RELATION SUPRARENAL GLANDS TO CIRCULATION 205 



nic and peripheral responses being obtained after occluding first one group 

 of arteries and then releasing these and occluding the second group. 

 In each instance clamping the extra-splanchnic arteries caused the vascular 

 response to the standard dose of epinephrin to change from the normal 

 fall to a rise of pressure (Fig. 4). Clamping the splanchnic vessels, 

 on the other hand, in all except one case, permitted the eliciting of de- 

 pressor effects only. 



Effects on the Circulation of the Limb. The first studies of the 

 effects of epinephrin on the limb volumes were reported in Oliver and 

 Schafer's paper previously discussed. Contraction usually was observed, 

 though occasionally expansion of the limb occurred. These results were 



Fig. 4. Differential effects of epinephrin, 0.2 c.c. 1 : 100,000 solution by vein, upon 

 blood pressure, when the whole circulation, the splanchnic area, and the limbs re- 

 spectively were chiefly involved. In a, normal conditions maintained; &, the periph- 

 eral vessels were clamped; c, splanchnic arteries clamped. Time, 5 seconds. (After 

 Hartman, Am. J. Physiol.) 



confirmed by Vincent, who added the observation that expansion was par- 

 ticularly likely to occur toward the end of the experiment. This ex- 

 pansion was regarded as "passive." In certain instances one limb ex- 

 panded while its fellow .contracted. This inconsistency was ascribed to 

 a struggle between active constriction of the arterioles and dilatation of 

 the larger vessels within the plethysmograph. 



A considerable number of studies have been made regarding the effects 

 of epinephrin on the outflow from perfused limbs. In the use of the 

 Lawen-Trendelenburg perfusion method of assaying epinephrin abundant 

 proof has been secured that this substance in all dilutions ordinarily 

 causes vasoconstriction in the legs of the frog. Gerhardt attempted to 

 study directly under the microscope the effects of epinephrin on the blood- 

 vessels of living muscle. He was unable to detect changes in the caliber 

 of either the arterioles or the venules, but inferred that the arterioles must 

 have constricted since otherwise the veins would have shown dilatation 

 as the result of increased arterial pressure that ensued. 



