Single voltage-dependent and outward rectifying K+-channels in isolated rat heart cells |
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Authors: | W Schreibmayer H A Tritthart G Zernig H M Piper |
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Institution: | (1) Universitäts-Institut für Medizinische Physik und Biophysik, A-8010 Graz, Austria;(2) Physiologisches Institut, Universität Göttingen, D-3400 Göttingen, Germany |
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Abstract: | 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
.Ba2+ and Cs+ block the channel activity.These results clearly demonstrate the existence of K+-selective outward rectifying conductance pathways in rat ventricular myocytes. |
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Keywords: | K+-channels patch-clamp heart |
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