Calcium-induced spikes in cultured pigment epithelium of chick retina.

Resting membrane potentials, electrical resistance, and coupling of chick retinal pigment epithelium cells in tissue culture have been measured with micropipette electrodes. Topical application of NaCl, KCl, MgCl2, and CaCl2 produce rapid, reversible changes in the membrane potentials of these cells. CaCl2 uniquely induces a slow hyperpolarizing wave that can lead to barrages of depolarizing action potentials or spikes and a slow, reversible vacuolization of the cells.