title: Modulation of antidiuretic hormone-dependent capacitance and water flow in toad urinary bladder.
abstract: To test the hypothesis that antidiuretic hormone- (ADH) dependent water permeability is associated with changes in apical membrane area, hormone-dependent water flow and capacitance changes were measured in the toad urinary bladder under a number of different conditions. Dose-response relationships for water flow (Jv) and capacitance increases (delta C) were similar from 1 to 20 mU/ml ADH. At higher concentrations, Jv reached a plateau, while delta C decreased. The decrease in delta C was prevented by elimination of the osmotic gradient across the tissue. Serosal hydrazine (10 mM) increased Jv sevenfold and delta C threefold in the presence of 1 mU/ml ADH. Mucosal NH4Cl, at constant mucosal pH, increased Jv by 50-100%, but did not significantly change delta C. In the absence of an osmotic gradient, mucosal NH+4 increased delta C by 50%. NH4Cl had no effect on hydroosmotic response to 8-bromo-adenosine 3',5'-cyclic monophosphate (cAMP). Mucosal CO2 (9%) decreased Jv by greater than 90%, and delta C by 60% with 20 mU/ml ADH. Mucosal CO2 also inhibited the hydroosmotic response to 8-bromo-cAMP. Removal of serosal Na diminished cAMP-dependent Jv and delta C. The results confirmed the close relationship between ADH-dependent water permeability and membrane capacitance. They indicate, however, that under some circumstances membrane may be retrieved from the apical surface without affecting water permeability.
mesh_terms: D000643:Ammonium Chloride / Q000494:pharmacology; D000818:Animals; D001834:Body Water / Q000378:metabolism*; D002024:Bufo marinus; D004305:Dose-Response Relationship, Drug; D005260:Female; D006834:Hydrazines / Q000378:metabolism; D009092:Mucous Membrane / Q000378:metabolism; D009994:Osmolar Concentration; D010539:Permeability; D012704:Serous Membrane / Q000378:metabolism; D001743:Urinary Bladder / Q000378:metabolism*; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D006834:Hydrazines; D000643:Ammonium Chloride; D014667:Vasopressins; C029424:hydrazine