A simple technique for the measurement of unidirectional calcium influx at the mucosal surface of organ-cultured embryonic chick duodenum.
Unidirectional calcium influx can be measured by application of a filter paper blotter saturated with a 45Ca-labeled buffer solution to the mucosal surfaces of slit-open embryonic chick duodena which had been cultured mucosal side up on stainless-steel grids. The results obtained with this simple technique support the contention of a direct involvement of a vitamin D-induced calcium-binding protein in the transport of calcium across the mucosal surface. Permeability and inulin space measurements validate the method for measurement of calcium influx at initial velocity and obviate concern for "unstirred layer" effects. Kinetic analyses indicate a two step influx process, one saturable at about 5 mM calcium and the other essentially unsaturable.
Department of Physical Biology/Section of Physiology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14853, USA.
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Corradino
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002642:Chick Embryo; D004386:Duodenum / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism; D017136:Ion Transport; D007700:Kinetics; D008722:Methods; D009924:Organ Culture Techniques; D064030:S100 Calcium Binding Protein G / Q000378:metabolism
D002132:Calcium Radioisotopes; D064030:S100 Calcium Binding Protein G; D002118:Calcium