Brain cyclic nucleotide and energy metabolite responses to subanesthetic and anesthetic concentrations of halothane.

Adult rats were exposed to 0.5, 1.0 and 1.5% halothane, delivered in air, for 1 h. Whole brain 3',5'-cyclic adenosine monophosphate (cAMP) of halothane-exposed rats showed only a slight increase relative to control values. 3',5'-Cyclic guanosine monophosphate (cGMP) was increased significantly in halothane-exposed rats, and the response was directly related to the halothane concentrations. Adenosine triphosphate (ATP) and phosphocreatine (PC) remained unchanged relative to control values. Correspondence of these values to apparent discrepancies in the literature is discussed.