Different effect of diltiazem and nifedipine on some central actions of ethanol in the rat.

The effect of two Ca2+ channel inhibitors (CCIs) on ethanol-induced hypothermia and hypnosis, on tolerance formation to both effects, and on audiogenic convulsions during ethanol withdrawal was studied in rats. Nifedipine, 2 and 5 mg/kg IP, significantly augmented the hypnotic action of ethanol without affecting hypothermia. Diltiazem failed to influence either effect of the toxin. Rectal temperature did not change in ethanol-naive rats after acute injection of diltiazem or nifedipine. Both drugs dose-dependently suppressed the development of tolerance to the hypothermic effect of ethanol without affecting the tolerance to the hypnotic action. Only nifedipine markedly suppressed the audiogenic seizure response in ethanol withdrawn animals. These data suggest that Ca2+ channels play a role in both acute and chronic effects of ethanol while pointing to certain differences in behavioral effects of various CCIs.