Renal Apical Membrane Sodium-Hydrogen Exchange in Genetic Salt-Sensitive Hypertension

Inbred Dahl/Rapp salt-sensitive and salt-resistant rats differ in their blood pressure response to dietary salt. We studied sodium-hydrogen (Na-H) exchanger kinetics in renal brush border membrane vesicles prepared from both strains either a 1% or 8% NaCl diet. Kinetics measurements were made with the acridine orange fluorescence quenching technique in vesicles prepared at pH 6.0. The initial Na-H exchange rate was measured using preparations with similar initial quench values. The maximal transport rate (Vmax, fluorescence units per second per milligram protein [±SEM]) in salt-sensitive rats on a 1% NaCl diet was significantly lower than that in salt-resistant rats (36.9±4.4 versus 51.8±5.5, respectively, P