KCNA3 and Hypertension: They also play an important role in various pathophysiological conditions including hypertension, diabetes, ischemia and hypoxia.(43) The opening of potassium channels causes hyperpolarization of smooth muscle cells, and with this the closure of Ca2+ channels and reduction of cytosolic Ca2+, leading to relaxation and vasodilation.(44) More specifically, in the human umbilical artery, vasodilation induced by cyclic monophosphate of guanosine is mediated by the activation of potassium channels.(45)