Keller C A, Doherty R A
J Lab Clin Med. 1980 Jan;95(1):81-9.
Although it has been established that lead 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) or p.o. doses (2 mg/kg) of radiolabeled lead were administered to lactating and nonlactating female mice, and lead concentrations in blood, plasma, and milk were determined during a 21-day period. Large differences in lead 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 lead concentration in milk to lead concentration in plasma was found to be nearly constant over time. However, the milk-to-blood concentration ratios decreased during the same period. Furthermore, the concentration of lead in milk exceeded the plasma concentration by a factor of approximately 25, indicating that there is a physiological process(es) which established a large milk-to-plasma concentration ratio. A similar calcium concentration ratio was also observed. It is concluded that plasma lead concentration is a more accurate index for the estimation of milk lead concentration than is whole blood lead concentration.
虽然已经确定铅会在乳汁中从母体转移至哺乳的后代，但其中涉及的生理过程和参数尚未得到充分了解。给泌乳和非泌乳的雌性小鼠静脉注射（0.2毫克/千克）或口服（2毫克/千克）放射性标记的铅，并在21天内测定血液、血浆和乳汁中的铅浓度。观察到泌乳小鼠和非泌乳小鼠在铅消除方面存在很大差异。初始母体剂量（“吸收”剂量）的很大一部分（25%）转移到了哺乳幼崽体内。发现乳汁中铅浓度与血浆中铅浓度的比值随时间几乎保持恒定。然而，同期乳汁与血液的浓度比值下降。此外，乳汁中的铅浓度超过血浆浓度约25倍，这表明存在一种生理过程使得乳汁与血浆的浓度比值很大。还观察到了类似的钙浓度比值。得出的结论是，与全血铅浓度相比，血浆铅浓度是估算乳汁铅浓度更准确的指标。
