title: Effects of diet calcium and 1,25-dihydroxyvitamin D3 on colon calcium active transport.
abstract: Unidirectional fluxes of calcium were studied in the absence of electrochemical gradients across rat descending colon segments in vitro. Dietary calcium restriction and 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3]enhanced absorption by increasing the mucosal-to-serosal fluxes, whereas secretory (serosal-to-mucosal) fluxes were unchanged. Low-calcium diet also stimulated calcium uptake by everted gut sac segments of ascending as well as descending colon, whereas transverse colon was unresponsive. These results show that the colon is a target organ for 1,25-(OH)2D3 and demonstrate the participation of colon in the intestinal adaptation to calcium deprivation.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000172:deficiency / Q000378:metabolism*; D002136:Calcium, Dietary / Q000494:pharmacology*; D003106:Colon / Q000378:metabolism*; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D006887:Hydroxycholecalciferols / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats
chemical_list: D002136:Calcium, Dietary; D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D002118:Calcium