title: Energy-dependent Mn2+ and Ca2+ uptake by the embryonic chick chorioallantoic membrane.
abstract: 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.
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001693:Biological Transport, Active; D002118:Calcium / Q000378:metabolism*; D002642:Chick Embryo; D004578:Electron Spin Resonance Spectroscopy; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005321:Extraembryonic Membranes / Q000378:metabolism*; D007700:Kinetics; D008345:Manganese / Q000378:metabolism*
chemical_list: D008345:Manganese; D002118:Calcium