Effect of PARs on the smooth muscles of arterioles, analyzing by bioimaging method

蛋白水解酶激活受体(PARs)在多种细胞类型中介导细胞对各种蛋白水解酶的反应，包括平滑肌和血管内皮细胞。PARs也可能在组织/器官的微循环中发挥重要作用。本文探讨了刺激PARS是否会引起小动脉平滑肌细胞的反应，特别是细胞内钙离子([Ca^(2+)]i)动力学和一氧化氮(NO)的产生，因为[Ca^(2+)]i和NO都是维持血管紧张性的关键因素。用实时共聚焦显微镜进行测量。小动脉取自大鼠脑和睾丸。在大脑小动脉(直径50μm)的平滑肌细胞上，凝血酶和PAR_1激活肽(AP)可引起[Ca~(2+)]i升高和收缩。对PAR1激活的反应是由细胞内钙库中的钙动员引起的。胰酶和PAR2-AP可引起细胞内[Ca~(2+)]i降低，此作用可通过内皮源性NO和/或促进剂介导。CA^lt；2+；隔离机制。3-和4-AP对此无影响。与小脑小动脉相比，大(直径100μ)脑或睾丸小动脉的平滑肌细胞动力学在PARS激活过程中保持不变。与[Ca^&lt；2+&gt；]相一致，免疫组织化学结果显示，脑小动脉的血管内皮细胞和血管内皮细胞有凝血酶受体和凝血酶受体的表达，而较大的脑小动脉内皮细胞无凝血酶受体表达。睾丸小动脉内PARS免疫反应较弱。这是首次证实激活PARs对血管平滑肌[Ca~(2+)]i动力学和脑小动脉收缩/松弛的影响，暗示了蛋白水解酶在脑局部组织循环中的重要作用。

Protease-activated receptors (PARs) mediate cellular responses to various proteases in numerous cell types, including smooth muscles and the endothelium of blood vessels. PARs may also play important roles in microcirculation in tissue/organs. The issue of whether the stimulation of PARs induces responses in smooth muscle cells of arterioles was examined; with special reference to intracellular Ca^<2+>([Ca^(2+)]i) dynamics and nitric oxide (NO) production during PARs stimulation, since [Ca^(2+) ]i and NO are both key factors in the maintenance of strain in blood vessels. These were measured by real-time confocal microscopy. Arterioles were taken obtained from the brain and testis of rats. In smooth muscle cells of small cerebral arterioles (< 50 μm in diameter), thrombin and PAR1-activating peptide (AP) induced an increase in [Ca^<2+>]i and contraction. The response to PAR1 activation was caused by Ca^<2+>mobilization from intracellular Ca^<2+>stores. Trypsin and PAR2-AP induced a decrease in [Ca^<2+>] i in the cells, and this effect can be mediated by endothelium-derived NO and/or by promoting. Ca^<2+> sequestration mechanism. PAR3- and 4-AP had no effect. In contrast to small cerebral arterioles, [Ca^<2+>], dynamics in smooth muscle cells of large (<100 μ in diameter) cerebral or testicular arterioles remained unchanged during PARs activation. In accordance with [Ca^<2+>], imaging results, immunohistochemical results showed thrombin receptor and PAR2 in smooth muscles and endothelium of small cerebral arterioles, but not in larger those. The immunoreactivity of PARs in testicular arterioles was faint. This is the first study to demonstrate the effects of PARs activation on the [Ca^<2+>]I dynamics of smooth muscles and the contraction/relaxation of cerebral arterioles, implicating the significant role of proteases in the regional tissue circulation of the brain.