DENERVATION ATROPHY OF BONE AND MUSCLE. AN EXAMINATION OF THE EFFECT OF CHOLINE AND SOME FURTHER OBSERVATIONS ON THE METABOLISM OF PHOSPHORYLCHOLINE AND DEPOSITION OF P32 IN BONE

Abstract

The daily parenteral adm. of choline chloride had no significant effect on the course of denervation atrophy of the humerus or of the flexor muscles of the forelimbs in the rat. Following unilateral brachial section in [male] rats weighing 150-250 g., flexor muscles of the denervated forelimb weighed 56-59% less than the respective control limbs 24 days after denervation. However, no net loss of muscle mass occurred in the denervated limb after the time of operation; the apparent difference was explained by normal growth in the control limb. Hypertrophic growth in the control limb was not apparent. In the same animals, the humerus continued to gain in mass after the time of operation, although this accretion was slower than normal. The unoperated control femur gave no evidence of hypertrophic growth. The 24 hr. uptake of P32 by bone ash is the same on an ash wt. basis in normal and atrophic limbs. By far the greatest uptake must be by ionic exchange since the appearance of P32 in the femur does not parallel the accretion rate of the bone. The P of trace-doses of Ca phosphorylcholine does not enter bone ash preferentially to inorganic phosphate.