Accumulation of Lead by Renal Slices in the Presence of Organic Anions

Abstract

Abstract

In vitro uptake of lead by rabbit renal cortical slices was measured using ²⁰³Pb. In protein-free medium, steady-state slice-to-medium ratios were 30-70. The addition of protein (2 g/dl) or cysteine (11.5 or 23 μM) markedly reduced this ratio. All other experiments were performed with protein-containing medium. Cysteine or citrate, 113 μM, significantly increased the slice-to-medium ratio by 12-19%, but addition of serum ultrafiltrate had no effect. Metabolic inhibitors significantly reduced the ratio by 12%, but because this figure was similar to the percentage swelling by the slices, there was no effect on the mass of lead accumulated. The inhibitors had no significant effect on the increment in S/M ratio produced by cysteine or citrate. We conclude that lead cotransport into renal slices with low-molecular-weight organic ligands of plasma is very small compared to the uptake due to active transport of free ionic lead.