On membrane potential and ciliary stimulation

The relation between membrane potential and ciliary beat frequency was examined in tissue cultures from frog palate and esophagus. It was found that hyperpolarization or depolarization of the ciliary cell membrane enhances ciliary beating. The induced enhancement of the ciliary beat frequency by either hyperpolarization or depolarization depends on the extracellular Ca²⁺ concentration, however, the involvement of voltage-gated calcium channels is unlikely, since blockers of voltage-gated channels at their specific concentrations did not have any effect. However, partial inhibition was achieved by a 10-50 fold increase in the concentration of blockers. Moreover, it was shown that the magnitude of ciliary activation depends on the method by which depolarization of the cell was achieved. Quinidine (1 mM) abolished ciliary enhancement induced by either hyperpolarization or depolarization. Based on these findings we conclude that the enhancement of ciliary beating is not controlled solely by the membrane potential.