γ-Aminobutyric acid enhancement of halothane binding in rat cerebellum

Quantitative autoradiography of C-14-halothane direct photolabeled rat cerebellum sections was performed in the presence of increasing concentrations of gamma-aminobutyric acid (GABA) or glutamate to test the hypothesis that a coupled binding equilibrium between the anesthetic and neurotransmitter exists. The results show that halothane binding was enhanced in the presence of GABA by similar to 50% in the molecular layer and to a lesser extent in the granular layer, with no change in the myelin layer. Glutamate, however, did not enhance halothane binding in any layer. These data confirm the presence of coupling, and thus suggest a direct interaction of halothane with a GABA binding protein. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.