Effects of 4-acetamido-4'-isothiocyano-2,2'-disulfonic stilbene (SITS) in bath or lumen on p-aminohippurate (PAH) transport by isolated perfused snake (Thamnophis spp.) distal-proximal renal tubules were studied. Addition of SITS to the bath in concentrations as low as 10-10 M irreversibly depressed net PAH secretion. Addition of 10-4 M SITS in the bath depressed net PAH secretion by about 60% without affecting apparent permeability of luminal membrane to PAH (PL) or net fluid absorption. Cellular PAH concentration was reduced by about 70% at this time but was still greater than that in the bath. Apparent permeability of peritubular membrane, determined from PAH efflux from tubules with oil-filled lumens, was unchanged even with 10-3 M SITS in bath. These data indicate that SITS in the bath inhibits PAH transport from bath into cells without enhancing passive efflux from cells to bath. Addition of 10-4 M SITS to the lumen alone depressed net PAH secretion and PL by about 60%, but this depression was reversed when SITS was removed from the lumen. These data suggest that PAH moves from cells to lumen by a mediated process distinctly different from that for transport into cells from bath.
|Original language||English (US)|
|Journal||American Journal of Physiology - Renal Fluid and Electrolyte Physiology|
|State||Published - 1980|
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