Liberation of Epinephrin. 



187 



1. For the eye reactions all that is necessary is to clamp off 

 temporarily a pocket of the inferior vena cava so that only adrenal 

 vein blood enters it. A clamp is applied just above the iliac veins. 

 The renal veins are then clamped and the segment of cava emptied 

 of blood by gently stripping it upwards. Finally a clamp is put on 

 the cava above the adrenal veins. Only a few seconds are oc- 

 cupied in the adjustment of these clamps. Small branches of 

 the segment of cava have been previously tied. The pocket is 

 allowed to fill with blood from the adrenals. When the clamps 

 are removed, the eye reactions are elicited at practically the same 

 time interval as when the splanchnics are stimulated with the 

 vessels free. 



2. After section of both splanchnics (above the diaphragm) 

 the reactions can no longer be obtained. Section of the splanch- 

 nics has therefore greatly diminished, if not abolished, the libera- 

 tion of epinephrin. This is not due to the low blood pressure 

 caused by division of the nerves. For if only the right splanchnic 

 is cut there is little, if any, fall of blood pressure. Nevertheless 

 when the cava pocket is closed off as described, and in addition a 

 clamp is put on the left adrenal vein, the right being free, no eye 

 reaction is elicited on allowing the pocket to empty itself. When 

 the experiment is repeated with the left adrenal vein free the 

 reaction is obtained, although of course less strongly than with 

 both splanchnics intact and both adrenal veins open, since only 

 half the amount of epinephrin is discharged. 



3. To demonstrate the effect of epinephrin liberated into a 

 cava pocket upon the blood pressure of the same animal, a some- 

 what different procedure must be adopted, in order to avoid undue 

 disturbance of the blood pressure curve on forming and on re- 

 leasing the pocket. The lower end of the cava segment is tied 

 permanently after previous ligation of the abdominal aorta and 

 squeezing of blood from the legs. The renal arteries and veins 

 are also tied. When the eye reactions are available to compare 

 with the blood-pressure curve and manipulation of the intestines 

 is avoided during the application of the upper clamp to the cava 

 segment, it is not always necessary that the circulation through 

 the intestines and liver should be interfered with. Even when 

 the blood pressure curve is somewhat irregular the rise of pres- 



