228 VITAMIN D GROUP 



Pappenheimer et alP have presented roentgenograms of the rear leg of a 

 ricketic rat which shows the same lack of calcification and the wide area 

 of uncalcified cartilage at the junctions of the diaphyses and epiphyses. 



6. Calcium and Phosphorus Balance 



Some of the early work on the influence of the antiricketic factor on the 

 excretion or retention of calcium and phosphorus was reported in a series 

 of publications by Hart, Steenbock, and their associates/^^ They found that 

 lactating cows and goats on a diet of grains and timothy hay had a pro- 

 nounced negative calcium balance, and frequently the balance of phos- 

 phorus was also negative. It was possible to bring the milking goats into 

 a positive calcium and phosphorus balance by giving alfalfa hay or cod 

 liver oil or by irradiating the animals with ultraviolet light. More difficulty 

 was encountered when an attempt was made to bring about a retention of 

 calcium and phosphorus in the lactating cow. The best results were ob- 

 tained with alfalfa hay, and the green plant was better than the dried hay. 

 The giving of as much as 10 ml. of cod liver oil per day caused the cows to 

 lose their appetite. 



Nicolaysen^* found that vitamin D decreased the amount of calcium ex- 

 creted in the feces of rats and increased the excretion in the urine. The ab- 

 sorption of calcium from an isolated intestinal loop was also augmented by 

 vitamin D. 



Bergeim^* has made a more detailed study of the absorption of calcium 

 and phosphorus from the intestinal tract. He found that in the normal 

 animal calcium is absorbed in the upper part of the intestines and a portion 

 of it is re-excreted in the lower part of the tract. In rickets the absorption 

 is normal, but a larger proportion is re-excreted. 



Phosphorus, on the other hand, is excreted into the upper portion of the 

 intestine and reabsorbed from the lower part. In rickets this reabsorption 

 is below normal. The administration of cod liver oil resulted in a positive 

 balance of calcium and phosphorus. Cohen and Greenberg,^^ also with the 

 rat, found only a slight increase in the intestinal absorption of radioactive 

 phosphorus, although there was a marked improvement in the deposition 

 of phosphorus in the bone when \'itamin D was administered. 



In contrast to phosphorus, Greenberg'" found a definite increase in the 



32 A. M. Pappenheimer, G. F. McCann, and T. F. Zucker, J. Exptl. Med. 35, 421 

 (1922). 



33 E. B. Hart, H. Steenbock, E. C. Teut, and G. C. Humphrey, ./. Biol. Chem. 84, 

 367 (1929). 



34 R. Nicolaysen, Biochem. J. 31, 122, 323 (1937). 



35 0. Bergeim, /. Biol. Chem. 70, 51 (1926). 



36 W. E. Cohn and D. M. Greenberg, J. Biol. Chem. 130, 625 (1939). 



37 D. M. Greenberg, J. Biol. Chem. 157, 99 (1945). 



