[Transmembrane ionic currents in smooth muscle cells of rat tail artery].
Whole-cell currents in single smooth muscle cells freshly isolated from the rat tail artery have been studied using patch-clamp recordings techniques. Outward current evoked by depolarizing steps from -70 mV consisted of the initial fast and subsequent sustained components. The former was inhibited by 10 mM nifedipine and Ca(2+)-free solution application whereas the latter decreased by only 16% under these conditions. Caffeine at 4 mM abolished the fast component and only slightly reduced the sustained component. Both component were inhibited by 1 mM TEA+. Adding 10 mM EGTA to the pipette solution abolished the fast outward current. In the presence of 10 mM TEA+ and 4 mM 4-AP an inward current was unmasked. These results suggest that the outward current in these cells is carried mainly via delayed rectifier and Ca(2+)-activated K(+)-channels. 4-AP inhibited the sustained component and had no effect on the initial fast outward current, thus A-current is apparently absent.
Reznikov
V L
VL
A.A. Bogomoletz Institute of Physiology, National Academy of Science of Ukraine, Kiev.
Shuba
M F
MF
D000818:Animals; D001158:Arteries / Q000166:cytology; D002462:Cell Membrane / Q000502:physiology; D007473:Ion Channels / Q000502:physiology; D017136:Ion Transport / Q000502:physiology*; D008297:Male; D009130:Muscle, Smooth / Q000098:blood supply* / Q000166:cytology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D013623:Tail / Q000098:blood supply*
D007473:Ion Channels