Effects of dietary NaCl supplementation on bone synthesis of hydroxyproline, urinary hydroxyproline excretion and bone 45Ca uptake in the rat.
High sodium chloride intakes are regarded as a risk factor for osteoporosis because they increase the obligatory urinary calcium loss and stimulate parathyroid activity. Sodium chloride loads induce osteopenia in the rat. The effect could be due to a decrease in bone formation or a rise in bone resorption. Two experiments were undertaken to study the effects of dietary NaCl supplementation on 3H-hydroxyproline synthesis and 45Ca uptake in femoral bone. Salt-treated rats excreted 1.7 times more total urinary hydroxyproline (P less than 0.001) and 2.1 times more recently labelled 3H-hydroxyproline than controls (P less than 0.02) but they did not accumulate less 3H-hydroxyproline or less 45Ca in their bones than controls. These results indicate that salt-mediated osteopenia is due to an increase in bone resorption, rather than to a decrease in bone formation.
Goulding
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Department of Medicine, University of Otago Medical School, Dunedin, New Zealand.
Gold
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E
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001851:Bone Diseases, Metabolic / Q000209:etiology; D001862:Bone Resorption / Q000187:drug effects; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D005260:Female; D006909:Hydroxyproline / Q000096:biosynthesis* / Q000652:urine; D010012:Osteogenesis / Q000187:drug effects; D051381:Rats; D012982:Sodium, Dietary / Q000008:administration & dosage / Q000009:adverse effects*
D012982:Sodium, Dietary; D006909:Hydroxyproline; D002118:Calcium