Development of tolerance to ethanol-induced tachycardia in rats.

Development of tolerance to ethanol was examined using heart rate as a measure. Ethanol-treated rats were infused IG with 8-11 g/kg/day (in 3 divided doses), control rats received similar infusions of either equicaloric dextrin-maltose or water (equivolumetric) for a period of 17 days. On days 1, 5, 9, 13 and 17 of treatment heart rate was recorded before and at 10, 20 and 30 minutes after injection of a challenge dose of 2 g/kg ethanol, dextrin-maltose or water. The tachycardia produced by ethanol increased with days of chronic treatment to a maximum on the 9th day of treatment. Significant tolerance to the tachycardia was evident only on the 17th day of treatment. Neither control showed significant changes in heart rate.