EFFECT OF CALCIUM-CHANNEL BLOCKER DILTIAZEM ON SOME DEPRESSANT ACTIONS OF ETHANOL IN UCHA AND UCHB RATS

Rats genetically selected for their different ethanol voluntary consum ption, UChA (low consumer) and UChB (high consumer) were used. Naive U ChA and UChB rats or submitted to ethanol chronic exposure, received a n IP dose of ethanol (2.76 g/kg) alone or 30 min after an oral dose of diltiazem (10 mg/kg), a calcium channel blocker. A significant potent iation of the narcosis and hypothermia induced by the dose of ethanol was observed in UChA diltiazem-pretreated rats not previously exposed to ethanol, while no potentiation in narcosis time appears in UChA rat s chronically exposed to ethanol that acquire tolerance. In the UChB l ine of rats, diltiazem did not potentiate ethanol depressant actions i n naive or chronic ethanol-exposed rats. Diltiazem did not modify etha nol blood levels. These results indicate that the inhibition of voltag e-dependent calcium channels can exagerate ethanol-induced effects in naive rats but not when tolerance was developed. Results suggest that UChB rats may have some innate tolerance that may be due to genetic di fference in calcium channel function. Copyright (C) 1997 Elsevier Scie nce Inc.