Endothelial cell ion channel expression and function in arterioles and resistance arteries

Abstract

Ion channels importantly contribute to the function of endothelial cells. They serve as the major source of intracellular Ca 2+, which, in turn, controls the production of endothelium-derived vasodilators, the permeability of the endothelium, gene expression, and other properties of endothelial cells. In addition, the activity of ion channels determines the membrane potential of endothelial cells that serves as an important signal for cell-cell communication between endothelial cells and between endothelial cells and overlying smooth muscle cells, and may feedback to regulate the activity of the ion channels themselves. This review provides an overview of the expression and function of endothelial ion channels that contribute to Ca 2+ and membrane potential signaling that is involved in the regulation and modulation of vasomotor tone of resistance arteries and arterioles. Channels discussed include inositol 1,4,5 trisphosphate receptors that mediate agonist-induced Ca 2+ release from endoplasmic reticulum stores; members of the transient receptor potential family and other channels that mediate agonist-induced Ca 2+ infl ux through the plasma membrane; Ca 2+-activated K + channels that mediate agonist-induced membrane hyperpolarization; and inward rectifi er K + channels that serve as sensors for changes in extracellular K + and amplifi ers of hyperpolarization induced by the activity of other ion channels. It is emphasized that all of these channels exist as members of macromolecular signaling complexes providing a rich environment for regulation of their activity and the function of endothelial cells in resistance arteries and arterioles.