A Calcium-Activated Cation-Selective Channel in Rat Cultured Schwann Cells

Calcium -activated channels, in the plasm a membrane of rat cultured Schwann cells were studied in isolated ‘inside-out’ membrane patches. With identical (150 mM NaCl) solutions on either side of the membrane, a single channel conductance of 32 pS was calculated for inward current; the conductance was somewhat less for outward current. The channel is about equally permeable to sodium and potassium ions, bu t is not detectably permeable to either chloride or calcium. Under our experimental conditions the channel is activated by high (more than 10-4 m) concentrations of calcium and is sensitive to voltage, channel activity increasing with membrane depolarization.