XI. REQUIREMENTS AND FACTORS INFLUENCING THEM 691 



the intake, and as the intake was increased the total excretion increased. 

 The effect of test doses of various magnitudes confirms this observation, 

 and as was shown by Rubin et al}^ the dose response relationship is quite 

 constant — ^the greater the test dose, the greater the excretion. 



The question arises as to what use one can make of the data on the 

 excretion of pantothenic acid in estimating the daily requirement. The 

 fecal excretion remains fairly constant on different intakes, and it is the 

 urinary excretion which reflects the daily intake. If one assumes that the 

 amount of the vitamin excreted in the urine represents an excess of the 

 bodily need, then subtraction of the amount excreted daily from the 

 amount ingested might be considered as the amount required daily in a 

 normal, well-nourished subject. The average daily excretion (3.7 mg. in the 

 urine and 1.0 mg. in the feces) subtracted from an approximate average 

 intake of 10.4 mg., would leave approximately 6.4 mg. as the daily require- 

 ment. 



3. Approximate Pantothenic Acid Requirement of Man as Based on 

 THE Known Requirement of the Experimental Animal 



In all experimental studies in animals, the physiological state of the 

 animal influences its requirement for pantothenic acid. The requirement 

 of the growing animal is much greater than that of the adult. Similarly, 

 stress increases the animal's requirement for pantothenate. As an example 

 of this, it was reported by Lotspeich'^^ that symptoms of pantothenic acid 

 deficiency, which are very slow to appear in the adult rat on a deficient 

 diet, can be induced fairly rapidly if the animal is given injections of an 

 anterior pituitary hormone. Other forms of stress, such as pregnancy and 

 hyperthyroidism, will also increase the requirement for this vitamin.'^^- '^^ 



The pantothenic acid requirement for the rat decreases from about 2.5 

 mg. per kilogram of body weight daily at weaning to approach 0.1 mg. per 

 kilogram for the adult rat.^® More than 3 mg. is required daily by the 

 weanling mouse,''^ whereas the young dog requires only 0.1 mg.'^^ Since 

 adult dogs survive much longer on diets deficient in pantothenic acid than 

 do pups, the adult reciuirement is thought to be less than 0.1 mg. per kilo- 

 gram. I am indebted to Dr. Mary E. Dumm for the graphic summary of 

 these data, shown in Fig. 11, in which the requirement of pantothenic acid 



" W. D. Lotspeich, Froc. Soc. Exptl. Biol. Med. 73, 85 (1950). 

 '^ J. Boisselot, Arch.fran^. pediat. 6, 225 (1949). 



75 V. A. Drill and R. Overman, Am. J. Physiol. 135, 474 (1942). 



76 K. Unna and G. V. Richards, /. Nutrition 23, 545 (1942). 



" J. G. Sandza and L. R. Cerecedo, /. Nxdrition 21, 609 (1941). 



78 A. E. Schaefer, J. M. McKibbin, and C. A. Elvehjem. J. Biol. Chem. 143, 321 

 (1942). 



