Relative levels of citric and lactic acids in certain mineralized tussues.

The citric acid and lactic acid contents of a number of mineralized tissues were estimated. Of the tissues examined the rat incisor was unique in that it was the only one in which the lactic acid content exceeded that of citric acid, the effect being largely due to the unusually low level of the latter. This observation may be related to the fact that the rat incisor is a continuously growing and metabolically active tissue. © 1963

CITRATE IN MINERALIZED TISSUES. VII. THE EFFECTS OF REHABILITATION WITH PHOSPHATE OR WITH PHOSPHATE AND VITAMIN D IN RATS PREVIOUSLY MAINTAINED ON DIETS DEFICIENT IN BOTH.

In each of two experiments fifty weanling rats were maintained on diets low in phosphorus and vitamin D for 7 weeks. Ten animals in each experiment were then killed. In Experiment 1 the remaining forty rats were transferred to a diet containing adequate phosphorus and vitamin D; in Experiment 2 the animals were transferred to a diet adequate in phosphorus but still low in vitamin D. In both experiments animals were killed at intervals during the 35-day period following transfer and the concentrations of calcium, inorganic phosphate and citrate in blood and bone were determined. When the animals were transferred to a diet adequate in phosphorus but with no added vitamin D (Experiment 2) the serum citric acid concentration fell from its initially high level to a minimum value after 16 days and then rose slightly at 35 days. The bone citric acid concentration subsided during the 35-day period. When the animals were transferred to a diet containing adequate phosphorus and vitamin D (Experiment 1) the high serum citric acid concentration again declined after 35 days, but with the difference that there was a peak value of 16 days. There was a sharp increase in bone citric acid concentration followed by a steady decline to normal after 35 days. These differences in reaction in the two experiments support the view that vitamin D has a direct action on citric acid synthesis in bone but that not all bone citric acid is formed in situ. © 1964

CITRATE IN MINERALIZED TISSUES. VI. THE EFFECTS OF DIETARY REHABILITATION WITH CALCIUM OR WITH VITAMIN D, OR WITH CALCIUM AND VITAMIN D, IN RATS PREVIOUSLY MAINTAINED ON A DIET DEFICIENT IN BOTH CALCIUM AND VITAMIN D.

Fifty weanling hooded rats were maintained for 8 weeks on a diet low in calcium and vitamin D. Similar groups were then transferred to diets adequate in calcium, or adequate in vitamin D, or sufficient in both respects. They were continued on these diets and representatives were killed at intervals during the 35 day period. The concentrations of calcium, phosphorus, and citrate in blood and bone were determined. When the deficient animals were rehabilitated with vitamin D alone, the concentration of citrate in bone was increased before that in the serum. Rehabilitation with calcium alone caused an increase in the concentration of serum citrate before any increase was observed in the bone. When the animals were transferred to a diet containing adequate supplies of calcium and vitamin D, the effects of both factors were distinguished since they occurred at different times. The implications of these results in relation to the possible function of citrate in bone are discussed. © 1963

CITRATE IN MINERALIZED TISSUES. VI. THE EFFECTS OF DIETARY REHABILITATION WITH CALCIUM OR WITH VITAMIN D, OR WITH CALCIUM AND VITAMIN D, IN RATS PREVIOUSLY MAINTAINED ON A DIET DEFICIENT IN BOTH CALCIUM AND VITAMIN D.

Fifty weanling hooded rats were maintained for 8 weeks on a diet low in calcium and vitamin D. Similar groups were then transferred to diets adequate in calcium, or adequate in vitamin D, or sufficient in both respects. They were continued on these diets and representatives were killed at intervals during the 35 day period. The concentrations of calcium, phosphorus, and citrate in blood and bone were determined. When the deficient animals were rehabilitated with vitamin D alone, the concentration of citrate in bone was increased before that in the serum. Rehabilitation with calcium alone caused an increase in the concentration of serum citrate before any increase was observed in the bone. When the animals were transferred to a diet containing adequate supplies of calcium and vitamin D, the effects of both factors were distinguished since they occurred at different times. The implications of these results in relation to the possible function of citrate in bone are discussed. © 1963

CITRATE IN MINERALIZED TISSUES. VII. THE EFFECTS OF REHABILITATION WITH PHOSPHATE OR WITH PHOSPHATE AND VITAMIN D IN RATS PREVIOUSLY MAINTAINED ON DIETS DEFICIENT IN BOTH.

In each of two experiments fifty weanling rats were maintained on diets low in phosphorus and vitamin D for 7 weeks. Ten animals in each experiment were then killed. In Experiment 1 the remaining forty rats were transferred to a diet containing adequate phosphorus and vitamin D; in Experiment 2 the animals were transferred to a diet adequate in phosphorus but still low in vitamin D. In both experiments animals were killed at intervals during the 35-day period following transfer and the concentrations of calcium, inorganic phosphate and citrate in blood and bone were determined. When the animals were transferred to a diet adequate in phosphorus but with no added vitamin D (Experiment 2) the serum citric acid concentration fell from its initially high level to a minimum value after 16 days and then rose slightly at 35 days. The bone citric acid concentration subsided during the 35-day period. When the animals were transferred to a diet containing adequate phosphorus and vitamin D (Experiment 1) the high serum citric acid concentration again declined after 35 days, but with the difference that there was a peak value of 16 days. There was a sharp increase in bone citric acid concentration followed by a steady decline to normal after 35 days. These differences in reaction in the two experiments support the view that vitamin D has a direct action on citric acid synthesis in bone but that not all bone citric acid is formed in situ. © 1964