PHYSIOLOGY AND BIOCHEMISTRY OF SHOCK 425 



terase; and (b) it modifies the cells of the terminal organs, rendering 

 them refractory to acetylcholine (parasympathofrenatric action). 

 These two effects are intensified by increasing the dose of atropine. 

 A small dose which inhibits choline esterase (anti-acetylcholinolytic) 

 favors the action of acetylcholine. A higher dose of atropine, though 

 anti-acetylcholinolytic, renders the cells of the terminal organs refrac- 

 tory to acetylcholine. It thus makes it necessary that a greater dose of 

 atropine be used to protect the animal from the action of acetylcholine, 

 and anaphylactic shock. In the rabbit, it is necessary to use enormous 

 amounts of atropine to prevent shock, because the tissue of rabbits con- 

 tains an enzyme which inactivates atropine by splitting it into tropine 

 and tropic acid. 



In the guinea pig, toxin-antitoxin mixture is known to fail to 

 produce shock. After the eserinization of the animal, the same mixture 

 provokes a classical acetylcholine type of anaphylactic shock. Two 

 successive injections of eserine (0.025 mg. and 0.1 mg. /injection) 

 were subcutaneously administered to a guinea pig. After a period of 

 eight minutes, the intravenous injection of toxin-antitoxin complex 

 produced a non-fatal anaphylactic shock. When 0.5 mg. of eserine/ 

 injection was administered twice, after a period of eight minutes the 

 intravenous injection of 1 ml. of toxin-antitoxin mixture into the 

 jugular vein caused immediate shock and death in five minutes. In 

 this series of tests eighteen guinea pigs were used. 



In another set of experiments, the intestine of the rabbit, which 

 is very sensitive to acetylcholine, immersed into Tyrode's solution 

 containing a mixture of diphtheria toxin-antitoxin mixture, showed 

 marked tonus. After the shock, the bath was replaced with a fresh 

 Tyrode solution and a new mixture of toxin and antitoxin was added; 

 a lesser degree of contraction of the intestine was observed. A third 

 test with fresh materials similarly made eliminated the response of 

 the same intestine, indicating the exhaustion of acetylcholine in the 

 intestine. However, when acetylcholine was added to a fresh bath 

 containing toxin-antitoxin complex, the deacetylcholinized intestine 

 responded as in the first test. Histamine also plays a role in the pro- 

 duction of anaphylactic shock, but it is claimed that there is no 

 histamine production without the production of acetylcholine. 



Epinephrine has been shown to have an important influence upon 

 the nervous system vdthin the spinal cord, and on synaptic trans- 



