Intercellular Electrical Communication among Rat Smooth Muscle and Endothelial Cells

Objectives: Endothelial cells collaborate with vascular smooth muscles to regulate vascular tone. We tried to evaluate intercellular electrical communication in rat vascular tissues. Methods: The first-order arterioles were dissected out open to reveal the endothelial layer. The patch clamp method was applied to both the smooth muscle and endothelial cells simultaneously in the perforated whole-cell clamp configuration to minimize the access resistance. Lucifer yellow was injected into a cell to examine the homocellular and heterocellular dye coupling between smooth muscle and endothelial cells. Results: Electrotonic potentials could conduct through myoendothelial couplings, which seemed to behave as ohmic resistors without rectification. Junctional conductance through heterocellular coupling between smooth muscle and endothelial cells was significantly smaller than that through homocellular coupling. Dye transfer between cells also showed gap junctional communication. Conclusions: the resistance of myoendothelial couplings is appreciable, the endothelium may be important as a low resistance path connecting many smooth muscle cells. This model may be useful for examining the effect of pH and Ca2+ concentration on vasomotor tone as well as exudates in the periapical tissues that is thought to be inhibited with Ca(OH)2. This study was supported by a Grant-in-Aid for Scientific Research from the Japanese Ministry of Education, Culture, Sports, Science and Technology (No. 14370614).