[A quantitative study of the nonspecific component in p-aminohippurate transport in the apical membrane vesicles]

Separate components of the p-aminohippurate (PAH) nonspecific uptake were studied quantitatively using brush border membrane vesicles of the rat kidney cortex. It is shown that nonspecific PAH uptake is due only to membrane surface sorption, when diffusion and the Donnan ion distribution take no part in PAH uptake by vesicles. The magnitude of sorption depends on the incubation time and may reach as much as 25% of equilibrium value of the total uptake of PAH.