1988 Volume 34 Issue 1 Pages 47-54
The effects of high calcium and/or high protein diet on bone growth were examined in growing rats kept at high ambient temperature. Thirty-five Wistar strain male rats aged 45 days were divided into 5 groups; room temperature, 24°C and a normal diet (CN), 34°C and a normal diet (HN), 34°C and a high calcium diet (HCa), 34°C and a high protein diet (HPr), and, 34°C and a high calcium-protein diet (HCaPr). The animals were given the same amount of feed. On day 35 of experiment, blood and femurs were collected from all rats. Physical traits, calcium and phosphorus contents of right femur were measured. The number of chondrocyte and the thickness of epiphyseal growth plate were measured in distal epiphysis of left femur. Alkaline phosphatase activities and protein contents were measured in the homogenate of proximal epiphysis and diaphysis of left femur. Ultrafiltrable calcium concen-trations and total concentrations of calcium and phosphorus were mea-sured, in serum. None of the treatments significantly affected the elon-gation and densities of calcium and phosphorus in femur. The bone growth in width was reduced at high ambient temperature and high protein diet furthermore reduced the bone growth in width at high ambient temperature. Total calcium and phosphorus concentrations were lower in serum at high ambient temperature. Total calcium concentration in serum was increased by high calcium diet and decreased by high protein diet in hot environment, , while ultrafiltrable calcium concentration in serum tended to be higher at high temperature. Since the number of chondrocyte and the thickness of epiphyseal growth plate were greater at high ambient temperature, there was a possibility that the length of femur might become longer at high ambient temperature when the animals were kept at high ambient temperature for a longer period than in the present study.
