Increased urinary calcium excretion potentiates bone turnover in oophorectomized rats.
The differential effects of sodium-induced renal hypercalciuria on the biochemical markers of bone metabolism and calcium homeostasis were studied in oophorectomized (Oophx) and sham-operated rats. The rats consuming a normal (0.4%) calcium semisynthetic diet were randomly allocated to either 0, 0.4, 0.6, 0.9, or 1.25% NaCl in their drinking water for 7 days. At that time fasting blood and urine specimens were collected and analyzed for bone-related biochemical variables. The urinary calcium/creatinine ratio was increased with increasing urinary sodium (p < 0.01) in both sham and Oophx animals. The hydroxyproline/creatinine ratio was elevated as a result of Oophx (p < 0.001) and was raised with increasing urinary sodium in both sham (p = 0.012) and Oophx animals (p = 0.007). Serum osteocalcin and alkaline phosphatase were elevated in Oophx rats (p < 0.02). While serum osteocalcin was raised with increasing urinary sodium in Oophx rats (p = 0.035), there was no effect on osteocalcin levels in sham-operated rats. This study demonstrates that sodium-induced renal hypercalciuria potentiates bone turnover in Oophx rats as compared with ovary-intact rats and indicates important implications for the effect of dietary salt on bone turnover with ovarian hormone deficiency.
Mason
R A
RA
Department of Physiology, University of Adelaide, Australia.
Morris
H A
HA
D000818:Animals; D001862:Bone Resorption / Q000209:etiology*; D002118:Calcium / Q000652:urine*; D004967:Estrogens / Q000172:deficiency*; D005260:Female; D010052:Ovariectomy; D010281:Parathyroid Hormone / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012982:Sodium, Dietary / Q000008:administration & dosage*
D004967:Estrogens; D010281:Parathyroid Hormone; D012982:Sodium, Dietary; D002118:Calcium