Effect of calcium deprivation on frog skeletal muscles at different pH values.

Whole sartorius muscles from the frog were exposed to calcium-free solutions at different pH values. The depolarizations caused by these solutions were measured 1 hr after the solution change. When the pH was 7.2, the mean depolarization was 8 mV. At pH values of 5.1 and 8.5, the mean depolarizations were 1 and 17 mV, respectively. Similar experiments were carried out with solutions in which the main anion was sulfate instead of chloride. In these cases, the depolarization values caused by calcium deprivation at pH values of 7.2, 5.5, and 8.5 were 11, 4, and 20 mV, respectively.