Effects Of Dietary Phosphorus Research Articles

Effects of Dietary Phosphorus and Calcium Level on Performance, Bone Mineralization and Carcass Characteristics of Swine

Effects of Dietary Phosphorus and Calcium Level on Performance, Bone Mineralization and Carcass Characteristics of Swine

The effect of dietary phosphorus on the intermediary metabolism of epiphyseal cartilage from rachitic rats.

1.1. Rickets was produced in weanling rats with a diet low in inorganic phosphate and vitamin D. The addition of inorganic phosphate to the diet healed the rickets morphologically, decreased the water and increased the mineral content of teh tibial epiphyses. The concentration of DNA relative to the wet weight was greater in the normal compared to the rachitic epiphyses.2.2. Slices of tibial epiphyses from rachitic rats incubated aerobically in vitro produced more labeled and unlabeled lactate from [14C]glucose and [14C]pyruvate than those from rats on standard diets. The ration of 14CO2/[14C]lactate formed was significantly higher in the slices from the normal rats. Addition of phosphate but not vitamin D to the diet of the rachitis rats reversed these changes towards normal.3.3. Addition of pyruvate to the incubation medium stimulated production of 14CO2 from [i-14C]glucose to a greater extent in the rachitic than in the normal rats.4.4. Lactate dehydrogenase (EC 1.1.1.27) activity was higher in extracts of teh epiphyseal cartilage from the rachitis rats as compared to the normal.5.5. The alteration in the regulation of aerobic glycolysis in the rachitis epiphyseal cartilage probably occurs at several different sites. 1. Rickets was produced in weanling rats with a diet low in inorganic phosphate and vitamin D. The addition of inorganic phosphate to the diet healed the rickets morphologically, decreased the water and increased the mineral content of teh tibial epiphyses. The concentration of DNA relative to the wet weight was greater in the normal compared to the rachitic epiphyses. 2. Slices of tibial epiphyses from rachitic rats incubated aerobically in vitro produced more labeled and unlabeled lactate from [14C]glucose and [14C]pyruvate than those from rats on standard diets. The ration of 14CO2/[14C]lactate formed was significantly higher in the slices from the normal rats. Addition of phosphate but not vitamin D to the diet of the rachitis rats reversed these changes towards normal. 3. Addition of pyruvate to the incubation medium stimulated production of 14CO2 from [i-14C]glucose to a greater extent in the rachitic than in the normal rats. 4. Lactate dehydrogenase (EC 1.1.1.27) activity was higher in extracts of teh epiphyseal cartilage from the rachitis rats as compared to the normal. 5. The alteration in the regulation of aerobic glycolysis in the rachitis epiphyseal cartilage probably occurs at several different sites.

THE EFFECT OF DIETARY PHOSPHORUS ON THE METABOLISM OF CALCIUM AND STRONTIUM IN THE RAT.

SummaryAn investigation has been made of the way in which changes in dietary phosphorus within the physiological range influence the comparative metabolism of calcium and strontium in the rat. Radioactive calcium and strontium were used as tracers.The absorption of both calcium and strontium after oral administration was dependent on the phosphorus level in the diet, but not to the same degree. The skeletal ratio 85Sr/47Ca decreased by some 40 per cent as the dietary phosphorus was increased from 0·5 to 1·3 g per cent.After intraperitoneal injection of radioactive calcium and strontium, the skeletal retention of 85Sr was about 25 per cent more on a diet containing 1·3 per cent phosphorus than on a diet containing 0·5 per cent phosphorus. Skeletal retention of calcium varied little.It is concluded that renal discrimination against strontium as well as intestinal absorption of calcium and strontium were affected by the phosphorus content of the diet, but in opposite directions.