Renal actions of vitamin D in D-deficient rats
Costanzo, L.S.; Sheehe, P.R.; Weiner, I.M.
American Journal of Physiology 226(6): 1490-1495
1974
ISSN/ISBN: 0002-9513 PMID: 4834008 Document Number: 81837
Sprague-Dawley male rats from weaning were kept away from daylight and given a diet lacking vitamin D and with Ca 0.44 and P 0.05%. Rats so fed maintained normal serum Ca as long as they were fed, but when food was withheld for 12 h they became hypocalcaemic. They ceased to gain weight after about 35 days, when they weighed about 150 g; controls given the same diet with 75 IU ergocalciferol every 3 days reached a mean weight of 177 g at 35 days and continued to grow thereafter. Rats described as vitamin D repleted had been deprived and then given one dose of 100 IU cholecalciferol by mouth 48 h before study. Thyroids and parathyroids were destroyed by electrocautery immediately before experiments. Infusions were given into a femoral vein and blood samples were taken from a femoral artery; both ureters were catheterised near the renal pelvis. Ca clearance ratios at comparable Na clearance ratios were significantly lower in vitamin D repleted than in deprived rats over the range of Na excretion obtained. There was no phosphate excretion in repleted rats at filtered loads as high as 5 mu mol/min. Deficient rats excreted significant amounts of phosphate, especially at filtered loads above 2 mu mol/min. An appendix describes the statistical methods employed.