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Abstract：
BACKGROUND: The vasoconstrictor effects of angiotensin II via type 1 angiotensin II receptors in vascular smooth muscle cells are well established, but the direct effects of angiotensin II on vascular endothelial cells (VECs) in vivo and the mechanisms how VECs may mitigate angiotensin II-mediated vasoconstriction are not fully understood. The present study aimed to explore the molecular mechanisms and pathophysiological relevance of the direct actions of angiotensin II on VECs in kidney and brain microvessels in vivo.
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.
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.
摘要：
背景：血管平滑肌细胞中血管紧张素II通过1型血管紧张素II受体的血管收缩作用已得到充分证实，但血管紧张素II在体内对血管内皮细胞(VECs)的直接作用以及VECs如何减轻血管紧张素II介导的血管收缩的机制尚不完全清楚.本研究旨在探讨血管紧张素II对体内肾脏和脑微血管中VECs的直接作用的分子机制和病理生理相关性。
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。
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。
