RESPONSE OF INTERCALATED CELLS TO CHLORIDE DEPLETION METABOLIC ALKALOSIS

We examined the effect of Cl- depletion metabolic alkalosis (CDA) on H+-ATPase and band 3 protein localization in intercalated cells (IC) of the rat cortical collecting duct (CCD) and the outer medullary collecting duct (OMCD). After 30 min of peritoneal dialysis against 0.15 M NaHCO3 to produce CDA, or Ringer bicarbonate to serve as controls (CON), both groups were infused intravenously with an 80 mM Cl- solution for 90 min. For CDA vs. CON, physiological parameters were as follows: plasma total CO2, 38.0 +/- 1.1 vs. 27.8 +/- 0.6 meq/l (P < 0.001); urinary total CO2 excretion, 141 +/- 89 vs. 20 +/- 3 neq. min-1.100 g body wt-1; and urinary Cl- excretion, 20 +/- 10 vs. 486 +/- 144 neq.min-1.100 g body wt-1 (P < 0.001). H+-ATPase was localized in thin sections using a rabbit polyclonal antibody against the 70-kDa subunit of bovine brain H+-ATPase. Band 3 protein was localized using a polyclonal antibody against the 43-kDa subunit of the cytoplasmic domain of human erythrocyte band 3 protein. In CON rats, H+-ATPase localized along the apical plasma membrane and over the apical cytoplasmic vesicles of type A ICs in the CCD and ICs of the OMCD. H+-ATPase was observed along the basolateral plasma membrane and over cytoplasmic vesicles throughout type B ICs. In CDA rats, H+-ATPase was only observed over apical cytoplasmic vesicles in type A ICs and in the majority of OMCD ICs. In type B ICs, H+-ATPase staining was intensified along the basal plasma membrane in CDA. Band 3 protein was consistently localized in the basolateral plasma membrane of all type A cells in the CCD and ICs of the OMCD in both CON and CDA. In summary, stimulation of HCO3- secretion in rats caused withdrawal of H+-ATPase from the apical plasma membrane and storage in apical cytoplasmic vesicles of ICs of the OMCD and type A ICs of the CCD. H+-ATPase appeared to be inserted into the basal plasma membrane of type B ICs. These findings suggest that, during correction of CDA, proton secretion by type A and OMCD ICs is suppressed and proton transport across the basolateral plasma membrane of type B ICs is stimulated.