V-H+ -ATPase Translocation During Blood Alkalosis in Dogfish Gills: Interaction With Carbonic Anhydrase and Involvement in the Postfeeding Alkaline Tide

Am J Physiol Regul Integr Comp Physiol. 2007 May;292(5):R2012-9. doi: 10.1152/ajpregu.00814.2006. Epub 2007 Jan 4.

Abstract

We investigated the involvement of carbonic anhydrase (CA) in mediating V-H(+)-ATPase translocation into the basolateral membrane in gills of alkalotic Squalus acanthias. Immunolabeling revealed that CA is localized in the same cells as V-H(+)-ATPase. Blood plasma from dogfish injected with acetazolamide [30 mg/kg at time (t) = 0 and 6 h] and infused with NaHCO(3) for 12 h (1,000 microeq.kg(-1).h(-1)) had significantly higher plasma HCO(3)(-) concentration than fish that were infused with NaHCO(3) alone (28.72 +/- 0.41 vs. 6.57 +/- 2.47 mmol/l, n = 3), whereas blood pH was similar in both treatments (8.03 +/- 0.11 vs. 8.04 +/- 0.11 pH units at t = 12 h). CA inhibition impaired V-H(+)-ATPase translocation into the basolateral membrane, as estimated from immunolabeled gill sections and Western blotting on gill cell membranes (0.24 +/- 0.08 vs. 1.00 +/- 0.28 arbitrary units, n = 3; P < 0.05). We investigated V-H(+)-ATPase translocation during a postfeeding alkalosis ("alkaline tide"). Gill samples were taken 24-26 h after dogfish were fed to satiety in a natural-like feeding regime. Immunolabeled gill sections revealed that V-H(+)-ATPase translocated to the basolateral membrane in the postfed fish. Confirming this result, V-H(+)-ATPase abundance was twofold higher in gill cell membranes of the postfed fish than in fasted fish (n = 4-5; P < 0.05). These results indicate that 1) intracellular H(+) or HCO(3)(-) produced by CA (and not blood pH or HCO(3)(-)) is likely the stimulus that triggers the V-H(+)-ATPase translocation into the basolateral membrane in alkalotic fish and 2) V-H(+)-ATPase translocation is important for enhanced HCO(3)(-) secretion during a naturally occurring postfeeding alkalosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkalosis / blood*
  • Animals
  • Carbonic Anhydrases / metabolism*
  • Dogfish / blood
  • Dogfish / metabolism*
  • Feeding Behavior / physiology
  • Gills / enzymology*
  • Hydrogen-Ion Concentration
  • Postprandial Period / physiology*
  • Protein Transport
  • Sodium Bicarbonate / pharmacology
  • Time Factors
  • Vacuolar Proton-Translocating ATPases / metabolism*

Substances

  • Sodium Bicarbonate
  • Vacuolar Proton-Translocating ATPases
  • Carbonic Anhydrases