Depolarizing effects of the ionophores X-537A and A23187 and their relevance to secretion.

The ionophore X-537A depolarized frog skeletal muscle fibres about 10 mV in 10 min and a further 30 mV or so over the next 50 minutes. With A23187, depolarization was relatively feeble and delayed in onset but was hastened when calcium was removed from the bathing medium. The results support conjecture that some functional responses to these ionophores are attributable, in part, to depolarization.