The Journal of General Physiology, Vol 68, 145-157, Copyright © 1976 by The Rockefeller University Press
Spontaneous mechanical activity in depolarized frog ventricle
S Winegrad
Spontaneous mechanical activity can be produced in depolarized frog
ventricle by bathing the tissue in a solution with low Na, Iow Ca, and high
K+. The contractions can be inhibited by depleting the tissue of Ca first,
but they are relatively insensitive to changes in either extracellular
[Ca++] or [Ca++]/[Na+]2. They are terminated very rapidly by raising [Na+]
to 40 mM. Local anesthetics enhance the spontaneous activity in proportion
to the concentration of their free base form. These contractions occur
relatively rhythmically for several hours. Since the preparation is
multicellular, this suggests a mechanism for intercellular communication
without change in membrane potential.