Electrophysiology of collecting duct H+ secretion: effect of inhibitors

Am J Physiol. 1989 Jan;256(1 Pt 2):F79-84. doi: 10.1152/ajprenal.1989.256.1.F79.


Segments of the outer medullary collecting duct were isolated from the inner stripe of the rabbit kidney (OMCDi), perfused in vitro, and impaled across their basolateral membranes with voltage-recording microelectrodes. The disulfonic stilbene 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) (10(-4) M) and the carbonic anhydrase inhibitor acetazolamide (10(-4) M) depolarized the lumen-positive transepithelial voltage (VT) toward 0 mV when added to the bath solution. Concurrently, the basolateral membrane voltage (Vbl) hyperpolarized. The hyperpolarization of Vbl, which averaged 19.3 +/- 2.9 mV (n = 11) for SITS and 22.7 +/- 3.5 mV (n = 11) for acetazolamide, was not due to an alteration in the ionic selectivity of the basolateral membrane, which was highly Cl- selective. The hyperpolarization of Vbl could best be explained by a decrease in the intracellular [Cl-], and the associated shift in the emf for Cl- (ECl) across the basolateral membrane. The decrease in intracellular [Cl-] could be attributed to inhibition of a Cl-HCO3 antiporter in the basolateral membrane. SITS appeared to inhibit this antiporter directly, whereas the effect of acetazolamide was indirect, probably secondary to a decrease in the intracellular [HCO3-]. Finally, both SITS and acetazolamide induced or unmasked an electroneutral K+-coupled transport system in the basolateral membrane.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / pharmacology
  • Acetazolamide / pharmacology
  • Animals
  • Bicarbonates / pharmacology
  • Chlorides / metabolism
  • Electrophysiology
  • Female
  • Hydrogen / metabolism*
  • Kidney Tubules / physiology*
  • Kidney Tubules, Collecting / drug effects
  • Kidney Tubules, Collecting / physiology*
  • Potassium / pharmacology
  • Rabbits


  • Bicarbonates
  • Chlorides
  • 4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid
  • Hydrogen
  • Acetazolamide
  • Potassium