Effect of furosemide on ion transport in the turtle bladder: evidence for direct inhibition of active acid-base transport.
The diuretic furosemide inhibits acid-base transport in the short-circuited turtle bladder. It inhibits luminal acidification when present in either mucosal or serosal bathing fluids, but decreases alkalinization only from the serosal side of the tissue. The inhibition of both acid-base transport processes is independent of ambient Cl-; and the disulfonic stilbene, SITS, an inhibitor of Cl--HCO3- exchange, fails to prevent the furosemide-elicited inhibition of alkalinization. These results preclude an absolute requirement of a furosemide-sensitive Cl--HCO3- exchange by these transport processes. The drug also interferes with the CO2-induced stimulation of acidification and alkalinization. The inhibition of the residual acidification in acetazolamide-treated, acidotic bladders, however, suggests an action at sites other than cytosolic carbonic anhydrase. Although active Na+ and Cl- reabsorption and tissue oxygen uptake are also decreased by furosemide, the rate of oxygen consumption uncoupled by 2,4-dinitrophenol is not diminished, indicating a primary inhibition of the various ion transport processes, not of metabolism. It is proposed that inhibition of transepithelial acid-base transport by furosemide in the turtle bladder includes inhibition of the acid-base pumps.
D019297:2,4-Dinitrophenol; D000086:Acetazolamide / Q000494:pharmacology; D000136:Acid-Base Equilibrium / Q000187:drug effects*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002245:Carbon Dioxide / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D004140:Dinitrophenols / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005665:Furosemide / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D010101:Oxygen Consumption / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D014426:Turtles; D001743:Urinary Bladder / Q000187:drug effects / Q000378:metabolism*
D002712:Chlorides; D004140:Dinitrophenols; D002245:Carbon Dioxide; D005665:Furosemide; D012964:Sodium; D000086:Acetazolamide; D019297:2,4-Dinitrophenol