Lead transport by renal slices and its inhibition by tin
Vander, A.J.; Mouw, D.R.; Cox, J.; Johnson, B.
American Journal of Physiology 236(4): F373-F378
1979
ISSN/ISBN: 0002-9513 PMID: 434211 Document Number: 154012
In vitro uptake of Pb by rabbit renal cortical and medullary slices was measured using 203Pb. Control cortical slice-to-medium 203Pb ratios reached steady state at approximately 90 min of incubation and ranged from 10-42. Alteration of medium [Pb](II) over 10-fold ranges did not alter the ratio, which was higher for medullary slices than for cortical. There was no difference when the carrier Pb was given as the nitrate or acetate salt, nor when the media was free of Na or bicarbonate or very low in Cl-. Accumulation was markedly reduced in the presence of chemical metabolic inhibitors (2,4-dinitrophenol, cyanide, iodoacetate), anoxia or cold. Efflux of Pb from preloaded slices was very slow and was increased by metabolic inhibitors when a Na-containing medium was used but not when the medium was Na-free. Ouabain did not alter the total accumulation of Pb, nor did increasing the medium concentration of Ca or Mg. Pb accumulation was not reduced by Hg, Cd, Cu, Zn or Sn (II); it was markedly reduced by Sn(IV), which did not alter Pb efflux or p-aminohippurate accumulation. The data indicate that Pb can enter renal cells as the free ion. They are consistent with this entry being via an active transport mechanism, but are not conclusive because the electrochemical gradient for passive movements cannot be determined. They raise the possibility that PB(II) and Sn(IV) compete for a common carrier.