Spontaneous mechanical activity in depolarized frog ventricle.

Abstract

Spontaneous mechanical activity was produced in depolarized frog ventricle by bathing the tissue in a solution with low Na, low Ca and high K+. The contractions were inhibited by depleting the tissue of Ca first, but they were relatively insensitive to changes in either extracellular [Ca++] or [Ca++]/[Na+]2. They were terminated very rapidly by raising [Na+] to 40 mM. Local anesthetics enhanced the spontaneous activity in proportion to the concentration of their free base form. These contractions occurred relatively rhythmically for several hours. Since the preparation was multicellular, a mechanism for intercellular communication without change in membrane potential seemingly existed.