Ca2(+)-sensitive K+ channel in aortic smooth muscle of rats.
We measured K+ channel activity in inside-out patches of cell membrane from aortic vascular smooth muscle cultured (Passages 1-3) from Wistar, Wistar-Kyoto, and spontaneously hypertensive rats (SHR). With [Ca2+]i between 25 and 100 nm and 150 mm K+ on both sides of the membrane, the conductance of this channel was 55 +/- 7 pS (slope of current-voltage curve through 0 mV) and the current was outwardly rectified. There was no difference in single-channel conductance among the three rat strains. Increasing negative holding voltages or increasing [Ca2+]i, increased the probability of this type channel being open (Npo; P less than 0.01); SHR had a larger NPo (P less than 0.01). Compared with cells from Wistar and Wistar-Kyoto, cells from SHR also had the longest mean open time. The increased NPo and mean open time we observed in this K+ channel of cells from SHR could contribute, at least in part, to the increased membrane K+ permeability, reported previously.
Shoemaker
R L
RL
Department of Physiology and Biophysics, University of Alabama, Birmingham 35294.
Worrell
R T
RT
D000818:Animals; D001011:Aorta; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains
D015221:Potassium Channels; D002118:Calcium