Chronic hypercapnia enhances Vmax of Na-H antiporter of renal brush-border membranes.

Chronic hypercapnia is associated with increased proximal HCO3 reabsorption that is thought to be mediated by a Na-H antiporter. We hypothesized that chronic hypercapnia would be associated either with increased Vmax or with decreased Km of the Na-H antiporter. To test this hypothesis we made rabbits hypercapnic for 48 h by exposure to 10% CO2.