• A Luo and K Sugiyama.
• Department of Anesthesiology, Tongji Hospital, Tongji Medical University, Wuhan 430030, China.
• Chinese Med J Peking. 2000 Sep 1;113(9):840-3.

ObjectiveTo investigate the effect of propofol combined with diazepam on the gamma-aminobutyric acid (GABA)-activated chloride current (IGABA) evoked in rat sensory neurons.MethodsWhole cell patch clamp recordings were made from cultured rat dorsal root ganglionic neurons. GABA (3 mumol/L) was applied by pressure ejection. The anesthetics were dissolved in the external solution and given by the "Y-tube" method.ResultsCo-application of propofol (0.3-3 mumol/L) and diazepam (100 nmol/L) potentiated the IGABA which was significantly larger than the sum of that potentiated by drug alone. Diazepam (100 nmol/L) shifted the concentration-response curve for the IGABA potentiation induced by propofol to the left in a parallel fashion. The EC50 value for propofol was decreased by diazepam from 7.6 +/- 1.8 mumol/L to 3.9 +/- 1.1 mumol/L (n = 9).ConclusionsOur results suggest that propofol combined with diazepam synergistically potentiates the IGABA. Diazepam-induced increase in the apparent binding affinity of propofol for the GABAA receptors is likely responsible for a clinical synergistic hypnotic action during co-application with propofol and diazepam.

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