RESUMEN
Lactose facilitated intestinal lead [Pb] absorption in fasted weanling rats yet young age and food deprivation might influence lead absorption. In overcoming such variables, adult male rats were supplied with libidum with drinking fluids containing 500 mg or 2,500 mg of Pb as lead acetate with or without 5 g of lactose per liter of water for 2 months. The presence of lactose reduced the volume of fluid intake [P < 0.001] and the net Pb ingested daily dropped by two thirds while the blood lead level increased [P < 0.01] causing a decrease in erythrocytes Porphobilinogen level and rate of gain in body weight. Lactose which increases the permeability of cell membrane of the small intestine to calcium and other divalent ions non-selectively, may well explain the enhancing effect of lactose on lead absorption