Na⁺/H⁺ Antiport in Renal Brush Border Membrane Vesicles from Rabbit Kidneys with Experimental Fanconi Syndrome

Abstract

Na⁺/H⁺ antiport was investigated in renal brush border membrane vesicles prepared from control and anhydro-4-epitetracycline-administered (100 mg/kg body weight) rabbits. Proton transport and resulting pH-gradient (ΔpH) across membrane were measured using acridine orange as a fluorescent probe. Our system to evaluate Na⁺/H⁺ antiport appeared to be consistent with previous descriptions on Na⁺/H⁺ antiporter in renal brush border membrane vesicles. We employed pH jump studies to measure initial ratesof H⁺ transport as a function of Na⁺ concentration. Kinetic analyses indicate that apparent K_Na or V_max in vesicles from anhydro-4-epitetracycline-administered rabbits was not significantly different from that in control (K_Na=4.3±0.4 vs. 5.6±2.2 mM, V_max=0.161±0.44 vs. 0.194±0.023 pH units/3s, respectively). These results support the conclusion that anhydro-4-epitetracycline dose not affect renal Na⁺/H⁺ antiporter.