Potassium channels and membrane potential in the modulation of intracellular calcium in vascular endothelial cells
The endothelium plays a vital role in the control of vascular functions, including modulation of tone; permeability and barrier properties; platelet adhesion and aggregation; and secretion of paracrine factors. Critical signaling events in many of these functions involve an increase in intracellular free Ca2+ concentration ([Ca2+]i). This rise in [Ca2+]i occurs via an interplay between several mechanisms, including release from intracellular stores, entry from the extracellular space through store depletion and second messenger-mediated processes, and the establishment of a favorable electrochemical gradient. The focus of this review centers on the role of potassium channels and membrane potential in the creation of a favorable electrochemical gradient for Ca 2+ entry. In addition, evidence is examined for the existence of various classes of potassium channels and the possible influence of regional variation in expression and experimental conditions.