Abstract
A sheet of endothelial cells was isolated from a guinea-pig mesenteric artery and placed on a cover slip with the abluminal surface up. Two patch electrodes were applied on two adjacent endothelial cells which should be coupled electrically with gap junctions. The patch membrane was ruptured in one electrode and the membrane potential was monitored in the current clamp mode. The other electrode was used in the cell-attached patch-clamp mode and the patch membrane potential was controlled using the membrane potential recorded through the first electrode. The membrane potential was usually less negative than -10 mV and the cells seemed to have lost the intracellular K+. Incubation in a 150 mM-K+ solution for 10-15 min was employed to recover the high intracellular K+ concentration and acetylcholine (ACh, 3 μM) was applied after the normal extracellular solution was reintroduced. ACh induced a transient hyperpolarization and openings of 2 pS channels. The channel had a reversal potential of -70 mV and did not open in the presence of apamin (100 nM). This channel was distinct from the nonselective cation channels which were also activated by ACh, and seemed to be the K+ channel responsible to the ACh-induced hyperpolarization. [Jpn J Physiol 54 Suppl:S131 (2004)]
