KCa-channel blockade prevents sustained pressure-induced depolarization in rat mesenteric small arteries

The role of Ca2+-activated K+ (KCa) channels in pressure-induced depolarization and myogenic response in rat mesenteric small arteries was analyzed by using microelectrodes. Rat mesenteric arteries exposed to elevated transmural pressure exhibited smooth muscle depolarization and moderate myogenic responses. Administration of norepinephrine (NE) also induced vascular constriction, depolarization and oscillations in the diameter and membrane potential of the rat mesenteric small arteries. However, the effects of NE were inhibited by blockade of KCa channels.