Effect of ethanol on urine output in rats.

Experiments were carried out to delineate the effect of ethanol on urine output in rats. Ethanol (0.75-6.0 g/kg IG) had a dose dependent effect on urine output in hydrated animals. Compared to control animals, moderate (1.50, 2.50 g/kg) doses of ethanol administered intragastrically, increased urine volume during the first hour after treatment and decreased urine osmolality. Large doses of ethanol (4-6 g/kg) decreased urine output and increased urine osmolality (at 1 hr post-treatment) compared to a control group. Treatment of rats with 2.5-5.0 g/kg/day ethanol for 15 days produced tolerance to ethanol diuresis. The degree of tolerance was dose related. Significant tolerance developed with 4 days of 5.0 g/kg ethanol treatment. Loss of tolerance was also rapid. Tolerance to ethanol-induced diuresis was no longer evident 3 days after in rats treated with 5.0 g/kg of ethanol daily for 2 weeks.