The Calcium Signaling Mechanisms in Arterial Smooth Muscle and Endothelial Cells.

The contractile state of resistance arteries and arterioles is a crucial determinant of blood pressure and blood flow. Physiological regulation of arterial contractility requires constant communication between endothelial and smooth muscle cells. Various Ca signals and Ca -sensitive targets ensure dynamic control of intercellular communications in the vascular wall. The functional effect of a Ca signal on arterial contractility depends on the type of Ca -sensitive target engaged by that signal. Recent studies using advanced imaging methods have identified the spatiotemporal signatures of individual Ca signals that control arterial and arteriolar contractility. Broadly speaking, intracellular Ca is increased by ion channels and transporters on the plasma membrane and endoplasmic reticular membrane. Physiological roles for many vascular Ca signals have already been confirmed, while further investigation is needed for other Ca signals. This article focuses on endothelial and smooth muscle Ca signaling mechanisms in resistance arteries and arterioles. We discuss the Ca entry pathways at the plasma membrane, Ca release signals from the intracellular stores, the functional and physiological relevance of Ca signals, and their regulatory mechanisms. Finally, we describe the contribution of abnormal endothelial and smooth muscle Ca signals to the pathogenesis of vascular disorders. © 2021 American Physiological Society. Compr Physiol 11:1831-1869, 2021.