Journal ArticleDOI
1α-Hydroxyvitamin D2 is Less Toxic than 1α-Hydroxyvitamin D3 in the Rat
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TLDR
The results suggest that 1 α-hydroxyvitamin D2 might represent a therapeutically Superior compound and is between 5 and 15 times less toxic than 1α-Hydroxyv vitamin D3.Abstract:
An LD50 of 0.2 mg/kg body wt has been determined for 1 alpha-hydroxyvitamin D3 in the rat. In comparison, the LD50 for 1 alpha-hydroxyvitamin D2 is between 3.5 and 6.5 mg/kg. In terms of chronic toxicity, 1 alpha-hydroxyvitamin D3 at a dose of 5 micrograms/kg/day causes death of one-half the animals in a 4-week period. On the other hand, 20 micrograms/kg/day of 1 alpha-hydroxyvitamin D2 is required to induce similar toxicity. The body weight record and renal calcium accumulation during chronic treatment support the above conclusion. It therefore appears that 1 alpha-hydroxyvitamin D2 is between 5 and 15 times less toxic than 1 alpha-hydroxyvitamin D3. This surprising result prompted a reexamination of the relative biological activity of 1 alpha-hydroxyvitamin D2 and 1 alpha-hydroxyvitamin D3. Both compounds are equally potent in the stimulation of intestinal calcium transport, bone calcium mobilization, in the elevation of serum phosphorus, and in the healing of rickets in the rat. The reason for lower toxicity of 1 alpha-hydroxyvitamin D2 is unknown. The results suggest that 1 alpha-hydroxyvitamin D2 might represent a therapeutically superior compound.read more
Citations
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References
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Vitamin D: Recent Advances
TL;DR: Autoradiography has shown specific nuclear localization of 1,25-(OH)2D3 in target organs prior to initiation of mechanism of action, suggesting the possibility that vitamin D carries out subtle functions previously unappreciated.
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Influence of sodium on calcium transport by the rat small intestine.
David L. Martin,Hector F. DeLuca +1 more
TL;DR: It is proposed that the changes observed in the transmural potential due to substitution of mannitol or choline chloride for sodium chloride may also occur in vivo and thereby cause the increase in calcium absorption observed after dietary administration of lactose and similar compounds.
Journal ArticleDOI
Role of 1,25-Dihydroxyvitamin D3 in Maintaining Serum Phosphorus and Curing Rickets
Y. Tanaka,H. F. Deluca +1 more
TL;DR: It is suggested that 1,25-dihydroxyvitamin D(3) cures rickets in rats by increasing the concentration of serum phosphorus rather than by increasing serum calcium concentration and calcium absorption.
Journal ArticleDOI
Metabolism of vitamin D2 and vitamin D3 in the rachitic chick
TL;DR: The largest fraction of the 3 H dose from the vitamin D 3 was found in bone, blood, muscle, and liver, but the highest concentration of radioactivity was finding in bone cells and intestinal mucosa.