RELATION SUPRARENAL GLANDS TO CIRCULATION 213 



states that epinephrin administered intravenously causes contraction of 

 the spleen. 



Hoskins and Gunning(a) (1917) studied the matter further. Dogs 

 were used as the experimental animals. Ether or morphin-ether anesthesia 

 was generally employed but a few animals were decerebrated. In some 

 instances the vagi were cut but this procedure made no apparent difference 

 in the outcome. Epinephrin was introduced into a femoral vein some- 

 times instantaneously and sometimes slowly. Various quantities were ad- 

 ministered, giving pressor effects in some instances and depressor effects 

 in others. Simultaneous records were made of changes in splenic volume 

 or venous outflow, or both, and of changes of femoral arterial pressure. 

 Observations were made upon 17 animals. In the plethysmograph studies 

 65 injections and 18 infusion experiments were made, while the venous 

 outflow series included 34 injections and 20 infusion experiments. In 

 nearly all cases a brief dilatation, supposedly passive, was followed by 

 marked contraction. These results were independent of changes in sys- 

 temic blood-pressure, being obtained both with depressor and with pressor 

 dosages. It was found possible to hold a spleen in a state of uniform con- 

 traction by epinephrin infusion for a period of ten minutes. The effect 

 in the spleen lasted from a half to five and a half minutes after blood- 

 pressure had returned to normal. In no case, with either large or small 

 dosage, was a secondary dilatation observed during an infusion period. 

 Occasionally, however, dilatation occurred after the administration of the 

 drug was discontinued. This effect was not passive, since it was noted 

 when the arterial pressure was either normal or depressed. With no dosage 

 was a pure splenic dilatation obseryed. The threshold for the reaction 

 was highly variable but generally lower than that for changes of arterial 

 pressure. The most sensitive preparation showed contraction with a dos- 

 age of 0.5 c.c. of a 1 :2,000,000 solution, hence the spleen is one of the 

 most sensitive organs in the body. 



The effects on venous outflow were what might be expected from a 

 consideration of the volume changes. During the preliminary dilatation 

 the flow was augmented. The augmentation persisted during the first 

 part of the contraction period while the blood already in the organ was 

 being expelled. During the remainder of the contraction period the flow 

 was depressed, reaching the normal rate at about the same time splenic 

 volume was restored to normal. The depressed outflow during the latter 

 part of the period was obviously due to retention of blood in the expanding 

 organ (Fig. 8). 



Hartman and McPhedran also reported studies on the effect of epi- 

 nephrin in the spleen made about the same time as those of Hoskins and 

 Gunning. Of 10 dogs investigated, 7 showed only constriction in the 

 spleen in response to the whole range of doses of epinephrin adminis- 

 tered. The constriction was more marked and more prolonged with in- 



