Armbrecht H J, Terepka A R, Gunter T E
Biochim Biophys Acta. 1976 Mar 19;426(3):547-56. doi: 10.1016/0005-2736(76)90398-9.
The chick chorioallantoic membrane is an epithelial tissue which actively transports large amounts of Ca2+ during embryonic development. In this paper Mn2+ uptake by the tissue was studied and compared to Ca2+ uptake in parallel experiments. The purpose of these experiments was to determine if Mn2+ could be used to gain more information about the Ca2+ transport system. It was found that Mn2+ uptake was reduced significantly under conditions that reduced Ca2+ uptake and that Mn2+, like Ca2+, was taken up preferentially by the ectodermal side of the tissue. Mn2+ uptake showed saturation kinetics with a Km of 0.33 MM. Mn2+ uptake was also competitively inhibited by Ca2+, and Ca2+ uptake inhibited by Mn2+. Electron microprobe studies showed that Mn2+ was localized in the ectoderm of the tissue in the same way as Ca2+. It was concluded from these studies that significant amounts of Mn2+ were accumulated by the active Ca2+ transport mechanism and that Mn2+ could be useful paramagnetic probe of divalent cation transport in this tissue.
鸡胚绒毛尿囊膜是一种上皮组织，在胚胎发育过程中能主动转运大量的Ca2+。本文研究了该组织对Mn2+的摄取，并在平行实验中将其与Ca2+摄取进行了比较。这些实验的目的是确定Mn2+是否可用于获取更多关于Ca2+转运系统的信息。结果发现，在降低Ca2+摄取的条件下，Mn2+摄取显著减少，并且与Ca2+一样，Mn2+优先被组织的外胚层一侧摄取。Mn2+摄取呈现饱和动力学，Km为0.33毫摩尔。Mn2+摄取也受到Ca2+的竞争性抑制，而Ca2+摄取受到Mn2+的抑制。电子微探针研究表明，Mn2+与Ca2+一样，定位在组织的外胚层中。从这些研究得出的结论是，活性Ca2+转运机制积累了大量的Mn2+，并且Mn2+可能是该组织中二价阳离子转运的有用顺磁探针。
