Chloride channels activated by gamma-aminobutyric acid in normal bovine lactotrophs.

The effect of gamma-aminobutyric acid (GABA) on normal bovine lactotrophs was investigated using the patch clamp technique. GABA application (1-10 microM) induced fluctuations of membrane current, accompanied by an increase in inward current. The mean conductance of GABA-activated channels was estimated to be 19 pS from statistical analysis of these fluctuations whereas the mean conductance for GABA-activated single ion channels was 16 pS. The reversal potential of the current was near to the equilibrium potential for chloride ions. These results indicate that the one possible mechanism for inhibition of prolactin release induced by GABA is probably mediated by activation of chloride channels.