管理Rho激酶介导的钙敏 - 羟色胺对诱发大鼠脑动脉压力依赖性血管收缩的作用。.docVIP

Pressure-dependent contribution of Rho kinase-mediated calcium sensitization in serotonin-evoked vasoconstriction of rat cerebral arteries Ahmed F El-Yazbi,1 Rosalyn P Johnson,1 Emma J Walsh,1 Kosuke Takeya,2 Michael P Walsh,2 and William C Cole1 1Physiology Pharmacology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1 2Biochemistry Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 4N1 Corresponding authorW. C. Cole: The Smooth Muscle Research Group, Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, 3330 Hospital Drive N.W., Calgary, Alberta, Canada T2N 4N1. Email: wcole@ucalgary.ca Received January 7, 2010; Accepted March 24, 2010. Abstract Our understanding of the cellular signalling mechanisms contributing to agonist-induced constriction is almost exclusively based on the study of conduit arteries. Resistance arteries/arterioles have received less attention as standard biochemical approaches lack the necessary sensitivity to permit quantification of phosphoprotein levels in these small vessels. Here, we have employed a novel, highly sensitive Western blotting method to assess: (1) the contribution of Ca2+ sensitization mediated by phosphorylation of myosin light chain phosphatase targeting subunit 1 (MYPT1) and the 17 kDa PKC-potentiated protein phosphatase 1 inhibitor protein (CPI-17) to serotonin (5-HT)-induced constriction of rat middle cerebral arteries, and (2) whether there is any interplay between pressure-induced myogenic and agonist-induced mechanisms of vasoconstriction. Arterial diameter and levels of MYPT1 (T697 and T855), CPI-17 and 20 kDa myosin light chain subunit (LC20) phosphorylation were determined following treatment with 5-HT (1 μmol l?1) at 10 or 60 mmHg in the absence and presence of H1152 or GF109203X to suppress the activity of Rho-associated kinase (ROK) and protein kinase C (PKC), respectively. Although H1152 and GF109203X supp