Effect of ethanol on the water permeability and short-circuit current of the urinary bladder of the toad and the response to vasopressin, adenosine-3',5'-monophosphate and theophylline.

The effects of ethanol on the water permeability and short-circuit current of the isolated urinary bladder of the toad, Bufo marinus, were investigated. Ethanol alone did not alter the flow of water along an osmotic gradient. The increase in osmotic water flow caused by vasopressin, theophylline or cyclic adenosine-3',5'-monophosphate was inhibited by 4 to 40 mg per ml of ethanol in the mucosal or serosal bathing medium. The inhibition was more marked when ethanol was added to the serosal bathing medium, in spite of the increase in the osmotic gradient across the toad bladder caused by the ethanol. Ethanol had no effect on the increase in sodium transport (short-circuit current) due to vasopressin, although there was a significant inhibition of base-line short-circuit current. It is possible that the water diuresis due to ethanol may result in part from an inhibition of the effect of vasopressin on the collecting duct.