EFFECT ON VARIOUS PHYSIOLOGIC PROCESSES 667 



to be the key substance, and a decrease in its concentration was always a 

 reflection of an increasing deficiency of phosphorus in the rats. Guest and 

 Rapoport-^- suggested that the "rapid increase in the concentration of 

 diphosphoglycerate in the blood cells following any of the procedures 

 which induced heahng appeared to be a sign of rapid mobilization of phos- 

 phorus in the bod}^ and of the a\'ailability of such phosphorus for transport 

 to the calcifying bone." This theory is a most attractive one, and while it 

 has not been confirmed by other workers, it has not been refuted. 



According to Nicolaysen and Eeg-Larsen,^ other reports of changes in 

 the phosphate fraction are indecisive. This is true of the results of the 

 Finnish workers, Raiha et al}^^ and Peitsara,-^"* who recorded the presence 

 of a difficultly hj'drolyzable acid-soluble phosphate fraction in the muscles 

 of rachitic dogs which increased further during exercise. In the case of 

 normal dogs, this fraction decreased. The results of Cohn and Green- 

 j5Pj.g295 Q^Q almost unconfirmed. They concluded that vitamin D in- 

 creases the conversion of organic phosphorus to the inorganic form in the 

 bone. The data of Underwood and co-workers, -^^ who believed that the 

 inorganic phosphorus was increased in the blood of fasted rachitic rats 

 which had been given A'itamin D, are also open to question. 



One possible explanation for the action of vitamin D, already suggested 

 for phosphatase in general, is that its effect may be hmited to kidney phos- 

 phatase. Thus, Zetterstrom^^" observed that phosphorylated vitamin 

 D2 exerted an appreciable effect upon the activity of purefied kidney phos- 

 phatase. Later, the same worker-^^ postulated that the phosphorylated 

 \dtamin D stimulated the oxygen uptake of the kidney mitochondria. 

 However, the data of Pardee and Potter^^^ do not agree quantitatively 

 \dt\i those of Zetterstrom,-^* while Eeg-Larsen and Gran (in unpublished 

 work cited b}^ Nicolaysen and Eeg-Larsen)^ noted an identical O2 uptake 

 in kidney homogenates from normal and from rachitic rats. 



a. Vitamin D and Phosphate Resorption in the Kidneys. One of the 

 fairh' recent suggestions to account for the changes in phosphate metabo- 

 lism in rickets is that the diminished plasma phosphate results not only 

 from the dej&cient absorption in the intestine, but also from the unusually 



2" G. IVI. Guest and S. Rapoport, Physiol. Revs., 21, 410-437 (1941). 

 "3 C. E. Raiha, E. Helske, H. Peitsara, and E. Vehniainen, Acta Paediat., 19, 335-369 

 (1937). 



"" H. Peitsara, Acta Paediat., 31, Suppl. 3, 1-244 (1944). 



"s W. E. Cohn and D. M. Greenberg, /. Biol. Chem., 130, 625-634 (1939). 



"« E. Underwood, S. Fisch, and H. C. Hodge, Am. J. PhijsioL, 166, 387-393 (1951 ). 



2" R. Zetterstrom, Nature, 167, 409-140 (1951). 



"8 R. Zetterstrom, Acta Chem. Scand., 5, 343-352 (1951). 



"9 A. B. Pardee and V. R. Potter, /. Biol. Chem., ISl, 739-753 (1949). 



