Intracellular potassium and chloride activities in frog heart muscle.

Abstract

We have been using K+ and Cl- liquid ion exchanger microelec-trodes to measure intracellular activities of K+ and Cl- in frog heart. In these studies we have used three kinds of heart muscle: ventricle, atrium and sinus venosus. The preparations are small pieces of tissue cut from the heart and pinned down in a chamber where they are superfused with frog Ringers solution. The ventricular and atrial preparations are quiescent unless stimulated; in these experiments they are driven at a frequency of 0.5 stimuli/sec. The sinus venosus preparations are spontaneously active.