250 FKANK A. 



Influence on Muscular Activity. A number of observations point to 

 a close relationship between the suprarenals and muscular activity. First 

 of all the muscular weakness of suprarenal insufficiency suggests an in- 

 timacy between the two tissues. 



After intense prolonged muscular activity the vacuolization of the 

 suprarenals (Bernard and Bigart, Bardier and /Bonne) and the disap- 

 pearance of the lipoid-cholesterol bodies from the cortex (Laignel- 

 Lavastine) indicate exhaustion of these glands. 



Furthermore, Elliott and Tuckett have found that the size of the 

 suprarenals increases with the development of the muscles. In this con- 

 nection the observations of Watson (b) are very important. He noticed a 

 marked difference between wild and tame rats in the percentage of the 

 suprarenal to body weight. The average percentage weight for young- 

 tame rats was found to be 0.035 while that for young wild rats of similar 

 weight 0.066. The difference is even greater in adults, the percentage 

 weight averaging 0.019 for tame animals and 0.052 for wild. It should 

 be noticed also that the percentage weight decreases much less in wild 

 than in tame rats as the animals mature. This suggests that as the tame 

 rat reaches full growth the need for suprarenal tissues decreases because 

 the growth processes are reduced and no great muscular activity demands 

 suprarenal function. On the other hand in the wild rat although growth 

 processes are reduced at maturity, the extremely active muscles require 

 great function of the suprarenals. 



AVatson kept a series of wild rats in captivity for 10 weeks. At the end 

 of that time the average percentage weight of the suprarenals was 0.038. 

 They were fed bread and milk. The decreased activity would seem to 

 account for this unless it were due to a change in diet. 



Just what part the suprarenals might play in muscular activity is un- 

 certain but there is evidence that epinephrin may be of importance in 

 muscular fatigue. The quantity of epinephrin in the suprarenals is very 

 much decreased by great muscular fatigue (Batelli and Boatta, Carl). 

 This has peculiar significance when connected with the observation that 

 epinephrin delays the onset of fatigue in skeletal muscle, which has been 

 demonstrated by Panella, Cannon and Nice, and Gruber. 



Whether this beneficial effect is due to an increase in the circulation 

 in skeletal muscle (Hoskins, Gunning and Berry) or to some other in- 

 fluence, Gruber's work would indicate that the effect is not wholly cir- 

 culatory, for after denervation of the muscle while the vessels are in a 

 dilated state, epinephrin benefits the fatigued muscles without an ac- 

 companying dilatation ; in fact the circulation may decrease. It has been 

 suggested that epinephrin neutralizes or destroys the fatigue products. 

 Carnot and Josserand found that a dose of epinephrin which caused a 

 rise of 10 cm. (Tig) in the blood pressure when injected into the femoral 

 artery of a resting leg produced a rise of only 1.5 cm. when injected into 



