Reduced Endothelial Leptin Signaling Increases Vascular Adrenergic Reactivity in a Mouse Model of Congenital Generalized Lipodystrophy

The adipokine leptin, which is best-known for its role in the control of metabolic function, is also a master regulator of cardiovascular function. While leptin has been approved for the treatment of metabolic disorders in patients with congenital generalized lipodystrophy (CGL), the effects of chronic leptin deficiency and the treatment on vascular contractility remain unknown. Herein, we investigated the effects of leptin deficiency and treatment (0.3 mg/day/7 days) on aortic contractility in male Berardinelli-Seip 2 gene deficient mice (gBscl2-/-, model of CGL) and their wild-type control (gBscl2+/+), as well as in mice with selective deficiency in endothelial leptin receptor (LepREC-/-). Lipodystrophy selectively increased vascular adrenergic contractility via NO-independent mechanisms and induced hypertrophic vascular remodeling. Leptin treatment and Nox1 inhibition blunted adrenergic hypercontractility in gBscl2-/- mice, however, leptin failed to rescue vascular media thickness. Selective deficiency in endothelial leptin receptor did not alter baseline adrenergic contractility but abolished leptin-mediated reduction in adrenergic contractility, supporting the contribution of endothelium-dependent mechanisms. These data reveal a new direct role for endothelial leptin receptors in the control of vascular contractility and homeostasis, and present leptin as a safe therapy for the treatment of vascular disease in CGL.

ZnO Nanoparticles Induce Dyslipidemia and Atherosclerotic Lesions Leading to Changes in Vascular Contractility and Cannabinoid Receptors Expression as Well as Increased Blood Pressure

ZnO nanoparticles (ZnONPs) have been shown to have therapeutic potential in some diseases such as diabetes and cancer. However, concentration-dependent adverse effects have also been reported. Studies which evaluate the effects of ZnONPs on the cardiovascular system are scarce. This study aimed to evaluate the cardiovascular effects of a low dose of ZnONPs administered chronically in healthy rats. Changes in dyslipidemia biomarkers, blood pressure, aortic wall structure, vascular contractility, and expression of cannabinoid receptors in the aorta wall were evaluated. Healthy rats were divided into two groups: control or treated (one, two, and three months). The treated rats received an oral dose of 10 mg/kg/day. The results showed that treatment with ZnONPs induced dyslipidemia from the first month, increasing atherosclerosis risk, which was confirmed by presence of atherosclerotic alterations revealed by aorta histological analysis. In in vitro assays, ZnONPs modified the aorta contractile activity in response to the activation of cannabinoid receptors (CB1 and CB2). The expression of CB1 and CB2 was modified as well. Moreover, ZnONPs elicited an increase in blood pressure. In conclusion, long-time oral administration of ZnONPs induce dyslipidemia and atherosclerosis eliciting alterations in aorta contractility, CB1 and CB2 receptors expression, and an increase in blood pressure in healthy rats.

Abstract 37: Loss Of BK Ca - IP3R Functional Coupling Underlies Vascular Hypercontractility In Spontaneously Hypertensive Rats

The cellular mechanisms underlying enhanced vascular contractility in hypertension are still not fully clear. Recent studies have demonstrated that functional coupling between the large-conductance Ca 2+ -activated K + (BK Ca ) channel in the cell membrane and inositol 1,4,5-trisphosphate receptor (IP3R) in the endoplasmic reticulum is involved in the regulation of intracellular Ca 2+ in vascular smooth muscle cells (VSMC) and vascular contractility. Here, we examined the role of BK Ca -IP3R coupling in vascular hypercontractility in Spontaneously Hypertensive Rats (SHR), as compared with Sprague Dawley (SD) rats. In pressurized mesenteric arteries, paxilline (1μM), a selective BK Ca channel blocker, significantly increased norepinephrine (1μM)-induced vasoconstriction in both SHR (% initial diameter: 71.6±6.8% [95.9±13 of 132.8±6.2 μm] and 65.0±4.8% [80.6±7.7 of 123.6±3.9 μm] in arteries treated with vehicle and paxilline respectively, n=4, P<0.05) and in SD rats (% initial diameter: 84.2±7.9% [108.4±12.3 of 128.5±2.5 μm] and 60.5±0.2% [77.4±0.7 of 127.9±0.6 μm] in arteries treated with vehicle and paxilline respectively, n=3, P<0.05). Paxilline-induced increases in vasoconstriction were significantly greater in arteries of SD as compared with SHR rats, suggesting that BK Ca channels are involved in hypercontractility in SHR. In inside-out patch-clamp, BK Ca channels in VSMCs isolated from mesenteric arteries of SHR and SD rats displayed identical calcium and voltage sensitivity. We next examined the effect of the selective IP3R-agonist, Adenophostin A, on BK Ca current density in VSMCs, using patch-clamp whole-cell mode. The results demonstrated that Adenophostin A (5μM) significantly increased BK Ca current density in VSMCs from both SHR (from 41.9± 5.7 to 61.5±9.1 pA/pF; n=6 cells, p<0.05) and SD rats (from 29.9 ± 8.0 to 92.6 ± 9.1 pA/pF, n=5 cells, P<0.01). There was no significant difference in basal BKca current density between SHR and SD rats; however, the Adenophostin-induced elevation in BK Ca current density was significantly diminished in VSMCs of SHR as compared with SD rats. In conclusion, the results indicate that loss of functional coupling between BKca and IP3R is involved in vascular hypercontractility in SHR arteries.

Hyperhomocysteinemia enhances the negative influence of Salmonella typhimurium LPS on vascular contractility and gene expression of receptor and regulatory proteins in rats

Наиболее тяжелым проявлением SARS-CoV-2 инфекции является развитие острого респираторного дистресс-синдрома. Высокий уровень гомоцистеина в крови пациентов - прогностически неблагоприятный фактор течения COVID-19 инфекции. Также развитие полиорганной недостаточности при COVID-19 инфекции часто утяжеляется эндотоксемией. Цель исследования. Изучение влияния гипергомоцистеинемии и липополисахарида (ЛПС) Salmonella Typhimurium на сократимость аорты и почечной артерии крыс и экспрессию генов рецепторных и регуляторных белков. Методикы. Моделирование гипергомоцистеинемии проводили путем добавления в воду L-метионина в концентрации 5 г/л (0,5%) в течение 14 дней. Эндотоксемию вызывали введением ЛПС Salmonella Typhimurium (Sigma, 5 мг/кг, в/б). Силу сокращения изолированных сосудов измеряли в изометрическом режиме. Экспрессию генов оценивали при помощи ПЦР-анализа. Результаты. Установлено, что через 24 часа после однократного введения животным ЛПС сила сокращения аорты возрастает в ответ на воздействие ангиотензина II (ATII, в 1,6 раза), аргнинвазопрессина (AVP, в 1,5 раза), и снижается после введения эндтелина-1 (ET-1, в 1,6 раза), по сравнению с аналогичными показателями контрольных крыс. При повторном введении ЛПС сосуды теряют чувствительность к вазоконстрикторам. У крыс после метиониновой нагрузки в плазме крови более чем в 3 раза повышается уровень общего гомоцистеина. Гомоцистеинемия приводит к выраженным нарушениям нейроэндокринной регуляции сократимости сосудов: снижается чувствительность аорты и почечной артерии к вазоконстрикторному действию ATII (в 1,7 и 2,6 раза соответственно), AVP (в 1,5 и 1,7 раза), серотонина (5HT, в 1,2 и 1,8 раза) и ET1 (в 1,5 и 1,6 раза). Установлено, что введение ЛПС крысам на фоне высокого уровня гомоцистеина в плазме ещё в большей степени усиливает выявленные нарушения сократительной активности сосудов. У крыс после введения ЛПС выявлен низкий уровень экспрессии вазоконстрикторных адренорецепторов α1A-AR, α1D-AR и вазодилататорных β1- и β2-адренорецепторов и высокий - ETA и ETB рецепторов. Как ЛПС, так и гипергомоцистеинемия приводят к значительному снижению содержания мРНК ангиотензинпревращающих ферментов ACE, ACE2 и рецепторов MasR, V1AR. У крыс после метиониновой нагрузки выявлено снижение экспрессии генов инозитолтрисфосфатных рецепторов IP3R2, IP3R3, что свидетельствует о нарушении кальциевого гомеостаза в сосудах. Метиониновая нагрузка не приводила к летальным исходам. В группе животных после однократного введения ЛПС смертность составляла 7%, а в группе с введением ЛПС после метиониновой нагрузки - 50%. Заключение. Таким образом, гипергомоцистеинемия усиливает ЛПС-индуцированные нарушения нейроэндокринной регуляции тонуса сосудов, отягощает течение и увеличивает смертность при эндотоксемии. The most severe manifestation of SARS-CoV-2 infection is the development of acute respiratory distress syndrome. A high blood level of homocysteine in patients is a prognostically unfavorable factor for the course of COVID-19 infection. The development of multiple organ failure in COVID-19 infection is aggravated by endotoxemia. The aim of the study was to investigate the effect of hyperhomocysteinemia and Salmonella Typhimurium lipopolysaccharide (LPS) on the rat aorta and renal artery contractility and the gene expression of receptor and regulatory proteins. Methods. Hyperhomocysteinemia was modeled in rats by adding L-methionine to drinking water at a concentration of 5 g/L (0.5%) for 14 days. Endotoxemia was induced with a single injection of Salmonella Typhimurium LPS (Sigma, 5 mg/kg, intraperitoneally). The contractile force of isolated blood vessels was measured in the isometric mode. Gene expression was assessed with the PCR analysis. Results. At 24 h after a single injection of LPS, the force of aortic contractile response to angiotensin II (ATII) increased 1.6 times and to arginine vasopressin (AVP) 1.5 times whereas the response to endothelin-1 (ET1) decreased by 37.5% compared to the respective values for control rats. Upon repeated administration of LPS, the blood vessels lost the sensitivity to vasoconstrictors. After methionine loading, the plasma level of total homocysteine increased more than three times. Homocysteinemia resulted in severe disorders in the neuroendocrine regulation of vascular contractility, including decreased sensitivity of the aorta and the renal artery to vasoconstrictor effects of ATII (41.2% and 61.5%, respectively), AVP (33.3% and 41.2%, respectively), serotonin (5HT, 16.7% and 44.4%, respectively) and ET1 (33.3% and 37.5%, respectively). The administration of LPS to rats on the background of a high plasma level of homocysteine further aggravated the disorders of vascular contractile activity. Administration of LPS was associated with lower expression of vasoconstrictor α1A- and α1D-adrenoceptors, and of vasodilator β1- and β2-adrenoceptors and with a higher expression of ETA and ETB receptors. Both LPS and hyperhomocysteinemia led to significant decreases in angiotensin-converting enzymes ACE and ACE2 mRNA, and in MasR and V1AR receptor mRNA. The methionine loading induced a decrease in the gene expression of inositol trisphosphate receptors IP3R2 and IP3R3, which indicated a disorder of calcium homeostasis in the blood vessels. The methionine loading was not fatal. In the group of animals after a single administration of LPS, the mortality rate was 7%, and in the group after the administration of LPS and methionine loading, the mortality rate was 50%. Conclusion. Thus, hyperhomocysteinemia enhances LPS-induced disorders in the neuroendocrine regulation of vascular tone, aggravates the course of endotoxemia, and increases the mortality rate.

L-Arginine reduces downstream vascular contractility after flow-diverting device deployment: A preliminary study in a rabbit model

Background Flow diverters (FDs) are an effective treatment for intracranial aneurysms, though not free from hemorrhagic complications. A previous study demonstrated increased vascular contractility after FD-implantation as a potential mechanism of distal complications. Our study aimed to investigate whether L-arginine medication affects vascular contractility following FD deployment in a rabbit model. Methods FDs were implanted in the aorta of normal rabbits (+FD, n = 10), with sham-operated aorta as controls (n = 5). L-Arginine was given in the drinking water (2.25% L-arginine hydrochloride) of half of the +FD animals (+FD/+Arg). Force contraction vascular contractility studies were performed on the aortic rings proximal and distal to the FD using an organ bath. Total eNOS, eNOS(pS1177), eNOS(pT495), COX-2, and S100A4 were quantified by western analysis on total protein lysates from aortic segments, normalizing to GAPDH. Results Mean vascular contractility was 53% higher in distal relative to proximal aortic segments (P = 0.0038) in +FD animals, but were not significantly different in +FD/+Arg animals, or in sham-operated controls. The +FD animals expressed significantly reduced levels of eNOS(pS1177) than sham-operated controls (P = 0.0335), while both the +FD and +FD/+Arg groups had reduced levels of eNOS(pT495) relative to sham-operated controls (P = 0.0331 and P = 0.0311, respectively). Conclusion These results suggest that L-arginine medication reduces distal vascular contractility after FD treatment via nitric oxide production and thus might mitigate risk for downstream complications.

Type 2 diabetes progression differently affects endothelial function and vascular contractility in the aorta and the pulmonary artery

Type 2 diabetes (T2D) is associated with cardiovascular and pulmonary disease. How T2D affects pulmonary endothelial function is not well characterized. We investigated the effects of T2D progression on contractility machinery and endothelial function in the pulmonary and systemic circulation and the mechanisms promoting the dysfunction, using pulmonary artery (PA) and aorta. A high-fat (HF, 3 weeks 60% lipid-rich diet) and a high-fat/high-sucrose (HFHSu, combined 60% lipid-rich diet and 35% sucrose during 25 weeks) groups were used as prediabetes and T2D rat models. We found that T2D progression differently affects endothelial function and vascular contractility in the aorta and PA, with the contractile machinery being altered in the PA and aorta in prediabetes and T2D animals; and endothelial function being affected in both models in the aorta but only affected in the PA of T2D animals, meaning that PA is more resistant than aorta to endothelial dysfunction. Additionally, PA and systemic endothelial dysfunction in diabetic rats were associated with alterations in the nitrergic system and inflammatory pathways. PA dysfunction in T2D involves endothelial wall mineralization. The understanding of the mechanisms behind PA dysfunction in T2D can lead to significant advances in both preventative and therapeutic treatments of pulmonary disease-associated diabetes.

Dietary sodium restriction sex specifically impairs endothelial function via mineralocorticoid receptor-dependent reduction in NO bioavailability in Balb/C mice

Female sex confers improved endothelial relaxation and vascular constriction responses in female Balb/C mice compared with males under baseline conditions. Sodium restriction impairs endothelial function, which is nitric oxide dependent, and increases vascular contractility in association with reduced vascular endothelial nitric oxide synthase and NOX4 expression in female mice ablating the baseline sex difference. Mineralocorticoid receptor antagonism ablates sodium restriction-induced endothelial dysfunction, but not increased vascular contractility, in female mice.