GABA-induced whole-cell currents were measured in rod bipolar cells dissociated from the adult rat retina. The patch-clamp electrode contained nystatin, which made the cell membrane electrically permeable without rupture, thus retarding the rate of diffusion of Cl– ions from the patch pipette to the cell interior. The reversal potential of the GABA-induced currents was around –70 mV at an extracellular Cl-–concentration of 149 mM. We conclude that GABA generates hyperpolarizing responses in rod bipolar cells of the rat retina.
