Inhibition of the rat renal Na+/H+ exchanger by beta-adrenergic antagonists.

The beta-adrenergic antagonists, alprenolol and propranolol, inhibit the Na+/H+ exchanger in rat renal brush-border membrane vesicles. Half-maximal inhibition occurs at 86 microM alprenolol and 36 microM propranolol. Similar to amiloride and Na+, propranolol protects the Na+/H+ exchanger from irreversible inhibition by the carboxyl group reagent, N,N'-dicyclohexyl-carbodiimide (DCCD). Protection is incomplete, depends on propranolol concentration, and reaches a maximum at 0.4 mM propranolol. With a comparable dose dependence, propranolol protects a 65 kDa band from labeling with 14C]DCCD. The data indicate that beta-adrenergic antagonists specifically interact with the proximal tubular Na+/H+ exchanger.