Relationship between PAH transport and Na-K-ATPase activity in the rabbit kidney.
The relationship between Na-K-ATPase activity and p-aminohippurate (PAH) transport was examined in renal cortical slices of mixed-breed rabbits by using ouabain to vary the level of Na-K-ATPase activity. Ouabain increased passive PAH uptake, measured in the presence of probenecid. Slice homogenate Na-K-ATPase activity was inhibited by 50% with about 2 X 10(-6) M ouabain. When the concentration was 10(-5) M or above, active PAH uptake was inhibited. Lower concentrations (10(-7) and 10(-6) M) of ouabain stimulated active PAH uptake. Acetate stimulated PAH uptake when medium ouabain was less than 10(-4) M. Ouabain, 10(-5) M and higher, caused intracellular K+ to fall and Na+ to rise. The changes in active PAH uptake observed with ouabain correlated much better with changes in intracellular K+ or Na+ levels (P less than 0.01) than with changes in slice homogenate Na-K-ATPase activity. Vmax for active PAH uptake decreased with 5 X 10(-5) M ouabain, and tended to increase with 10(-7) M ouabain. Ouabain did not alter Km for active PAH uptake. The data support the hypothesis that there is a functional link between active PAH transport and Na-K-ATPase activity. This linkage may be an indirect one mediated by changes in intracellular cation concentrations.
D000618:Aminohippuric Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001693:Biological Transport, Active / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D007668:Kidney / Q000201:enzymology / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D011817:Rabbits; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D010130:p-Aminohippuric Acid / Q000378:metabolism*
D000618:Aminohippuric Acids; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D010130:p-Aminohippuric Acid