Halothane depresses action potential conduction in hippocampal axons

General anesthetics are thought to depress the central nervous system (CNS) by acting at synapses; however, only a few studies have compared effects on axonal conduction with effects on synaptic responses using mammalian CNS preparations. The present study used glutamate receptor antagonists (CNQX/APV) or low calcium to block synaptic transmission, allowing Schaffer-collateral axon fiber volleys to be recorded from rat hippocampal brain slices. Since fiber volleys are compound action potentials, they provide a measure of axonal conduction in Schaffer-collateral fibers. Clinical concentrations of the inhalational anesthetic, halothane (1 rat MAC, 1.2 vol.%), produced an 18±2.3% depression of fiber volley amplitudes (mean±S.D.; p