LEAD AND CALCIUM DISTRIBUTIONS IN BLOOD, PLASMA, AND MILK OF THE LACTATING MOUSE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 95  (1) , 81-89
Abstract
Although it has been established that Pb is transferred in milk from mother to suckling offspring, the physiological processes and parameters involved are not well understood. Single i.v. doses (0.2 mg/kg) oral doses (2 mg/kg) of radiolabeled Pb were administered to lactating and nonlactating female mice, and Pb concentrations in blood, plasma and milk were determined during a 21-day period. Large differences in Pb elimination were observed between lactating and nonlactating mice. A significant fraction (25%) of the initial maternal dose (absorbed dose) was transferred to the suckling pups. The ratio of Pb concentration in milk to Pb concentration in plasma was found to be nearly constant over time. The milk-to-blood concentration ratios decreased during the same period. The Pb concentration in milk exceeded the plasma concentration by a factor of approximately 25, indicating that there is a physiological process(es) which establishes a large milk-to-plasma concentration ratio. A similar Ca concentration ratio was observed. Pb concentration is a more accurate index for the estimation of milk Pb concentration than is whole blood Pb concentration.

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