EMEEGENCY FUNCTION OF SUPEAEENAL MEDULLA 177 



Discussion of the Positive Evidence 



Objection to this evidence of increased suprarenal secretion has "been 

 raised by Stewart and Eogoff, who declare that no reliable conclusion 

 can be drawn from it without knowledge of the rate of blood flow. 



The Catheter Method. In criticism of the catheter method used by 

 Cannon and Hoskins, they state that the results obtained by it are valid 

 only if the blood flow is assumed to be constant during the whole experi- 

 mental period ; and second, that the method does not permit any judgment 

 on this point (Stewart and Eogoff (t), 1917). Thus, if there be a con- 

 tinuous secretion of epinephrin undisturbed by reflex stimulation, as 

 they maintain is the case, there could be an increased concentration only 

 if the blood flow through the suprarenal vessels were retarded. There 

 is another possibility, however, which should be considered. The blood 

 flow through the suprarenal vessels might be increased. Strong sciatic 

 stimulation has a well-known pressor effect. This may be due largely 

 to reflex splanchnic stimulation. But there is no evidence that splanchnic 

 stimulation causes constriction of suprarenal vessels. Indeed, the care- 

 ful observations of Burton-Opltz and Edwards have shown that stimula- 

 tion of the splanchnic nerves causes a greater blood flow through the supra- 

 renal vein, a result which Biedl(fr) had previously noted (1897). With 

 a heightened general blood pressure and at least no constriction of the 

 suprarenal vessels, the blood flow through these vessels must necessarily 

 be increased. Under these circumstances, on the basis of Stewart and 

 EogofFs argument, the epinephrin would be more dilute rather than more 

 concentrated in the suprarenal blood. 



In answer to this consideration they have suggested that the blood 

 from the suprarenals is only a small portion (perhaps 1/100 to 1/200) 

 of the blood passing along the inferior cava, and has, therefore, no sen- 

 sible influence on the rate of flow in the cava. Because of vasoconstric- 

 tion they assume this flow to be retarded to a. degree which causes a suf- 

 ficient concentration of epinephrin to evoke typical effects. They have 

 offered no evidence that their assumption is true. - On the other hand, 

 with increased arterial pressure, a faster heart rate, and a deepened 

 respiration such as occur in pain and excitement a faster flow in the 

 inferior cava would naturally result. Direct study of the blood flow in 

 the inferior cava under experimental conditions has recently been made 

 by Opitz. He has found that both splanchnic stimulation and reflex 

 stimulation from the sciatic nerve (the mode Cannon and his collaborators 

 employed) resulted in a faster flow through this great venous trunk. The 

 faster flow in the cava just anterior to the suprarenal veins, that accom- 

 panies reflex stimulation, would, of course, be highly unfavorable for 

 demonstrating an increased concentration of epinephrin, if it were true 



