title: Glucose 1-phosphate increases active transport of calcium in intestine.
abstract: Active calcium transport in intestine is essential for serum calcium homeostasis as well as for bone formation. It is well recognized that vitamin D is a major, if not sole, stimulator of intestinal calcium transport activity in mammals. Besides vitamin D, endogenous glucose 1-phosphate (G1P) affects calcium transport activity in some microorganisms. In this study, we investigated whether G1P affects intestinal calcium transport activity in mammals as well. Of several glycolytic intermediates, G1P was the sole sugar compound in stimulating intestinal calcium uptake in Caco-2 cells. G1P stimulated net calcium influx and expression of calbindin D9K protein in rat intestine, through an active transport mechanism. Calcium uptake in G1P-supplemented rats was greater than that in the control rats fed a diet containing adequate vitamin D3. Bone mineral density (BMD) of aged rat femoral metaphysis and diaphysis was also increased by feeding the G1P diet. G1P did not affect serum levels of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] at all. These results suggest that exogenously applied G1P stimulates active transport of calcium in intestine, independent of vitamin D, leading to an increase of BMD.
authors.affiliation: Biological Science Laboratories, Kao Corporation, 2606 Akabane, Ichikaimachi, Haga, Tochigi 321-3497, Japan.
authors.forename: Hidetake
authors.initials: H
authors.lastname: Fujinaka
authors.forename: Junji
authors.initials: J
authors.lastname: Nakamura
authors.forename: Hisataka
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Minoru
authors.initials: M
authors.lastname: Takizawa
authors.forename: Daiki
authors.initials: D
authors.lastname: Murase
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tokimitsu
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Suda
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects; D018938:Caco-2 Cells; D002117:Calcitriol / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D019587:Dietary Supplements; D005958:Glucosephosphates / Q000494:pharmacology*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D017136:Ion Transport / Q000187:drug effects; D010012:Osteogenesis / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014807:Vitamin D / Q000378:metabolism
chemical_list: D005958:Glucosephosphates; D014807:Vitamin D; C031590:glucose-1-phosphate; D002117:Calcitriol; D002118:Calcium