress inactivates cofilin-1, contributing to F-actin-dependent endothelial stiffening. Moreover, this work supports the idea that LIMK-1 may be considered a potential target for reducing cofilin-1 inactivation and reversing endothelial stiffening in T2D. Funding: R01HL151384, R01HL153264, R01HL137769, and AHA23PRE1020897. 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.

Sensitized serotonin-mediated vasodilation in a mouse model of carcinoid disease

Background: Carcinoid tumors secrete vasoactive hormones such as serotonin that impact cardiovascular function. In consequence, patients with metastatic carcinoid disease are at risk for carcinoid syndrome, characterized by profound cutaneous flushing, hypotension, and syncope. Our recent work demonstrates that in patients with carcinoid metastases, higher serotonin levels are associated with lower vascular resistance. However, it is unknown if the vascular sensitivity to serotonin is affected by carcinoid disease. The receptor that mediates the potential vasodilatory effects of serotonin in carcinoid disease is also unknown. Therefore, we hypothesize that serotonin-mediated vasodilation is increased by carcinoid metastases. To test this, we assessed vascular reactivity to serotonin ex vivo in a mouse model of carcinoid disease. Methods: J:Nu nude mice (10 weeks) received intrasplenic injection of 2x107 BON1 neuroendocrine tumor cells (BON1, n=5) or PBS-vehicle (VEH, n=5), and were monitored for 10 weeks to allow the development of liver carcinoid metastases. Animals were then euthanized, and mesentery arteries were harvested. Isolated, pressurized mesentery arteries were pre-constricted with phenylephrine. The dose-response vasodilation to serotonin and acetylcholine was measured. These dose responses were repeated in the presence of 5-HT2B receptor antagonist LY272015 or nitric oxide synthase inhibitor L-NAME. Endothelium-independent vasodilation to sodium nitroprusside was also assessed. Data are mean ± SEM. Results: Mesentery arteries from BON1 mice had a greater vasodilation in response to serotonin compared with arteries from VEH mice (65±6% vs. 44±8%, p=0.04). Incubation with L-NAME partially inhibited the vasodilation to serotonin in the BON1 arteries (42±10%, p=0.04), but not in VEH arteries (30±11%, p=0.17). LY272015 did not affect the serotonin-induced vasodilation in the BON1 or VEH arteries (BON1: 52±10%, p=0.14, VEH: 49±17%, p=0.39). In contrast to serotonin, the vasodilation to acetylcholine did not differ between BON1 and VEH arteries (77±9% vs. 61±16%, p=0.19). There were also no differences in the vasodilation to sodium nitroprusside between groups (p=0.42). Arteries from BON1 mice had a trend for greater vasoconstriction in phenylephrine compared with VEH mice (51±7% vs. 37±9%, p=0.06). Conclusions: These findings demonstrate that serotonin-mediated vasodilation is sensitized in a mouse model of carcinoid disease. This is potentially accompanied by enhanced α-adrenergic-mediated vasoconstriction, which may be a compensatory mechanism in response to sensitized vasodilatory mechanisms. Western University of Health Sciences Intramural Grant (BHM). 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.

The role of T-type calcium channels in elderly human vascular function: A pilot randomized controlled trial.

Endothelial dysfunction develops with age and may precede cardiovascular disease. Animal data suggest that T-type calcium channels play an important role in endothelial function, but data from humans are lacking. This study included 15 healthy, sedentary, elderly males for a double blinded, randomized controlled trial. For 8weeks, they were given 40mg/day of either efonidipine (L- and T-type calcium channel blocker (CCB)) or nifedipine (L-type CCB). Vascular function was evaluated by graded femoral arterial infusions of acetylcholine (ACh; endothelium-dependent vasodilator) and sodium nitroprusside (endothelium-independent vasodilator) both with and without co-infusion of N-acetylcysteine (NAC; antioxidant). We measured leg blood flow and mean arterial pressure and calculated leg vascular conductance to evaluate the leg vascular responses. Despite no significant change in blood pressure in either group, we observed higher leg blood flow responses (Δ 0.43±0.45l/min, P=0.006) and leg vascular conductance (Δ 5.38±5.67ml/min/mmHg, P=0.005) to intra-arterial ACh after efonidipine, whereas there was no change in the nifedipine group, and no differences between groups. We found no upregulation of endothelial nitric oxide synthase in vastus lateralis muscle biopsies within or between groups. Smooth muscle cell responsiveness was unaltered by efonidipine or nifedipine. Intravenous co-infusion of NAC did not affect endothelium-dependent vasodilatation in either of the CCB groups. These results suggest that 8weeks' inhibition of T- and L-type calcium channels augments endothelium-dependent vasodilatory function in healthy elderly males. Further studies are required to elucidate if T-type calcium channel inhibition can counteract endothelial dysfunction.

Evidence of premature vascular dysfunction in young adults who regularly use e-cigarettes and the impact of usage length

BackgroundElectronic (e-) cigarettes are increasingly popular tobacco products on the US market. Traditional tobacco products are known to cause vascular dysfunction, one of the earliest indicators of cardiovascular disease (CVD) development. However, 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.MethodsTwenty-one regular users of e-cigarettes (ECU) and twenty-one demographically matched non-users (NU) completed this study. Vascular health was assessed in the cutaneous microcirculation through different reactivity tests to evaluate overall functionality, endothelium-dependent vasodilation (EDD), and endothelium-independent vasodilation (EID). Macrovascular function was assessed using flow-mediated dilation (FMD).ResultsOur results suggest that regular users of e-cigarettes present with premature microvascular impairment when 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 3 years also present with systemic manifestations, as observed by significantly reduced macrovascular (p = 0.002) and microvascular (p ≤ 0.044) function.ConclusionsOur novel data suggests that young, apparently healthy, regular users of e-cigarettes present with premature vascular dysfunction in the microcirculation when 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 3 years. Taken together, these findings associate regular e-cigarette use with premature vascular dysfunctions and adverse cardiovascular outcomes.

Роль корекції ендотеліальної дисфункції в комплексній профілактиці гіпертензивних ускладнень вагітності

Purpose - to study the effect of correction of endothelial dysfunction by the introduction of L-arginine in the comprehensive prevention of the development of severe hypertensive disorders in pregnant women. Materials and methods. The division into groups was carried out indiscriminately following the prescribed bath. 27 women reached the 1st group, who, in addition to basic prevention of preeclampsia (small doses of aspirin for 12 days, calcium supplement 1000 mg per dose for 16 years), took Tivortin until conception and p. It's an hour of urgency; up to the 2nd group - 54 women who did not receive basic prevention of preeclampsia. The control group (3) consisted of 16 healthy women with physiological changes in vagusity. Participants of the 1st group, during the hour of stay in the hospital, took L-arginine internally (iv) (4 g) + 2 teaspoons 2 times (4 g) per os per dose 40 minutes before admission, then 3 teaspoons spoons 2 times (6 g per dose). The average intensity of the droplets became 6. The function of the endothelium was evaluated according to the universally recognized non-invasive cuff test method, which is based on the principle of ultrasound assessment of the change in the diameter of the brachial artery in response to the restoration of blood flow in it after short-term compression of the upper limb with a cuff. Physical condition and endurance were assessed using the generally accepted 6-minute walk method. The quality of life in pregnant women who had experienced severe preeclampsia in the past was assessed in stages - according to the health-related quality of life (HRQoL) scale and the scale created by the World Health Organization (WHOQOL-BREF). Results. Arterial hypertension and preeclampsia are based on changes in endothelium-dependent vasodilatation. A positive effect on the function of the endothelium significantly improves indicators of physical well-being and quality of life. When conducting a test with a 6-minute walk in the Group 1, better indicators were found than in the Group 2 (respectively, 409±23 m vs. 381±32 m, p<0.05), this indicator in the control group was 473±32 m (p<0.05 according to the Groups 1 and 2). However, this indicator significantly improved in pregnant women of the Group 1 after intravenous administration of L-arginine: 441±12 m (p<0.05 compared to the indicator before intravenous administration). According to the assessment of the quality of life of pregnant women of the studied groups, it should be noted that the quality of life indicators in all domains are significantly lower in women of the Group 1, which is associated with significantly worse anamnesis data of such women, significant concern about the results of the next pregnancy. When evaluating indicators of endothelium-dependent and endothelium-independent vasodilatation, it was found that in the group of women who received L-arginine preconceptionally, in the 1st trimester, the indicator before intravenous IV administration was 5.09±0.44, and after - 8.21±0.24, which indicates a significant improvement in endothelium-dependent vasodilation indicators (by 49.1%) 28-32 weeks, there are also no births of children with a body weight of less than 1500 g. Conclusions. In the group of high-risk pregnant women, the use of L-arginine in the complex prevention of preeclampsia allows to reduce the risks of early severe preeclampsia, to reduce the medication burden of two- and three-component hypotensive therapy. An increase in physical endurance, quality of life, and improvement in pregnancy outcomes are due to a positive effect on the function of the endothelium through the optimization of endothelium-dependent vasodilatation associated with the provision of the L-arginine substrate for the full synthesis of nitric oxide. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

Efficacy of Allopurinol in Improving Endothelial Dysfunction: A Systematic Review and Meta-Analysis.

Endothelial dysfunction has been implicated in various cardiovascular disorders as the initial pathology. Allopurinol has been shown to improve endothelial dysfunction in patients with gout, but its effect on cardiovascular patients is unclear. We aim to assess allopurinol efficacy in improving endothelial dysfunction overall and in different disease states including but not limited to heart failure, chronic kidney disease, ischemic heart disease METHODS: We conducted a literature search of PubMed, Cochrane's Central Library, and Scopus until December 2022, including randomized controlled trials and double-arm observational studies. The primary outcome measure was endothelial function assessed by change in flow mediated dilation (FMD) RESULTS: Our meta-analysis included 22 studies with a total of 1472 patients. Our pooled analysis shows that allopurinol significantly improved FMD (WMD=1.46%, 95% CI [0.70, 2.22], p < 0.01) compared to control. However, there was no significant difference between allopurinol and control for endothelial-independent vasodilation measured by forearm blood flow (WMD=0.10%, 95% CI [- 0.89, 0.69], p = 0.80). Subgroup analysis indicated that the effect of allopurinol on FMD was more significant in diabetic and congestive heart failure patients. While allopurinol may improve endothelial function in various patient populations, further high-quality randomized controlled trials are needed to determine its efficacy in preventing cardiovascular disease exacerbation.

Seasonal variations in endothelium-dependent flow-mediated vasodilation and endothelium-independent nitroglycerine-induced vasodilation.

Cardiovascular mortality has been shown to vary seasonally. However, it has not been determined whether vascular function is affected by the season. The purpose of this study was to investigate the associations of vascular function with season and outdoor temperature. Between April 2007 and March 2022, measurements of flow-mediated vasodilation (FMD) of the brachial artery as an index of endothelial function and nitroglycerine-induced vasodilation (NID) as an index of endothelium-independent vasodilation were performed in 2190 subjects. There was no significant seasonal difference in FMD (spring, 3.9 ± 3.1%; summer, 3.5 ± 3.0%; fall, 3.7 ± 3.0%; winter, 3.6 ± 3.2%; P = 0.14). There was no significant correlation between FMD and daily mean outdoor temperature (r = -0.02, P = 0.25). Multivariate analyses revealed that neither season (β = -0.020, P = 0.31) nor outdoor temperature (β = 0.005, P = 0.81) was significantly associated with FMD after adjustment for other confounding factors. There were significant seasonal differences in NID (spring, 12.8 ± 6.3%; summer, 12.0 ± 6.1%; fall, 11.7 ± 6.1%; winter, 12.3 ± 5.9%; P = 0.02). However, multivariate analysis revealed that there was no significant association between season and NID after adjustment for other confounding factors (β = -0.012, P = 0.56). There was no significant correlation between NID and daily outdoor mean temperature (r = -0.03, P = 0.17). Multivariate analysis revealed that outdoor temperature was not significantly associated with NID (β = -0.006, P = 0.78). There was no significant association of FMD or NID with season or outdoor temperature, suggesting that it is not necessary to take into account the effects of season and outdoor temperature on vascular function when interpreting the results of FMD and NID measurements. Public trials registry number: UMIN000039512.

Genetic background influences arterial vasomotor function in male and female mice.

The purpose of this study was to assess the influence of genetic background and sex on nitric oxide (NO)-mediated vasomotor function in arteries from different vascular territories. Vasomotor function was assessed in thoracic aorta, abdominal aorta, carotid arteries, and femoral arteries from the following mouse strains: SJL/J, DBA/2J, NZW/LacJ, and C57BL/6J. Contractile responses were assessed using the α1-adrenergic receptor agonist phenylephrine (PE, 10-9 -10-5 M). Vasorelaxation responses were assessed by examining relaxation to an endothelium-dependent vasodilator acetylcholine (ACh, 10-9 -10-5 M) and an endothelium-independent vasodilator sodium nitroprusside (SNP, 10-9 -10-5 M). To evaluate the role of NO, relaxation responses to ACh and SNP were assessed in the absence or presence of a nitric oxide synthase inhibitor (N omega-nitro-l-arginine methyl ester hydrochloride: 10-4 M). Vasomotor responses to ACh and PE varied across strains and among the arteries tested with some strains exhibiting artery-specific impairment. Results indicated some concentration-response heterogeneity in response to ACh and SNP between vessels from females and males, but no significant differences in responses to PE. Collectively, these findings indicate that vasomotor responses vary by genetic background, sex, and artery type.

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.

Functional State of the Mesenteric Arteries and Vessels of the Skin Microcirculation Bed in Rats with Experimental Kidney Dysfunction

Chronic kidney disease is accompanied by cardiovascular complications, including endothelial dysfunction, arterial hypertension, and atherosclerosis. The aim of this work is to compare the reactivity of the vessels of the microcirculatory bed (MCR) of the skin, assessed by laser Doppler flowmetry (LDF) and mesenteric arteries in rats with resection of 5/6 of the mass of the kidneys, and to evaluate the possibility of using LDF analysis as a method that reflects the functional state of large resistive vessels. Wistar rats were divided into two groups: animals of the NE-group (n = 15) had 5/6 of the mass of kidney tissue removed, control animals of the SO-group (n = 15) underwent a sham operation. After 8 weeks, the reactivity of rat skin microvessels to acetylcholine (ACh) and sodium nitroprusside (NP) iontophoresis was assessed. A week later, in rats, the effect of NE on the reactivity of mesenteric arteries preconstricted with phenylephrine was evaluated in vivo using microphotographic and video recording of the diameter. It has been shown that NE does not affect the average value of perfusion in the skin of rats at rest, however, it changes the structure of the frequency range of the spectrum of fluctuations in the MCR index, increasing the value of endothelial, neurogenic, and myogenic tone. NE led to the development of endothelial dysfunction of the mesenteric arteries and MCR vessels of the skin, which was expressed in a decrease in vascular reactivity to the action of endothelium-dependent (ACh) and endothelium-independent (NP) vasodilators. Thus, the development of experimental kidney dysfunction led to changes in the spectral components of fluctuations in the MCR index in the skin, indicating an increase in tonic effects of various genesis on the vessels. NE was accompanied by a decrease in the reactivity of microvessels of the skin and mesenteric arteries, however, there was no correlation between an increase in the MCR index and dilatation of the mesenteric arteries under the action of vasodilator agonists.

Impact of unilateral dual-brachial arteries on endothelial-dependent and endothelial-independent vasodilation: a case study.

Our case study indicated that a bifurcated brachial artery exhibited worse vasodilatory responses relative to an intact contralateral artery.

#3145 ASSOCIATION OF ENDOTHELIAL NITRIC OXIDE SYNTHASE GENE POLYMORPHISM WITH ENDOTHELIAL DYSFUNCTION IN DIABETIC NEPHROPATHY AMONG AZERBAIJANIS

Abstract Background and Aims Vascular endothelial dysfunction resulting from impaired nitric oxide synthase (NOS) activity in the endothelial cells of blood vessels has been suggested as playing an important role in the pathogenesis of Diabetic nephropathy (DN). It regulates endothelial function and maintains endothelial-dependent vasodilation in multiple organs, including the kidney. The study was carried out to investigate the association of T-786C single nucleotide polymorphisms with the flow mediated dilation (FMD) in DN among type 2 diabetic subjects. Method 90 patients (45 male and 45 female) with diabetic nephropathy were recruited from Nephrology and Endocrinology departments of the Azerbaijan Medical University hospital. As a control group the results were compared with the findings in 100 healthy Azerbaijani individuals (50 males and 50 females). The study was approved by ethics committee and informed consent was obtained from all patients in written form. Brachial endothelial function was determined by brachial artery vasodilator response or brachial FMD in the dominant arm according to previously validated techniques. T786C polymorphism was detected using polymerase chain reaction-restriction fragment length polymorphism analysis. Results The results showed significant differences between DN group and control group regarding the genotype and allele distributions of the T786C single nucleotide polymorphisms. The CC genotype was significantly more frequent in diabetics nephropathy patients than in control group (42% vs. 8%, p = 0.01). FMD in allele homozygote T786C(TT), T786C(CC) and heterozygote T786C(CT) were respectively 13.5 ±0.16%, 12.3±0.19%,13.9 ±0,28%. In the study groups, Azerbaijani patients showed dominance of the C allele and a mutant homozygous genotype CC of the T786C gene of eNOS. Subjects with the 786C(CC) (n = 48) showed significantly reduced FMD with those with T786C (TT) (n = 7) (p = 0.021) and T786C (CT) (n = 35) (p = 0.023), whereas there was no significant difference in endothelial-independent vasodilation between these groups. Although subjects with homozygote T786C(TT), did not show significantly reduced levels of FMD. Who were carriers of the T786C allele demonstrated markedly reduced levels of FMD compared with noncarriers (p = 0.019). Conclusion The data suggest that in diabetic nephropathy, the eNOS T786C allele may be involved in endothelial dysfunction. Azerbaijani patients showed dominance of the C allele and a mutant homozygous genotype CC of the T786C gene of eNOS.

#3357 MORPHOMETRIC AND FUNCTIONAL EVALUATION OF A NON-RENAL VASCULATURE IN FEMALE AND MALE PKD/MHM (CY/+) RATS

Abstract Background and Aims Polycystic kidney disease (PKD) is a cystic genetic disorder of the kidneys. Vascular abnormalities are the most important non-cystic complications in PKD. In the present study, we evaluated aortic morphometry and vascular function in female and male PKD/Mhm (Cy/+) rats, an animal model of autosomal dominant PKD. Method Thoracic aortic rings from six month-old heterozygous PKD/Mhm (Cy/+) female (n = 10; 307±4g) and male (n = 10; 470±24g) and age-matched non-affected homozygous (+/+) Control-female (n = 9; 312±6g) and Control-male (n = 13; 460±14g) rats were used a) to evaluate both contractile/relaxation responses ex vivo using organ bath experiments and b) to study aortic morphometry assessed by hematoxylin&amp;eosin staining. Furthermore, immunohistochemistry for cleaved poly (ADP-ribose) polymerase (PARP)-1 was performed. Results Although there was no significant difference in body weight, serum creatinine levels were increased in the PKD-female and PKD-male rats compared with the respective controls (PKD-female 50.0±1.7 vs. Control-female 43.9±2.1 µmol/L; PKD-male 178.7±21.0 vs. Control-male 40.4± 1.3 µmol/L, p&amp;lt;0.05) and were found to be higher in PKD-male rats than in the PKD-females (p&amp;lt;0.0001). Compared to Control-male, PKD-male rats showed decreased maximum relaxation to acetylcholine (55±2% vs. 77±1%, p&amp;lt;0.05), indicating impaired endothelial function. Contractile responses to phenylephrine (3.0±0.1g vs. 3.4±0.1g, p&amp;lt;0.05) and high potassium (3.3±0.1g vs. 3.7±0.1g, p&amp;lt;0.05) were reduced in the PKD-male compared to Control-male. Additionally, in PKD-male aortas, the concentration-response curve to sodium nitroprusside, an endothelium-independent vasodilator, was shifted to the right compared to Control-male. Morphometrical analysis revealed that wall thickness and wall cross-sectional area normalized to body weight, and the wall:lumen area ratio were significantly higher in PKD-male aortas compared to Control-male. Additionally, PKD-male showed increased cleaved PARP-1 immunoreactivity confined to endothelial level compared to Control-male. All these parameters were unchanged in PKD-female rats compared to Control-female. Conclusion Six month-old PKD-male, not female, rats show endothelial dysfunction, impaired smooth muscle contraction and relaxation, pathological changes in aortic morphometry, and apoptosis in a non-renal vasculature. The rat model of autosomal dominant PKD in males can be used to identify novel targets for the treatment of this disease.

#4063 APELIN INCREASES FOREARM BLOOD FLOW IN CHRONIC KIDNEY DISEASE

Abstract Background and Aims Chronic kidney disease (CKD) affects 1 in 10 people and cardiovascular disease is its commonest complication. Despite current standard of care, many patients continue to progress to kidney failure and/or die of cardiovascular disease. Thus, there is an urgent unmet need for new treatments that slow kidney function decline and offer broad cardiovascular protection. The apelin system, comprising the apelin receptor and its two endogenous ligands apelin and elabela, is an attractive therapeutic target for CKD. Apelin is an endothelium-dependent vasodilator and a potent inotrope. Clinical studies show that apelin improves endothelial function in health and heart failure, and pre-clinical studies in models of kidney disease find apelin offers renoprotection. At present, apelin has not been studied in patients with CKD. The aims of this study were to examine the local vascular actions of apelin in CKD. Method Participants with stable, non-diabetic CKD and age- and sex-matched healthy volunteers were recruited to a prospective, randomised, placebo-controlled study. Blood pressure and arterial stiffness (measured using pulse wave velocity) were assessed at baseline. Endothelial function was examined using gold-standard venous occlusion plethysmography. Forearm vasodilatation was measured in response to incremental intra-arterial doses of acetylcholine (7.5, 15 and 30 μg/min, used to assess endothelium-dependent vasodilatation), sodium nitroprusside (1, 2 and 4 μg/min, used to assess endothelium-independent vasodilatation), and pyroglutamated apelin-13 ([Pyr1]apelin-13; 0.3, 1, 3, 10, 30 and 100 nmol/min). Circulating tissue plasminogen activator (tPA) and plasminogen activator inhibitor-1 (PAI-1) were assessed as measures of endogenous fibrinolysis. Results Fifteen patients with CKD (mean age 55±4 years; 53% male) and 15 healthy volunteers (mean age 51±3 years; 67% male) completed the study. In comparison to healthy volunteers, patients with CKD had a higher blood pressure (mean arterial pressure: 102 mmHg versus 93 mmHg, p&amp;lt;0.05) and increased pulse wave velocity (7.5±2.2 m/s versus 6.0±0.9 m/s, p&amp;lt;0.01). Similar dose-dependent vasodilatation to acetylcholine and sodium nitroprusside was seen in both groups. [Pyr1]apelin-13 increased forearm blood flow by a maximum of ∼30% in both health and CKD (p&amp;lt;0.01 compared to baseline for both) (Figure 1). This response appeared to be dose-dependent. Net tPA antigen release increased 20-70 fold in response to [Pyr1]apelin-13 in both health and CKD, with a trend to a greater release in CKD. There was no change in PAI-1. No relationship was seen between the response to [Pyr1]apelin-13 and kidney function. Conclusion Apelin promotes vasodilatation in optimally managed patients with CKD and may regulate endogenous fibrinolysis. If this effect were maintained in the long-term with systemic apelin treatment, it would be expected to reduce cardiovascular risk. Systemic studies are now justified to investigate the haemodynamic and renal effects of apelin in these patients.

#6650 SGLT2-INHIBITION IMPROVES VASCULAR FUNCTION IN TYPE 2 DIABETES: A DOUBLE BLIND, RANDOMIZED, PLACEBO CONTROLLED CROSSOVER TRIAL

Abstract Background and Aims Sodium glucose cotransporter 2 inhibitors (SGLT2i) reduce cardiovascular events and protects kidney function in type 2 diabetes (DM2) patients. These benefits may partly be related to improvement of vascular function. In this study we examined the effects of SGLT2i treatment on vasodilatory capacity in patients with DM2. Method Using a double-blind, randomized, placebo-controlled cross-over study design, we included 15 patients with DM2 and preserved kidney function (eGFR &amp;gt; 60 ml/min/1.73 m2). Each participant received four weeks of SGLT2i treatment (empagliflozin 10 mg once daily) or matching placebo. After a two-week wash-out period, each participant was crossed over to four weeks of the opposite treatment. At the end of each treatment period, vascular function was evaluated by venous occlusion plethysmography. Forearm blood flow (FBF) was measured during intra-arterial infusion of increasing concentrations of acetylcholine (ACh) and sodium nitroprusside (SNP), assessing endothelium-dependent and independent vasodilation, respectively. Repeated measures two-way ANOVA was performed to compare absolute FBF between groups. Results 11/15 (73%) of participants were male. Mean age was 68±9 (SD) years (range 49-82), eGFR was 81±10 ml/min/1.73 m2 and duration of diabetes was 15.8±9 years. 11/15 (73%) had hypertension and 9/15 (60%) received treatment with an ACE-inhibitor or Angiotensin-II blocker. 4/15 (27%) had cardiovascular disease. The median albumin-to-creatinine ratio was 29 mg/g (range: 4-1293). Both ACh and SNP dose-dependently increased FBF (Figure 1 and 2). FBF during SNP infusion was significantly higher during empagliflozin treatment as compared to placebo (p = 0.004), whereas there was no difference between empagliflozin and placebo in FBF during ACh infusion (P = 0.399). Conclusion Empagliflozin improves endothelium-independent vasodilatation in patients with DM2, whereas no changes could be observed in endothelium-dependent vasodilation. These results suggest that SGLT2i positively affects vascular function and that the effect is not related to nitric oxide from the endothelium.

Skeletal muscle microcirculatory and mitochondrial function in patients with claudication and critical limb ischemia

Introduction: Peripheral artery disease (PAD) is an atherosclerotic progressive disorder that impairs blood flow to the lower extremities. Early-stage patients often present with intermittent claudication (leg pain during walking, CLD), but as the disease progresses, patients can experience pain at rest and tissue death (critical limb ischemia, CLI). We recently reported that skeletal muscle microvascular endothelial dysfunction presented in claudicating patients with PAD. However, it is unknown if this microvascular dysfunction continues to progress with disease severity. Objective: To compare a direct investigation of the skeletal muscle microcirculation and the mitochondrial respiratory environment in patients with claudication and patients with CLI. Hypothesis: We hypothesize that (1) CLI will have greater attenuation in microcirculatory endothelial-dependent and endothelial-independent vasodilatory function (smooth muscle function) than CLD and (2) impairments in skeletal muscle microcirculatory vasodilatory function will contribute to attenuated mitochondrial respiratory function in CLD and CLI. Methods: Medial gastrocnemius muscles were harvested from PAD patients with CLD ( n = 5), CLI ( n = 6), and age-matched controls ( n = 6) by both muscle biopsies and open incisions. Arterioles were isolated to assess endothelium-dependent and independent vasodilatory responses to flow (30 mL·min -1 ), acetylcholine (ACh), and sodium nitroprusside (SNP). Skeletal muscle mitochondrial respiratory function was determined by high-resolution respirometry. Results: Endothelium-dependent vasodilation was attenuated ( P &lt; 0.05) in response to flow (CON: 53.6 ± 23%, PAD: 26.7 ± 10.4%, CLI: 20.1 ± 14.5%) and ACh (10 -3 M, CON: 64 ± 6.9%, PAD: 39.1 ± 6.7%, CLI: 20.1 ± 14.5%) in both PAD and CLI compared to CON. However, endothelium-independent vasodilation with SNP was not different in any condition ( P &gt; 0.05). Complex I+II state 3 mitochondrial respiration was blunted in both CLD and CLI compared to CON ( P &lt; 0.05). However, state 4 respiration in CON was greater than CLI ( P &lt; 0.05) but lower than CLD. Additionally, complex I+II state 3 respiration was positively associated with both flow ( r = 0.5, P = 0.01) and ACh mediated vasodilation ( r = 0.6, P = 0.009). No differences were found between CLD and CLI conditions. Conclusions: This was the first the first study to directly examine and compare skeletal muscle microvascular function in PAD patients with CLD and CLI. Our initial data indicate that functional characteristics of the skeletal muscle microvasculature and mitochondria are altered in PAD and deteriorate with disease progression. There is a correlation between alterations in the endothelium-dependent microvessel function and the dysfunction of mitochondria in the ischemic muscle raising the possibility that the microvascular dysfunction in PAD is produced by defects in the mitochondria of the microvascular endothelium. National Institutes of Health (R01 AG034995, R01 AG049868) NIH National Institute of General Medical Sciences, which funds the Great Plains IdeA-CTR Network (U54 GM115458) 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.

The effects of standard and soy-free chow on cerebral artery function in ovariectomized female mice

As females age, they transition through menopause, experiencing a decrease in estrogen and an increase in cardiovascular and neurodegenerative disease risk. When studying the effects of menopause in mice, modeled by ovariectomy, it is important to consider the effects of diet. Most standard rodent chows contain phytoestrogen-rich soybean meal, which can mimic the effects of estrogen. Understanding the impact of this soybean meal on outcomes is crucial to proper experimental design. Thus, the aim of this study was to compare the effects of standard and soy-free chows on cerebral artery endothelial function and cognitive function. We studied young female C57Bl/6J mice (n=43; ~6 months) divided into three groups: sham-controls on a soy-free diet (sham-SF), ovariectomized on a soy-free diet (OVX-SF), or OVX on a standard chow diet (OVX-SC). We assessed endothelium-dependent and -independent vasodilation in isolated pressurized posterior cerebral arteries (PCAs). We measured gene expression in cerebral arteries by real-time PCR. To assess behavioral function, we measured instinctual behavior via nest building. Data are presented as mean±SD. Compared with sham-SF, OVX-SF mice had impaired PCA endothelium-dependent vasodilation as evidenced by a maximal response that was 21% lower to acetylcholine (ACh, 60±14% vs. 47±14%, p=0.002) and 27% lower to insulin (52±17% vs. 38±8%, p=0.005). OVX-SC mice had a 27% greater PCA maximal vasodilation to insulin compared with OVX-SF mice (52±11% vs. 38±8%, p=0.001). The PCA responses to ACh and insulin did not differ between sham-SF and OVX-SC (p&gt;0.05). Additionally, the PCA response to ACh and insulin in the presence of nitric oxide synthase inhibitor L-NAME did not differ between groups (p&gt;0.05). Endothelium-independent vasodilation, measured as the PCA response to sodium nitroprusside, also did not differ between groups (p&gt;0.05). There was a trend for lower gene expression of superoxide dismutase 2 ( Sod2) in cerebral arteries from OVX-SF mice (0.7±0.2 AU) compared with OVX-SC (1.0±0.4 AU, p=0.14) but this difference did not reach statistical significance. Cerebral artery gene expression was not different between groups for Esr1 (estrogen receptor α), Insr (insulin receptor), Slca2 (GLUT1), Sod1, or Sod3 (all p&gt;0.05). Lastly, nest building scores were higher in the OVX-SC (4.3±0.5 AU) compared with sham-SF (3.2±1.2 AU, p=0.02) and OVX-SF (3.2±1.0 AU, p=0.04) mice. In summary, we found that ovariectomy impairs endothelial function in cerebral arteries by reducing nitric oxide bioavailability, but a diet containing soy mitigates these effects of ovariectomy. In addition, a diet containing soy leads to better instinctual nest-building behavior in mice. These findings highlight the importance of considering dietary soy when performing vascular and behavior tests in mice, particularly when interested in the effects of sex hormones. Luvaas Family Fund 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.

Plasma corticosterone rhythmicity loss dysregulates the renal artery circadian transcriptome and abolishes daily vasodilation variation

Molecular clocks control a daily transcriptional schedule that maintains tissue homeostasis. Glucocorticoids synchronize peripheral clocks with the master clock in the suprachiasmatic nucleus in response to ambient light. In humans and mice, arrhythmic glucocorticoids induce non-dipping blood pressure and vascular dysfunction. The mechanisms of this are poorly understood. We hypothesize that arrhythmic activation of the glucocorticoid receptor desynchronizes the molecular clock mechanism in the renal artery, a major component of blood pressure control, dysregulating normal function. Our aim was to dissect renal artery circadian physiology transcriptionally and functionally and interrogate the effect of arrhythmic glucocorticoids. Male mice, kept on a 12:12 light:dark cycle, were anesthetised with 4% isolflurane and implanted with a hypodermal pellet containing either vehicle or corticosterone (≈3.7 mg/kg per day), to flatten the endogenous glucocorticoid rhythm. After 7 days, mice were culled by cervical dislocation at 2hr intervals for 48 hours and the renal arteries taken. The renal artery circadian transcriptome was profiled using Illumina Truseq Stranded RNA-sequencing. Cosinor regression (Limorhyde) was applied to the control group and identified 465 of 14425 (~3%) protein coding transcripts with rhythmic expression (p&lt;0.005 for fit to a cosinor waveform). Of these, 265 (62%) lost their rhythm in the corticosterone-treated group. These arrhythmic transcripts were interrogated by gene set enrichment analysis (Biological Process, FDR&lt;0.05) and enriched gene sets were related to “Circadian Rhythm,” “Transforming growth factor beta” and “Smooth muscle proliferation.” Paradoxically, 919 transcripts gained de novo rhythmicity in the corticosterone group and were related to mitochondrial respiration and ATP synthesis. In parallel, we used wire myography to determine the diurnal variation in endothelium-independent vasodilation via sodium nitroprusside dose response. Renal arteries were taken from corticosterone and vehicle treated mice as described above, either during the active phase (subjective night) or inactive phase (subjective day). Data are mean ± SD and analysed by 2-way ANOVA. Vasodilation was higher during the night compared to the day in the control group, (night logEC50 =8.5±0.4 versus day logEC50 =7.5±0.4 p=0.01, n=12). In the corticosterone treated group circadian variability in vasodilation was blunted (night logEC50 =7.7±0.9 versus day logEC50=7.7±0.4, p=0.9, n=12). We speculate that temporal misalignment of the vascular molecular circadian machinery and the subsequent temporal changes in gene expression may have a direct effect on dilatory capacity. This novel study extends our understanding of circadian vascular physiology, undelining the impact of glucocorticoids on temporal gene expression.This may be clinically relevant in the pathogenesis of vascular dysfunction linked to elevated glucocorticoids in metabolic syndrome. This study was funded by the British Heart Foundation (PhD studentship code: FS/18/57/34178) and the Kidney Research UK (Intermediate Grant Code: INT_001_20181115 and IN_002_2021 0729). Analyses were carried out by Edinburgh Genomics at the University of Edinburgh. Edinburgh Genomics is partly supported through core grants from NERC (R8/H10/56), MRC (MR/K001744/1) and BBSRC (BB/J004243/1). 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.

Zanamivir infusion improves endothelial function and reduces arterial stiffness in diabetic mice

Endothelial dysfunction and arterial stiffening are consistently manifested in type 2 diabetes (T2D) and contribute to the development of cardiovascular disease. Consequently, there is an urgent need to identify novel therapies that improve endothelial function and reduce arterial stiffness in T2D. Endothelial dysfunction is characterized by a reduced capacity of the endothelium to induce vasodilation. Physiologically, this is evident as an impairment in flow-mediated dilation, a process in which the endothelial glycocalyx participates in the mechanosensation and mechanotransduction of shear that leads to the production of the vasodilator nitric oxide. Nitric oxide, in turn, has also been shown to be a potent regulator of vascular wall homeostasis, including arterial stiffness. In T2D, circulating neuraminidase activity is increased and implicated in glycocalyx degradation and endothelial dysfunction. Accordingly, we hypothesized that inhibition of neuraminidase activity would enhance endothelial function and reduce arterial stiffness in T2D. We tested this hypothesis in diabetic db/db mice infused with zanamivir (n=10) or vehicle control (n=10) for 4 weeks via subcutaneously implanted osmotic mini pumps. We chose to use the FDA approved neuraminidase inhibitor zanamivir to increase the translatability of our study. Treatment with zanamivir did not affect body weight or blood pressure. Nonetheless, it improved flow-mediated dilation in isolated mesenteric arteries assessed using pressure myography, with no associated changes in endothelium-independent vasodilation. Zanamivir also reduced stiffness in isolated mesenteric and femoral arteries, as well as aortic stiffness as assessed in vivo via pulse wave velocity and ex vivo via atomic force microscopy. These results indicate that zanamivir is a potential therapeutic to ameliorate vascular dysfunction in T2D. National Institutes of Health grant: R01HL153264 to LM-L and JP 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.