RESULTS: Changes in VEC intracellular calcium ([Ca2+]i) and nitric oxide (NO) production were visualized by intravital multiphoton microscopy of cadherin 5-Salsa6f mice or the endothelial uptake of NO-sensitive dye 4-amino-5-methylamino-2\',7\'-difluorofluorescein diacetate, respectively. Kidney fibrosis by unilateral ureteral obstruction and Ready-to-use adeno-associated virus expressing Mouse Renin 1 gene (Ren1-AAV) hypertension were used as disease models. Acute systemic angiotensin II injections triggered >4-fold increases in VEC [Ca2+]i in brain and kidney resistance arterioles and capillaries that were blocked by pretreatment with the type 1 angiotensin II receptor inhibitor losartan, but not by the type 2 angiotensin II receptor inhibitor PD123319. VEC responded to acute angiotensin II by increased NO production as indicated by >1.5-fold increase in 4-amino-5-methylamino-2\',7\'-difluorofluorescein diacetate fluorescence intensity. In mice with kidney fibrosis or hypertension, the angiotensin II-induced VEC [Ca2+]i and NO responses were significantly reduced, which was associated with more robust vasoconstrictions, VEC shedding, and microthrombi formation.
CONCLUSIONS: The present study directly visualized angiotensin II-induced increases in VEC [Ca2+]i and NO production that serve to counterbalance agonist-induced vasoconstriction and maintain residual organ blood flow. These direct and endothelium-specific angiotensin II effects were blunted in disease conditions and linked to endothelial dysfunction and the development of vascular pathologies.
结果:通过cadherin5-Salsa6f小鼠的活体多光子显微镜观察VEC细胞内钙([Ca2]i)和一氧化氮(NO)产生的变化或NO-敏感染料4-氨基-5-甲基氨基-2',7\'-二氟荧光素二乙酸酯,分别。单侧输尿管梗阻引起的肾脏纤维化和表达小鼠肾素1基因(Ren1-AAV)高血压的现成性腺相关病毒被用作疾病模型。急性全身性血管紧张素II注射引发脑和肾脏阻力小动脉和毛细血管中VEC[Ca2]i增加>4倍,这些小动脉和毛细血管被1型血管紧张素II受体抑制剂氯沙坦预处理阻断,但不是2型血管紧张素II受体抑制剂PD123319。VEC对急性血管紧张素II的反应是NO产生增加,4-氨基-5-甲基氨基-2增加>1.5倍,7\'-二氟荧光素二乙酸酯荧光强度。在患有肾纤维化或高血压的小鼠中,血管紧张素II诱导的VEC[Ca2+]i和NO反应显著降低,这与更强烈的血管收缩有关,VEC脱落,和微血栓形成。
结论:本研究直接观察了血管紧张素II诱导的VEC[Ca2+]i和NO产生的增加,这些增加用于抵消激动剂诱导的血管收缩并维持残余器官血流。这些直接的和内皮特异性的血管紧张素II作用在疾病条件下被减弱,并与内皮功能障碍和血管病变的发展有关。