[Characteristics and interactions between glycine- and GABA-mediated responses of the frog spinal cord neurons].

Interactions between GABA and glycine receptors in dissociated neurons from the frog spinal cord lumbar enlargement were analyzed by using whole-cell patch-clamp technique. As the recordings were made without intracellular ATP, the amplitude of GABA-mediated response gradually decreased to about 50 % of its initial value. Co-application of saturating concentrations of GABA and glycine resulted in producing a total current much smaller than the sum of the two individual responses. The amplitude of the total current gradually decreased to the value of that of the glycine-mediated response. After the amplitude of GABA response got stabilized, the amplitude of current produced by co-application of 5 mM GABA and 8 microM glycine (EC50) turned out to be by 25 % larger than that of either of the individual responses and reached the level of about 80 % of their sum. These results suggest that the frog spinal cord neurons express a population of inhibitory amino acid receptors that can bind either glycine or GABA.