Effect of uncoupling treatments on FSH-induced hyperpolarization of immature rat Sertoli cells from Sertoli cell-enriched cultures.

Sertoli cell-enriched cultures isolated from immature rat testes by enzymic treatments were investigated by intracellular microelectrode recordings. The hyperpolarization of cells induced by FSH was independent of the age of the rats (7-37 days) and was unchanged by exposure to a hormone-free medium or to a glycine buffer of pH 3. It was reduced by treatments which decreased the electrical coupling between cells either by an increase of intracellular calcium [i.e. calcium ionophore (A 23187, 5 x 10(-6) M), general anaesthetic (heptanol, 3.5 mM) and uncoupler of oxidative phosphorylations (carbonylcyanide m-chlorophenylhydrazone-CCmP, 10(-6) M)] or by a decrease of extracellular calcium [i.e. 0Ca + EGTA (1 mM) medium]. These effects were partly or totally reversed by a recovery period in a drug-free medium. Similar results were obtained by an exposure to trypsin (0.05%) followed by a second mechanical dispersion, but new cell hyperpolarization was induced by a new exposure to FSH. This electrophysiological study suggests an initial effect of FSH on the junctional complex between Sertoli cells, then the control by calcium of this complex.