684 PANTOTHENIC ACID 



b. Environmental Effects 



Spector et alP reported that the urinary and dermal excretion of panto- 

 thenic acid was greater in human subjects under hot moist conditions than 

 under comfortable conditions. Mills, ^ however, found no difference in the 

 dietary concentration of this vitamin required for maximum growth of the 

 rat at 68° F. and at 91° F. 



c. Effect of Other Nutrients 



It has long been known that the type of carbohydrate in the diet may 

 affect profoundly the requirements of rats and other animals for the B 

 vitamins. It was reported in 1926 by Fridericia^" that some rats receiving 

 uncooked rice-starch as the source of carbohydrate developed a condition 

 designated as "refection" and required no "B vitamin" in their food. Ani- 

 mals on the rice-starch diet which did not become refected spontaneously 

 developed the condition after ingestion of feces from refected ani- 

 mals (Fridericia and coworkers^^). It was also shown by Roscoe^^ that in 

 order to continue in a refected state an animal must continue to ingest his 

 own or similar feces. Morgan and coworkers^^ showed that rats receiving 

 starch as the source of carbohydrate grew well without filtrate factor and 

 that supplementation of the diet of these animals with filtrate factor con- 

 centrates improved the growth rate only slightly. 



The level of protein, also, has been shown by Nelson and coworkers to 

 affect the dietary requirement of the rat for pantothenic acid.^'*'^^ Animals 

 deficient in this vitamin receiving casein at a level of 64 % grew better and 

 survived longer than littermates maintained on a 24 % casein diet.^^ When 

 intermediate levels of casein were used, the sparing effect was proportional 

 to the protein level. ^^ When washed beef blood fibrin, which was even lower 

 in its pantothenic acid content than the casein, was used as the protein 

 component of the diet, even more pronounced differences between 64 % and 

 24 % levels of protein were seen.^^ The pantothenic acid requirement of the 

 pig has also been shown to be similarly dependent on the level of protein 

 in the diet.^^ 



Yacowitz et al?^ reported that the presence or absence of vitamin B12 in 



29 H. Spector, T. S. Hamilton, and H. H. Mitchell, /. Biol. Chem. 161, 145 (1945). 



30 L. S. Fridericia, Skand. Arch. Physiol. 2, 55 (1926). 



31 L. S. Fridericia, P. Freudenthal, S. Gudjonnsson, G. Johansen, and N. Schoubye, 

 J. Hyg. 27, 70 (1927). 



32 M. H. Roscoe, /. Hyg. 27, 103 (1927). 



33 A. F. Morgan, B. B. Cook, and H. G. Davidson, /. Nutrition 15, 27 (1938). 



34 M. M. Nelson and H. M. Evans, Proc. Soc. Exptl. Biol. Med. 60, 319 (1945). 



35 M. M. Nelson, F. van Nouhuys, and H. M. Evans, /. Nutrition 34, 189 (1947). 



36 M. M. Nelson and H. M. Evans, Proc. Soc. Exptl. Biol. Med. 66, 299 (1947). 



37 R. W. Luecke, J. A. Hoefer, and F. Thorp, Jr., /. Animal Sci. 11, 238 (1952). 



38 H. Yacowitz, L. C. Norris, and G. F. Heuser, /. Biol. Chem. 192, 141 (1951). 



