Potential dependency of the electrogenic Na+-pump current in bullfrog atrial muscles.
Experiments were designed to evaluate the concept that the activity of the electrogenic Na+-pump is dependent on the transmembrane potential. Cardiac muscle preparations were used because the electrogenic Na+-pump current can be recorded at different potentials with the voltage clamp method in this preparation. Electrogenic Na+-pump current was identified as the membrane current which was abolished by ouabain (5 microM) and induced by the addition of K+ or an alkali metal cation, such as Rb+, Cs+, or Li+, to the extracellular K+-free solution. Alkali metal cations other than K+ were used to eliminate the possibility that a passive membrane K+ current might be altered by changes in the K+ concentration in the vicinity of the membrane due to activation of the Na+-pump. It was concluded that the activity of the electrogenic Na+-pump current is dependent on the membrane potential.
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Hasuo
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Koketsu
D000818:Animals; D002586:Cesium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004563:Electrochemistry; D006325:Heart Atria; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008094:Lithium / Q000494:pharmacology; D008564:Membrane Potentials; D009132:Muscles / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D011892:Rana catesbeiana; D012413:Rubidium / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*
D007473:Ion Channels; D002586:Cesium; D008094:Lithium; D012964:Sodium; D012413:Rubidium