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Dahl salt-sensitive rats develop hypovitaminosis D and hyperparathyroidism when fed a standard dietThe Dahl salt-sensitive rat (S), a model for salt-sensitive hypertension, excretes protein-bound 25-hydroxyvitamin D (25-OHD) into urine when fed a low salt diet. Urinary 25-OHD increases during high salt intake. We tested the hypothesis that continuous loss of 25-OHD into urine would result in low plasma 25-OHD concentration in mature S rats raised on a standard diet. Dahl S and salt-resistant (R) male rats were raised to maturity (12-month-old) on a commercial rat diet (1% salt) and switched to 0.3% (low) or 2% (high) salt diets 3 weeks before euthanasia. Urine (24 h) was collected at the end of the dietary treatments. Urinary 25-OHD and urinary 25-OHD binding activity of S rats were three times that of R rats, resulting in lower plasma 25-OHD and 24,25-dihydroxyvitamin D concentrations in S rats than in R rats (P < 0.001). Plasma parathyroid hormone concentrations of S rats were twice that of R rats. S rats fed 2% salt had higher plasma 1,25-dihydroxyvitamin D concentrations than those fed 0.3% salt (P = 0.002). S rats excreted more calcium into urine than R rats (P < 0.001) and did not exhibit the expected calciuric response to salt. Proteinuria of the S rats was three times that of the R rats, suggesting kidney damage in the S rats. Low plasma 25-OHD and 24,25-dihydroxyvitamin D and high plasma 1,25-dihydroxyvitamin D and PTH concentrations seen in the mature S rats have also been reported for elderly patients with low-renin (salt-induced) hypertension. An implication of this study is that low vitamin D status may occur with age in salt-sensitive individuals, even when salt intake is normal.
Document ID
20050232542
Document Type
Reprint (Version printed in journal)
Authors
Thierry-Palmer, Myrtle (Morehouse School of Medicine Atlanta, GA 30310-1495, United States)
Cephas, Stacy
Sayavongsa, Phouyong
Doherty, Akins
Arnaud, Sara B.
Date Acquired
August 23, 2013
Publication Date
April 1, 2005
Publication Information
Publication: Bone
Volume: 36
Issue: 4
ISSN: 8756-3282
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NCC9-112
CONTRACT_GRANT: RR03034
CONTRACT_GRANT: NAG2-1381
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Regulatory Physiology
Non-NASA Center