Mykkänen H M, Wasserman R H
J Nutr. 1981 Oct;111(10):1757-65. doi: 10.1093/jn/111.10.1757.
The present study was designed to investigate, in more detail, the mechanism of lead transport by the gastrointestinal tract and particularly the similarities or dissimilarities between lead and calcium in this process. The absorption of these metals was determined in 3-week-old white Leghorn cockerels, raised on a commercial diet or special diets, using an in vivo ligated loop procedure. The dose administered into the loop usually contained 0.5 microCi 203Pb (and/or 0.1 microCi 47Ca), 0.01 mM lead acetate (and/or 1 mM CaCl2) in 0.5 ml of 0.15 M NaCl, pH 6.5. It was shown that lead is rapidly taken up by the intestinal tissue, and only slowly transferred into the circulation whereas calcium, also accumulated rapidly by the tissue, is rapidly released from the tissue in the serosal direction. The absorption processes of these cations show similar responses to various experimental conditions (low calcium intake, age of the animal, pH of the dosing solution). However, increasing luminal stable lead concentration from 0.01 to 1 mM Pb, significantly reduced the percentage of radiolead absorbed, but did not inhibit the absorption of radiocalcium, Also, luminal Ca (0-25 mM) did not significantly affect the absorption of 203Pb. These data imply that, in spite of the similarities in the response of the lead and calcium absorptive processes to various treatments, there is no direct interaction between these cations in the intestine of the chick.
本研究旨在更详细地探究胃肠道对铅的转运机制，尤其是在此过程中铅与钙之间的异同。使用体内结扎肠袢法，在以商业饲料或特殊饲料饲养的3周龄白来航公鸡中测定这些金属的吸收情况。注入肠袢的剂量通常在0.5 ml pH 6.5的0.15 M NaCl中含有0.5微居里203Pb（和/或0.1微居里47Ca）、0.01 mM醋酸铅（和/或1 mM CaCl2）。结果表明，铅被肠道组织迅速摄取，然后缓慢转移到循环中，而钙虽然也被组织迅速积累，但却迅速从组织向浆膜方向释放。这些阳离子的吸收过程对各种实验条件（低钙摄入、动物年龄、给药溶液的pH值）表现出相似的反应。然而，将腔内稳定铅浓度从0.01 mM提高到1 mM Pb，显著降低了放射性铅的吸收百分比，但并未抑制放射性钙的吸收。此外，腔内钙（0 - 25 mM）对203Pb的吸收没有显著影响。这些数据表明，尽管铅和钙的吸收过程对各种处理的反应存在相似性，但在雏鸡肠道中这些阳离子之间不存在直接相互作用。
