Effect of glutaraldehyde on hydrosmotic response of toad bladder to vasopressin

Abstract

The present study investigates the time-, dose-, and temperature-dependence of glutaraldehyde action on the permeability to water of the toad bladder. Bladders preincubated with increasing concentrations of glutaraldehyde become progressively desensitized to the hydrosmotic action of vasopressin (ADH), theophylline, and dibutyryl adenosine 3',5'-cyclic monophosphate (dibutyryl cAMP). The ADH response was reduced by 50% with 0.03% glutaraldehyde applied to the serosal side for 10 min at 4 degrees C. Sixfold higher doses of glutaraldehyde were required with mucosal application. Bladders partially fixed with low-dose glutaraldehyde exhibit a markedly prolonged duration of action of ADH. Bladders fixed with higher doses of glutaraldehyde in the presence of ADH retain a high permeability to water for prolonged periods even in the absence of ADH. This action of glutaraldehyde to stabilize the hormone-induced water channels is also considerably more effective with serosal than with mucosal application. As the rate-limiting permeability barrier for water affected by ADH is known to be located in the apical membrane, these findings suggest that glutaraldehyde exerts its action from an intracellular position. It is postulated that glutaraldehyde stabilizes the ADH-induced channels by cross-linkage of amino groups and other reactive sites at the cytoplasmic surface of the apical membrane and/or by inactivating the intracellular machinery responsible for the dispersal or removal of water channels in the hormone target cell.