Endothelial ion channels and their functions [Endoteldeki· i·yon kanallari ve i·şlevleri·]

Endothelium produces endothelium-drived relaxing factor (EDRF), now widely accepted to be nitric oxide (NO), prostacyclin (PGIi), endothelium-derived hyperpolarizing factor (EDHF), endothelin, ATP and molecules Involved In cell proliferation. Endothelial cells (ECs) are classed as nonexcitable cells because they do not generate action potential. Ionic channels in vascular endothelium play significant roles, controlling resting potential, signal transduction and stimulus-secretion coupling. In a general sense, in both smooth muscle cells and ECs, the activities of ion channels are present and the resultant membrane potential of these cell determine the blood flow. Channel currents in ECS are influenced by released vasoactive factors, mechanical forces such as blood flow and pressure, and metabolic conditions. To date, most electrophysiological data have been obtained from large vessel ECs, often in culture. Resting potential in culture isolated EC s recorded with microelectrodes are -40 to -60 mV. The surface area of ECs is between 1000-2000 µ2, membrane capacity (Cm) 1 µF/cm2 and cell capacity (10-50 pF)