Ureteral Obstruction Decreases ATP Dependent H⁺-Pump Activity of Rabbit Renal Outer Medulla

Abstract

KANEMITSU, H., SASAKI, S., AKIBA, T. and MARUMO, F. Ureteral Obstruction Decreases ATP Dependent H⁺-Pump Activity of Rabbit Renal Outer Medulla. Tohoku J. Exp. Med., 1990, 160 (3), 223-229 -Ureteral obstruction has been known to cause a renal acidification defect. To determine the underlying mechanisms of this defect, vacuolar-type H⁺-pump activity of the membrane vesicles taken from the rabbit renal outermedulla was measured in 24hr obstructed and contralateral kidneys. H⁺-pump activity measured by acridine orange quenching method was resistant to oligomycin (10μg/ml), vanadate (0.1mM), and the absence of ambient K⁺, and it was highly sensitive to N-ethylmaleimide (0.5mM) and dicyclohexylcarbodiimide (0.2mM). H⁺-pump activity was 6.69±1.40 in the obstructed kidney, which was significantly lower than 10.32±1.88% AFU/mg•min in the contralateral kidney. In sham-operated rabbits, H⁺-pump activities were not different in both kidneys. Passive H⁺/OH^- permeability measured by the rate of dissipation of the imposed pH gradient was not different in obstructed and contralateral kidneys. These results suggest that ureteral obstruction decreases vacuolar-type H⁺-pump activity of the kidney outermedulla, and this decrease may contribute to the distal acidification defect of obstructed uropathy.