The Effects of Acidosis and Bicarbonate on Action Potential Repolarization in Canine Cardiac Purkinje Fibers

I N T R O D U C T I O N Action potential repolarization in hear t cells results f rom the complex interaction o f a large n u m b e r o f ionic events. The extent to which these events are influenced or otherwise modula ted by the acid-base state of the extracellular fluid remains largely a matter of conjecture. The present study was under taken to determine the individual actions o f hyd rogen and bicarbonate ions on action potential repolarization under experimental conditions simulating those o f in vivo acidosis, i.e., increased CO2 tension (respiratory acidosis) or decreased extracellular bicarbonate concentrat ion (metabolic acidosis). Previous studies o f the effects o f acidosis on the format ion of cardiac action potentials have yielded conflicting results. For example, Poole-Wilson and J. GEN. PHYSIOL. ~) The Rockefeller University Press 9 0022-1295/79/02/0199.2051.00 199 Volume 73 February 1979 199-218 on Jne 1, 2017 D ow nladed fom Published February 1, 1979