A characterization of vitamin D-independent intestinal calcium absorption in the osteopetrotic (op/op) mouse.
Previous work in our laboratory showed that the osteopetrotic (op/op) mouse possesses a vitamin D-independent mechanism of intestinal calcium absorption. This study was performed in an effort to further characterize the mechanism. The vitamin D-deficient op/op mouse absorbed calcium faster than either a vitamin D-deficient or 1, 25-dihydroxyvitamin D(3)-supplemented wild-type mouse. This increased rate of absorption was not found at concentrations of calcium that result in diffusional calcium absorption. Thus, vitamin D-deficient op/op mice had intestinal calcium absorption similar to that of vitamin D-deficient wild-type littermates when increasing levels of calcium were administered. Also, mRNA and protein levels of calbindin-D9k were similar in vitamin D-deficient wild-type and op/op mice as well as in wild-type and op/op mice treated with 1, 25-dihydroxyvitamin D(3). Therefore, the mechanism of vitamin D-independent intestinal calcium absorption in the op/op mouse is distinct from vitamin D-dependent intestinal calcium absorption.
McCary
L C
LC
Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA.
Staun
M
M
DeLuca
H F
HF
D000818:Animals; D002117:Calcitriol / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism*; D017136:Ion Transport; D051379:Mice; D008820:Mice, Obese; D010022:Osteopetrosis / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000378:metabolism*
D002120:Calcium Channel Agonists; D002117:Calcitriol; D002118:Calcium