Metabolic Activities of Vitamin D in Animals

Abstract

Concerning the enzymatic role of water-soluble vitamins many investigations have been published, but few papers are available on the mechanism of the action influencing lipid-soluble vitamins.Our recent interest in the biochemistry of lipid -soluble vitamins is an outgrowth of a curiosity about the correlation between vit amin D and sulfate metabolism.It was early reported by the present authors on the bioassay of vitamin D with rats fed on sterol-free synthetic diets and it was confirmed that no influence of vitamin B12 on the degree of healing in vitamin ID-deficient rats was observed (1).Thereafter many papers have been published on metabolic function of vitamin D, e.g., relation to calcium and phosphorus metabolism, relation to citrate metab olism and other metabolic relationships.Sano (2) summarized his researches on the rickets in Japan, e.g., thiamine and pyruvate levels in rachitic children, ribo flavin levels in blood and organs of experimental rachitic rabbits, phosphorus metab olism in young normal and rachitic rats, serum citrate levels in rachitic children and healing effect of cortisone on rachitic children. Keane et al. (3) reported that vitamin D markedly increased the absorption and retention of Ca45 given orally to chicks but no effect of the intramuscularly injected Ca45 was observed.It was concluded that the effect of vitamin D on calcium metabolism was primarily due to the absorption from the intestinal tract. Gershoff and Hegsted (4) fed diets containing various Ca/P ratios to chiks and found that the ratios had no significant effect on the intestinal absorption of Ca45 if an adequate amount of vitamin D was present.Otherwise, the calcium absorption was inverse ly proportional to Ca/P ratios.Cramer and Steenbock (5) found that the rise in calcium intake in the presence of vitamin D changed the negative calcium balance induced in rats by a low-phosphorus diet to a positive one.The relationship between vitamin D and citrate metabolism at the enzymatic level were investigated by DeLuca et al . (6). Addition of the vitamin to rachito genic or nonrachitogenic diets reduced the oxidation of citrate by kidney homo genates or mitochondria, but no effect was found on the oxidation of other Krebs cycle intermediates . These findings were presumed by the authors to account for 121

Growth Stimulating Activities of Vitamin-Dependent Enzymes in Fresh Liver for Rainbow Trout Fingerlings

“…Further experiments were repeated in our laboratory for elucidation of his vitaminological consideration Halver's interpretation for the high contents of vitamins in liver but contrary to his proposal, the present authors have realized that the total contents of vitamins in the liver were extremely low, as low as one tenth of Halver's synthetic vitamin mixture (4)(5)(6).…”

Fat-Soluble Vitamins

“…\Vith out providing definite evidence, a few recent publications indicate this may be the case. Experiments on sa5-sulfate incorporation in diet suggest that an intimate correlation between vitamin D and sulfur metaholism exists (75). By measuring free amino acid in rachitic epiphyseal cartilage of albino rats, an influence on the concentrations of serine, glycine, glutamic acid, and threonine during healing induced by vitamin D was observed (76).…”

Antirachitic Potency of Vitamin D Sulfate in Human Milk

“…Biochemistry and Nutrition , In the forgoing papers, the authors have reported the relation between vitamin D and active sulfate metabolism (1)(2)(3)(4), and the isolation of vitamin D sulfate from mammalian milk (5). Further tests for the antirachitic potency of human milk (containing 780I.U.…”