378 Dr. S. W. Patterson. The Antagonistic 



Fig. 1. — Effect of Adrenalin on Inferior Vena Cava and Left Auricle Pressures. I.V.C 

 pressure reduced from 260 mm. H 2 to 80 mm., and L.A. from 250 to 100 ; rate 

 of heart increased from 22 beats in 10 sees, to 40 in 10 sees. 



Adrenalin can improve a heart that is not doing well, so that it is then 

 able to work better. In Table I, adding adrenalin enabled the heart to keep 

 up its output against a higher arterial resistance than before. But if the 

 heart muscle is doing its work badly, or if the " contractile substance " is 

 used up, so that the heart has lost the material with which it can respond, 

 adding adrenalin may have no good effect, and the venous pressures remain 

 high (see Experiment 5 in Table III). 



