AJP - Renal Physiology, Vol 245, Issue 2 217-F222, Copyright © 1983 by American Physiological Society
Metabolic acidosis and parathyroidectomy increase Na+-H+ exchange in brush border vesicles
D. E. Cohn, S. Klahr and M. R. Hammerman
Na+-H+ exchange across the brush border membrane of the renal proximal
tubular cell is a mechanism for Na+ reabsorption and H+ secretion. An
electroneutral Na+-H+ exchange activity has been identified in isolated
renal brush border membrane vesicles from rat and dog kidney, and increased
Na+-H+ exchange has been measured in brush border membrane vesicles from
remnant kidneys of dogs with chronic renal failure. To ascertain whether
changes in H+ secretion by the kidney observed in chronic metabolic
acidosis and in states of altered parathyroid function might result from
altered Na+-H+ exchange across the renal cortical cellular brush border
membrane, we measured Na+-H+ exchange in brush border membrane vesicles
from kidneys of dogs with chronic metabolic acidosis and from kidneys of
thyroparathyroidectomized dogs. Increased amiloride-sensitive Na+-H+
exchange was demonstrated in brush border membrane vesicles from kidneys of
both groups of dogs, suggesting that adaptations in H+ excretion in chronic
metabolic acidosis and hypoparathyroidism might be explained by increased
activity of a renal brush border membrane Na+-H+ exchanger.
