Activation Of K_Ca By Nitric Oxide In Resistance Vascular Smooth Muscle Cells From SHR_SP And Normatensive Rats

Introduction:Smooth muscle membrane potential appears to regulate vascular tone through opening potassium channels,with membrane hyperpolarization closing voltage-dependent calcium channels, decreasing calcium entry and intracellular calcium concentration. Kca channels in vascular smooth muscle play a key role in regulation of membrane potential for its dense distribution and large conductance, and play a negerative feedback role during the devolpment of pressure-induced myogenic tone. Nitric oxide (NO) released from the endothelium or generated by the metabolism of nilrovasdilators stimulates soluble guanylyl cyclase activity to increase synthesis of guanosine 3',5'-cyclic monophosphate (cGMP),which activates the cGMP-dependent protein kinase(PKG).Recent studies demonstrated that PKG stimulates KCa activity in myocytes from coronary,cerebral,or pulmonary arteries by phosphorylation of ion channel protein. However ,it has been reported by Bolotina that NO may modulate Kca channels of aorta artery directly without any effects on cGMP transduction.but little is known about the...