The effects of n-alcohols on evoked synaptic potentials in rat hippocampalslices: Hill coefficients account for the cut-off phenomenon

The anesthetic potencies of n-alcohols increase progressively with lengthen ing of the carbon chain and then disappear at a cut-off point of a longer-c hain n-alcohol. In order to assess the mechanisms for cut-off in mammalian central nervous system, the effects of a series of n-alcohols (C-2-C-11) we re examined on the evoked synaptic potentials of the rat. hippocampal prepa ration in vitro. The n-alcohols (C-2-C-10) reduced the slope of the excitat ory post-synaptic potential in a concentration-dependent manner, and the in hibitory potencies enhanced as a function of carbon chain length. The effec t disappeared at n-undecanol (C-11). The Hill coefficients of the concentra tion-response curves of the n-alcohols negatively correlated with the numbe r of carbon atoms. The decrease in the Hill coefficient could account for t he cutoff phenomenon, indicating that the results can support the anestheti c pocket hypothesis. (C) 2000 Elsevier Science Ireland Ltd. hll rights rese rved.