The effects of amiloride and ouabain on urinary acidification by turtle bladder.
To investigate the mechanism by which amiloride inhibits urinary acidification, its effects on H+ secretion were examined in the isolated urinary bladder of the fresh water turtle. In short-circuited turtle bladders amiloride inhibited H+ secretion by 30% and Na+ transport by 100%. Maximal inhibition was reached at 10(-4) M amiloride for both transport systems. In contrast to amiloride, ouabain did not affect H+ secretion despite complete inhibition of Na+ transport. In bladders first treated with ouabain amiloride failed to inhibit H+ secretion and in bladders first treated with amiloride, the inhibition of H+ secretion was partially reversed by ouabain. The inhibition of H+ secretion by amiloride is attributed to hyperpolarization of the luminal cell membrane and the imposition of a voltage opposing the movement of protons in the active transport pathway.
D000136:Acid-Base Equilibrium / Q000187:drug effects; D000584:Amiloride / Q000494:pharmacology*; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D004347:Drug Interactions; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D010042:Ouabain / Q000494:pharmacology*; D011719:Pyrazines / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism; D014426:Turtles / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism*; D014556:Urine / Q000187:drug effects*
D001639:Bicarbonates; D011719:Pyrazines; D010042:Ouabain; D000584:Amiloride; D006859:Hydrogen; D012964:Sodium