Extracellular potassium accumulation in voltage-clamped frog ventricular muscle

The Journal of Physiology
L Cleemann, M Morad


1. Application of voltage clamp pulses (1--10 sec) to frog ventricular strips causes temporary changes in the extracellular K concentration. 2. The changes in the extracellular K concentration can be estimated from (a) slowly decaying post-clamp after-potentials, (b) changes in the action potential duration, and (c) measurements with a K-selective micro-electrode. 3. The depolarization of the resting potential and the shortening of the action potential are present in approximately the same proportions during voltage-clamp induced extracellular K accumulation and during perfusion with a K-ricn Ringer solution but small consistent differences are noticed. 4. The measurements of the after-potential, the action potential shortening, and the K-electrode response were analysed as indicators of extracellular K+ activity and it was concluded that the after-potential provides the most convenient and reliable estimate of the absolute magnitude of the voltage-clamp induced extracellular K accumulation. 5. The depolarizing after-potentials decay more slowly than the hyperpolarizing after-potentials but it is found that this reflects the selectivity of the membrane to K+ concentrations as predicted by the Nernst or the Goldman equations. 6....Continue Reading


Jan 1, 1986·The Journal of Membrane Biology·Y Tourneur
Jul 1, 1982·IEEE Transactions on Bio-medical Engineering·J P Drouhard, F A Roberge
Sep 1, 1980·Pflügers Archiv : European journal of physiology·D DiFrancescoW Trautwein
Apr 1, 1980·Pflügers Archiv : European journal of physiology·J VereeckeE Carmeliet
Sep 1, 1983·Pflügers Archiv : European journal of physiology·T Klitzner, M Morad
Oct 1, 1985·Pflügers Archiv : European journal of physiology·L Tung, M Morad
Oct 1, 1980·Circulation Research·A VleugelsE Carmeliet
Dec 1, 1984·Pflügers Archiv : European journal of physiology·D DiFrancescoS Visentin
Aug 12, 1999·Clinical and Experimental Allergy : Journal of the British Society for Allergy and Clinical Immunology·Y G Yap, A J Camm
Sep 1, 1983·Pflügers Archiv : European journal of physiology·T Klitzner, M Morad

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