Single voltage-dependent and outward rectifying K+-channels in isolated rat heart cells.
Studies on single K+-channel currents recorded from isolated rat heart muscle cells, in which early repolarization is known to be exceptionally fast, are reported here. A K+-channel which is blocked by TEA (tetraethylammonium) from the inside only has been found. The total open time of the channel, measured in steady-state after activation, indicated outward rectifying properties. The single channel conductance increases with depolarization from 25 pS at -70 mV to 75 pS at + 70 mV. Selectivity of the channel has also been measured and it was found that only Rb+ and K+ can permeate the channel, whereas the permeability (P) for Li+, Na+, Cl-, Mg2+, and Ca2+ is less than 0.05 times PK+. Ba2+ and CS+ block the channel activity. These results clearly demonstrate the existence of K+-selective outward rectifying conductance pathways in rat ventricular myocytes.
Schreibmayer
W
W
Tritthart
H A
HA
Zernig
G
G
Piper
H M
HM
D000818:Animals; D001464:Barium / Q000494:pharmacology; D002412:Cations; D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability; D002586:Cesium / Q000494:pharmacology; D004553:Electric Conductivity; D006321:Heart / Q000502:physiology*; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012413:Rubidium / Q000378:metabolism; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D002412:Cations; D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D002586:Cesium; D001464:Barium; D019789:Tetraethylammonium; D012413:Rubidium; D011188:Potassium