RELATION SUPRARENAL GLANDS TO CIRCULATION 189 



more commonly observed but expansion was also frequently seen. The 

 difference was ascribed by the authors to variations in the relative parts 

 played by passive expansion in the larger vessels and active constriction 

 in the smaller. In the kidneys, in some instances, towards the end of 

 the experiments "passive dilatation" was observed. No direct plethysmo- 

 graphic studies were made of the reaction in the intestine, but by direct 

 inspection well-marked generalized splanchnic vasoconstriction was 

 evident. 



Attention was directed to the problem as to how the vasoconstrictor 

 effect was mediated. The role of the nervous system was first investigated. 

 It was found that perfusion of suprarenal extracts through the vascular 

 bed of the frog was equally effective after section of the spinal cord or of 

 the nerves to the limbs. Hence it was concluded, and correctly, that the 

 effect is largely, at any rate, peripheral and independent of the nervous 

 system proper. That the effect of the extracts was upon the tissues 

 directly was indicated to some extent also by the brief latent period in- 

 tervening before the reaction was apparent. 



In the experience of these investigators, the extracts invariably pro- 

 duced a rise of arterial pressure, "never a fall." The important ob- 

 servation was also made at this time that the pressor effect of a given 

 dose of suprarenal extract was materially augmented if the vagi were 

 cut or paralyzed by a suitable dose of atropin. Under these conditions 

 Oliver and Schafer witnessed rise of blood-pressure from two to five 

 times the original height. The persistence of the effect varied more or 

 less in accordance with the dosage. The maximum persistence seen in 

 the dog was four minutes, and in the rabbit six minutes, following 

 single doses. The blood-pressure curves reproduced by way of illustra- 

 tion of the report are mostly of the smooth, monophasic wave form, 

 though occasionally curves with a preliminary dip, such as have since be- 

 come very familiar to pharmacologists, were seen. Curiously enough, the 

 depressor phase which is so characteristic of epinephrin curves was never 

 secured. 



The effects of suprarenal extracts upon the heart were studied both in 

 frogs and in mammals. When the isolated frog heart was perfused the 

 addition of suprarenal extracts led to a marked increase in the rate and, 

 less definitely, an increase in the strength of the beat. The irregulari- 

 ties of force and rhythm not uncommonly seen in such isolated heart 

 preparations, were not infrequently elicited. In case of the mammal 

 with the vagi intact, the effect, on the other hand, was commonly a marked 

 inhibition. This was first apparent in the auricles. It was usually pre- 

 ceded by a brief augmentation which rarely lasted, however, more than 

 one or two minutes, Following the inhibition of the auricles, the ven- 

 tricles then assumed a slower rate. This inhibitory effect was totally 

 abolished by vagotomy or atropin. Instead of depression, a marked 



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