Transport of organic ions in renal cortical luminal and antiluminal membrane vesicles.

Based upon saturability, kinetic analysis and specific inhibition, specific transport for the organic anion, p-aminohippurate was found in isolated luminal and antiluminal membrane vesicles from dog kidney cortex. The transport for organic anions in the two membranes differed from one another on the basis of kinetic parameters ((Km, Vmax and Ki for probenecid) and counterflow phenomenon (only the antiluminal membrane displayed the capacity to accelerate the exchange of p-aminohippurate). Also described is specific transport for the organic cation N1 methylnicotinamide in each membrane. The luminal and antiluminal transport of N1-methylnicotinamide are distinguished from one another by kinetic parameters (Km, Vmax and Ki for Darstine) and counterflow data (counterflow of N1-methylnicotinamide was observed only in the luminal membrane). The results are discussed in view of a proposed model to explain transepithelial transport of these organic ions.