Bone mineral density in spontaneous hypertension: Differential effects of dietary calcium and sodium

J. A. Metz, N. Karanja, E. W. Young, C. D. Morris, D. A. McCarron

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

Dietary calcium and sodium have been postulated to modify both bone mineral status and blood pressure regulation in humans and animals. The spontaneously hypertensive rat (SHR) manifests several defects in calcium metabolism that may contribute to its hypertesion. Blood pressure and bone mineral status were measured in SHR and normotensive Wistar-Kyoto rats (WKY) as a marker of whole animal calcium metabolism. In addition, the effect of alterations in dietary calcium and sodium on bone status were examined. At 6 weeks of age, seven male SHR and seven male WKY were placed on a control diet. At the same age, 28 SHR and 28 WKY were randomized to four diets containing either 2.0% or 0.1% calcium and 1.0% or 0.25% sodium. Four markers of bone mineral status were analyzed: bone density measured by direct photon absorptiometry, and total bone calcium, phosphorus, and magnesium content measured by atomic absorption spectrophotometry. The SHR exhibited significantly lower levels (p < 0.001) of bone density and bone magnesium content that the WKY, whereas bone phosphorus and calcium did not differ between the two strains. The 2.0% calcium diets resulted in increased bone density and bone calcium content, and lower bone magnesium in both strains. The 1.0% sodium diets were associated with decreased bone density in the SHR, but not in the WKY. These findings identify another indicator of disturbed calcium metabolism in the SHR that may be related to impaired renal calcium handling. They are consistent with previously reported reductions in renal calcium reabsorption and decreased intestinal calcium transport in older SHR.

Original languageEnglish (US)
Pages (from-to)225-230
Number of pages6
JournalAmerican Journal of the Medical Sciences
Volume300
Issue number4
DOIs
StatePublished - Jan 1 1990

Keywords

  • SHR
  • bone density
  • dietary calcium
  • dietary sodium
  • hypertension

ASJC Scopus subject areas

  • Medicine(all)

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