title: Adaptation of inner medullary collecting duct vacuolar H-adenosine triphosphatase to chronic acid or alkali loads in the rat.
abstract: Acidosis increases and alkalosis decreases proton secretion in the inner medullary collecting duct (IMCD). We examined the mechanism of this adaptation by studying the immunocytochemical distribution of the vacuolar H-adenosine triphosphatase (ATPase) in the IMCD from rats subjected to acid or alkali loads for a mean duration of 4 and 9 days. For immunocytochemical staining, a monoclonal antibody to the 31-kD subunit of the bovine kidney vacuolar H-ATPase was used. Intercalated cells were present only in the initial IMCD, and the principal cells and IMCD cells showed no appreciable H-ATPase staining under any experimental conditions. We found significant adaptive changes in the distribution of H-ATPase in the intercalated cells of the IMCD. H-ATPase staining in acid-loaded rats shifted from cytoplasmic vesicles to apical plasma membrane, whereas in alkali-loaded rats cytoplasmic vesicular staining was enhanced and staining of plasma membrane disappeared. These adaptive changes were most prominent on day 4 of acid-loaded and days 4 and 9 of alkali-loaded rats. Our results indicate that translocation of the H-ATPase pump between cytoplasmic vesicles and apical plasma membrane of the intercalated cells is an important mechanism is adaptation of the IMCD to chronic acid base perturbations.
authors.affiliation: Division of Nephrology, St. Louis University Medical Center, MO 63110.
authors.forename: B
authors.initials: B
authors.lastname: Bastani
authors.forename: S
authors.initials: S
authors.lastname: McEnaney
authors.forename: L
authors.initials: L
authors.lastname: Yang
authors.forename: S
authors.initials: S
authors.lastname: Gluck
mesh_terms: D000138:Acidosis / Q000503:physiopathology*; D000222:Adaptation, Physiological; D000471:Alkalosis / Q000503:physiopathology*; D000643:Ammonium Chloride / Q000008:administration & dosage; D000818:Animals; D006863:Hydrogen-Ion Concentration; D007679:Kidney Medulla; D007685:Kidney Tubules, Collecting / Q000378:metabolism* / Q000502:physiology; D008297:Male; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017693:Sodium Bicarbonate / Q000008:administration & dosage; D014617:Vacuoles / Q000201:enzymology*
chemical_list: D000643:Ammonium Chloride; D017693:Sodium Bicarbonate; D006180:Proton-Translocating ATPases