CALCIUM-CHANNEL INHIBITORS ATTENUATE CONSUMPTION OF ETHANOL, SUCROSE AND SACCHARIN SOLUTIONS IN RATS

Ca2+ channel inhibitors suppress ethanol intake in various strains of alcohol-preferring rats. To test whether that inhibitory effect involves interference with the caloric consequences of preferred fluids, we compared the effects of two dihydropyridines, nicardipine and isradipine, and diltiazem, a benzothiazepine Ca2+ channel inhibitor, on intake of and preference for 10% ethanol (v/v), 13.7% sucrose (w/v, isocaloric to 10% ethanol) and non-caloric 0.02% saccharin (w/v) solutions. All of these Ca2+ channel inhibitors dose-dependently (1.25-5 mu mol/kg isradipine, 5-20 mu mol/kg nicardipine, 10-40 mu mol/kg diltiazem) inhibited ethanol intake in alcohol-preferring P rats. Nicardipine and isradipine, but not diltiazem, simultaneously increased water intake and attenuated preference for ethanol. No change in food pellet intake was found. Similar inhibition was observed with regard to sucrose and saccharin intake in Sprague-Dawley rats, although higher doses (> 10 mu mol/kg) were required to achieve that effect. No significant changes in sucrose preference, as opposed to consumption, were observed with any drug, and only nicardipine at its highest dose (20 mu mol/kg, b.i.d.) significantly (p < 0.05) decreased preference for saccharin. In conclusion, all three Ca2+ channel inhibitors significantly suppress consumption of caloric solutions of ethanol and sucrose, as well as of non-caloric saccharin solution. Although an accompanying decrease in preference is evident only for alcohol, it appears that these effects may be related to decreased palatability of flavored fluids. However, the contribution of changes in ethanol- and sucrose-induced caloric satiety cannot be ruled out.