Fig. 22. Blood pressure tracing from a cast showing the effect of exclusion of the 

 naturally liberated epinephrin on a cardiac arrhythmia present at the beginning of the 

 experiment (under urethane), and demonstrating that the epinephrin discharged from 

 the suprarerials exerts an action upon the heart. The vagi were cut at the beginning 

 of the experiment. At 4 the suprarenal blood was excluded from the circulation by 

 closing the cava pocket. At 5 the pocket was released. At 6 the pocket was again 

 closed. The opening of the pocket augmented the irregularity and so did the injection of 

 "adrenalin" at this stage, in such amounts as were used to assay the epinephrin output. 

 A very large amount of epinephrin, on the other hand (0.5 c.c. of a 1:35,000 solution), 

 caused the irregularity to disappear (injection from 14 to 15 in the figure). The 

 same reversal of the original effect was seen at a later stage in the experiment when the 

 pocket was closed off, the irregularity now developing or becoming greater during the 

 period of closure and disappearing, after the usual latent period, when the pocket was 

 opened. At 37, e.g., a pocket which had been closed 3 minutes was opened. At 38 to 

 39, 1 mgm. of strychnin sulphate was injected, and the irregularity disappeared a little 

 before 40 the irregularity returned and was increased by closing the pocket at 40. 

 After 3 minutes, the pocket was opened at 41 and the irregularity disappeared com- 

 pletely for 2 or 3 minutes. The changes could have nothing to do with any effect of 

 the abstraction of the small quantity of blood collected in the pocket on the filling of 

 the heart. The zero line, coincident with the time trace (seconds and 10-seconds), has 

 been moved up 42 mm. for observations 4 to 6; 40 mm. for observations 14 and 15; and 

 20 mm. for observations 37 to 41. The finer details of the irregularity in the curve 

 have been somewhat obscured in the reproduction. (After Stewart and Rogoff, J. 

 Pharm. & Eacper. Therap.) 



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