title: Diuretics stimulate H+ secretion in turtle urinary bladder.
abstract: The effect of various diuretics on H+ secretion was studied in the isolated short-circuited urinary bladder of the turtle. Mucosal (urinary) chlorothiazide stimulated H+ secretion promptly, from 1.33 +/- 0.24 to 3.03 +/- 0.25 mueq/h (P less than 0.001). The effect was rapidly reversible upon washout of the drug, H+ returning to control levels, 1.37 +/- 0.26 mueq/h (P less than 0.001). Similar effects were observed with mucosal hydrochlorothiazide and mucosal ethacrynic acid/cysteine. Stimulation of H+ secretion occurred in the presence or the absence of exogenous CO2, in the presence or absence of mucosal Na+ and during inhibition of Na+ transport by ouabain. There was no stimulation of H+ secretion by uncomplexed ethacrynic acid or by mucosal furosemide. The nondiuretic sulfonamide, sulfasoxizole, and the nonsulfonamide buffer, borate, had no effect on H+ SECRETION. These observations indicate that the stimulatory effect of diuretics on H+ secretion is not related to active sodium transport, transepithelial electrical potential, or the buffering capacity of the drugs. Since the transepithelial pH gradient at which active H+ secretion was abolished was identical for chlorothiazide-treated tissues (2.68 pH U) as for control tissues (2.65 pH U, NS), the data suggest that the protonmotive force of the H+ pump was unaffected by the diuretic. This observation, plus the rapid onset and reversibility of the drugs, is consistent with an effect on the mucosal membrane to increase H+ conductance (K). The findings raise the possibility that direct enhancement of renal H+ secretion may play a role in the metabolic alkalosis induced by some diuretics.
mesh_terms: D000818:Animals; D001881:Borates / Q000494:pharmacology; D002740:Chlorothiazide / Q000494:pharmacology; D003545:Cysteine / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology*; D004553:Electric Conductivity; D004976:Ethacrynic Acid / Q000494:pharmacology; D005665:Furosemide / Q000494:pharmacology; D006852:Hydrochlorothiazide / Q000494:pharmacology; D006859:Hydrogen / Q000378:metabolism / Q000652:urine*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D009092:Mucous Membrane / Q000187:drug effects; D012964:Sodium / Q000502:physiology; D013444:Sulfisoxazole / Q000494:pharmacology; D013997:Time Factors; D014426:Turtles / Q000652:urine*; D001743:Urinary Bladder / Q000187:drug effects* / Q000378:metabolism
chemical_list: D001881:Borates; D004232:Diuretics; D006852:Hydrochlorothiazide; D013444:Sulfisoxazole; D002740:Chlorothiazide; D005665:Furosemide; D006859:Hydrogen; D012964:Sodium; D003545:Cysteine; D004976:Ethacrynic Acid