Current injection into endothelial or smooth muscle cells demonstrated direct electrical coupling, evoking hyperpolarization with relaxation or depolarization with constriction.
Endothelial cells and smooth muscle cells in hamster feed arteries are electrically coupled, allowing electrical signals conducted along the endothelium to directly evoke vasomotor responses.
Endothelial cells (ECs) govern smooth muscle cell (SMC) tone via the release of paracrine factors (eg, NO and metabolites of arachidonic acid). We tested the hypothesis that ECs can promote SMC relaxation or contraction via direct electrical coupling. Vessels (resting diameter, 57+/-3 microm; length, 4 mm) were isolated, cannulated, and pressurized (75 mm Hg; 37 degrees C). Two microelectrodes were used to simultaneously impale 2 cells (ECs or SMCs) in the vessel wall separated by 500 microm. Impalements of one EC and one SMC (n=26) displayed equivalent membrane potentials at rest, during spontaneous oscillations, and during hyperpolarization and vasodilation to acetylcholine. Injection of -0.8 nA into an EC caused hyperpolarization ( approximately 5 mV) and relaxation of SMCs (dilation, approximately 5 microm) along the vessel segment. In a reciprocal manner, +0.8 nA caused depolarization ( approximately 2 mV) of SMCs with constriction ( approximately 2 microm). Current injection into SMCs while recording from ECs produced similar results. We conclude that ECs and SMCs are electrically coupled to each other in these vessels, such that electrical signals conducted along the endothelium can be directly transmitted to the surrounding smooth muscle to evoke vasomotor responses.
Emerson et al. (Fri,) reported a other. Current injection into endothelial or smooth muscle cells was evaluated on Membrane potential and vasomotor responses. Current injection into endothelial or smooth muscle cells demonstrated direct electrical coupling, evoking hyperpolarization with relaxation or depolarization with constriction.