ACTION POTENTIALS OF OYSTER MYOCARDIUM

Membrane resting and action potentials of the oyster heart were studied, using both an ultramicroelectrode and a suction electrode. Intracellular action potential and the monophasic extracellular action potential led off from the suction electrode show very similar patterns. Action potential can be classified into two types, but they all have a basic slow potential change superimposed by a rapid spike component. The close similarity of action potential to the vertebrate smooth muscle action potential or the pacemaker potential was discussed. With the application of picrotoxin, remarkable prolongation of action potential resembling the vertebrate cardiac action potential was obtained.