48 P. A. Thornton 



Summary 



1. Morphological modifications by PTH have been observed in cell cultures, 

 suggesting an effect on the cell membrane: microvilli, blebbing, decreased cellular 

 adhesion, vacuolization and pinocytosis. 2. The changes in metabolism of these cells 

 effected by PTH (increased lactate production, phosphate transport and ^^P in- 

 corporation into lipid phosphorus) are similar to those observed in bone, kidney and 

 intestine. 3. Shifts of calcium from medium to cells were observed after PTH; these 

 could explain the changes in cellular adhesion. 4. An increased membrane resistance 

 was obtained in toad bladder after PTH, a finding consistent with an increased 

 calcium binding to the membrane. 5. These results also suggest that PTH, beyond and 

 above its role of increasing serum calcium, might play a further role in the distribu- 

 tion of calcium between the extracellular fluid and the cells. 



References 



BoRLE, A. B., H. T. Keutmann, and W. F. Neuman: Role of parathyroid hormone in phos- 

 phate transport across rat duodenum. Amer. J. Physiol. 204, 705 (1963). 



— , and W. F. Neumann: Effects of parathyroid hormone on HeLa cell culture. J. Cell Biol. 

 24, 316 (1965). 



— , N. Nichols, and G. Nichols, Jr.: Metabolic studies of bone in vitro. II. The metabolic 

 patterns of accretion and resorption. J. biol. Chem. 235, 1211 (1960). 



Egawa, J., and W. F. Neuman: Effects of parathyroid hormone on phosphate turnover in 

 bone and kidney. Endocrinology 72, 370 (1963). 



Sbarra, a. J., and M. L. Karnovsky: The biochemical basis of phagocytosis. I. J. biol. 

 Chem. 234, 1355 (1959). 



— — The biochemical basis of phagocytosis. II. J. biol. Chem. 235, 2224 (1960). 



Weiss, L.: Studies on cellular adhesion In tissue culture. III. Some effects of calcium. Exp. 

 Cell Res. 21, 71 (1960). 



Vitamin D-ascorbic Acid Association in Bone Metabolism 



p. A. Thornton 



Veterans Administration Hospital, Lexington, Kentucky, and the Departments of Physiology 

 and Biophysics and Medicine, University of Kentucky, Lexington, Ky., U. S. A. 



Previous results (Thornton and Brownrigg, 1961) have indicated that ascorbic 

 acid influenced the skeletal response of chicks to vitamin D3 deficiency. Turnover of 

 skeletal ''■^Ca was enhanced in vitamin D., deficient individuals in the presence of 

 ascorbic acid, suggesting a change in the bone metabolic rate. No specific role for 

 vitamin D in bone cells has been evolved; however, investigations with cartilage have 

 suggested a metabolic function in that tissue. It appears to be needed for normal 

 formation and metabolism of citric acid (Neuman and Neuman, 1958). 



Although no evidence has been presented linking ascorbic acid to bone cellular 

 metabolism, it is accepted that this compound is involved in formation of the organic 



