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

蛋白酶激活受体（PARs）介导多种细胞类型对各种蛋白酶的细胞反应，包括平滑肌和血管内皮。PARs还可能在组织/器官的微循环中发挥重要作用。研究了PARs刺激是否会引起小动脉平滑肌细胞的反应；特别提到PARs刺激期间细胞内Ca^<2+>([Ca^(2+)]i)动力学和一氧化氮（NO）的产生，因为[Ca^(2+)]i和NO都是维持血管张力的关键因素。这些是通过实时共聚焦显微镜测量的。取大鼠脑和睾丸小动脉。凝血酶和par1激活肽（AP）诱导脑小动脉（直径< 50 μm）平滑肌细胞[Ca^<2+>]i升高和收缩。对PAR1激活的反应是由细胞内Ca^<2+>储存的Ca^<2+>动员引起的。胰蛋白酶和PAR2-AP诱导细胞中[Ca^<2+>] i的减少，这种作用可以通过内皮源性NO和/或通过促进。Ca^<2+>固存机制。PAR3-和4-AP无影响。与脑小动脉相比，[Ca^<2+>]，大（直径<100 μ）脑小动脉或睾丸小动脉的平滑肌细胞的动力学在PARs激活期间保持不变。根据[Ca^<2+>]，影像学结果、免疫组化结果显示脑小动脉平滑肌和内皮中有凝血酶受体和PAR2，大动脉中无。睾丸小动脉中PARs的免疫反应性较弱。这是第一个证明PARs激活对平滑肌[Ca^<2+>]I动力学和脑小动脉收缩/舒张的影响的研究，暗示了蛋白酶在大脑区域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.