Patch-clamp study of ion channels activated by GABA and glycine in cultured cerebellar neurons of the mouse.

gamma-Aminobutyric acid (GABA) and glycine receptor channels have been investigated using the patch-clamp technique. Six out of 12 membrane patches exposed to GABA as well as to glycine responded to both substances, 3 to only GABA, two to only glycine and one was insensitive to both transmitters which were applied in micromolar concentrations. Channel currents reversed at the potential predicted by the constant field equation (using Cl- activities), indicating that the charge was carried by Cl-. Although multiple-conductance states were induced by GABA as well as by glycine, the phenomenon was much more pronounced after glycine applications. GABA channel permeabilities ranged from 3.7 X 10(-14) to 6.0 X 10(-14) cm3 s-1. With Cl- distributed symmetrically at 145 mM, these values would correspond to conductances of 19 and 31 pS, respectively. Glycine channel permeabilities ranged from 3.3 X 10(-14) to 14.7 X 10(-14) cm3 s-1 (corresponding conductances 17 and 76 pS).