412 IMMUNO-CATALYSIS 



and myocardial depression following violent excitement and terminal 

 prostration. 



Epinephrine is another substance which has long been known to 

 produce effects which are opposite that of histamine. Injection of 

 histamine will stimulate the release of epinephrine from the medulla 

 of the adrenal gland (Feldberg, 1941). On the other hand, the intra- 

 venous injection of epinephrine in man will produce an increase of the 

 histamine content of the blood plasma (Staub, 1946). Epinephrine 

 and its congeners, however, are not considered as antihistamine drugs 

 (Rose, 1947) since they induce prominent effects such as bronchodila- 

 tion, vasoconstriction, decreased capillary permeability, inhibition of 

 intestinal activity which present the antitheses of those produced by 

 histamine. Atropine and other antispasmodic drugs, and certain amino 

 acids and derivatives of histamine are capable of antagonizing some of 

 the effects of histamine. However, Rose considers that these com- 

 pounds are non-specific since their ability to counteract, or relax smooth 

 muscle and to antagonize acetylcholine, barium and spasmogenic 

 agents equals or exceeds their effectiveness in opposing histamine. 

 Those drugs which are potent-histamine antagonists are said to act as 

 blocking agents with some degree of specificity as regards antihistamine 

 action. Pharmacologically, the specificity is considered relative and not 

 absolute. 



e. Histamine and Antihistaminic Substances 



H 



I 

 C 



^\ 



N N— H 



I I 



H— C = C CH2CH2NH2 



Histamine 



H 



CH3— C— < >— CH; 



C2H 



2^5 



CH3 \ O-CH2CH2N =929 F 



\ 



C2H6 



2-Isopropyl-5-methylpIienoxyethyldiethylamine 



