Renal reabsorption and secretion of delta-aminolevulinic acid in the rat.

Renal mechanisms for handling delta-aminolevulinic acid (ALA) were investigated in control and lead-exposed rats infused with ALA at a range of rates which produced plasma ALA as high as 2380 ng/mL. The presence of both reabsorption and secretion mechanisms was demonstrated. Reabsorption is the more efficient of the two mechanisms at low plasma ALA concentrations, and masks secretion in this range. Net secretion is observed at very high plasma ALA concentrations. Exposure to up to 2000 micrograms lead/mL of drinking water for 12 to 18 months had no measurable effect on net ALA excretion at a given plasma ALA level.