title: Influence of age and magnesium on calcium metabolism in rats.
abstract: This study evaluates the effect of dietary magnesium concentration on calcium metabolism in rats of differing ages. Young (3 wk) and old (18 mo) Fischer 344 rats were fed the AIN-76A diet modified to contain either low (218 mg/kg) or adequate (419 mg/kg) Mg for 4 wk. Some rats subsequently underwent a metabolic balance study (12 d duration). Other rats were gavaged with approximately 220 KBq (6 microCi) of 47Ca; daily fecal and urine collections were made and periodic whole body radioactivity determined. Femurs were removed and analyzed. Calcium retention and balance were not affected by Mg in young rats. In old rats low Mg intake increased apparent Ca balance. Young rats retained about 3.25 times more of the original dose of 47Ca than did old rats. Young rats retained more 47Ca in the femur than did old rats; Mg intake had little effect. Aging accelerated Ca turnover rate, and whole body retention data suggest that adequate Mg does not significantly reduce Ca turnover.
authors.affiliation: Department of Human Nutrition and Foods, University of Missouri, Columbia 65211.
authors.forename: S T
authors.initials: ST
authors.lastname: McElroy
authors.forename: J E
authors.initials: JE
authors.lastname: Link
authors.forename: R P
authors.initials: RP
authors.lastname: Dowdy
authors.forename: K R
authors.initials: KR
authors.lastname: Zinn
authors.forename: M R
authors.initials: MR
authors.lastname: Ellersieck
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000378:metabolism* / Q000652:urine; D002132:Calcium Radioisotopes; D004032:Diet; D005243:Feces / Q000737:chemistry; D006207:Half-Life; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology*; D008275:Magnesium Deficiency / Q000378:metabolism; D008297:Male; D011897:Random Allocation; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D002132:Calcium Radioisotopes; D008274:Magnesium; D002118:Calcium