986 ANAPHYLAXIS AND ANAPHYLACTOID REACTIONS 



the heart, trembling, expulsion of urine, cyanosis, pupillary relaxation, convulsions, 

 and death with the larger doses." 



The morbid anatomy has been studied principally in guinea pigs, although certain 

 of the significant changes are to be seen in other animals. With most of the agents the 

 mode of death is cardiac rather than asphyxial. Consequently, marked dilatation of 

 the heart, particularly of the right side, associated with hyperemia and hemorrhage 

 in various viscera is likely to be striking. Pulmonary distention is not frequent, but 

 local areas of emphysema may be encountered. Usually the lungs show marked 

 hyperemia with gross or only microscopic hemorrhages. The notable exception is 

 peptone, which, as stated above, produces lung changes almost identical with those 

 of anaphylaxis. The same may be true of histamine, agar, and a few other agents. 



The microscopic examination of the lungs, following many of the agents, com- 

 monly shows some form of thrombosis or embolism in the pulmonary vessels, especial- 

 ly the small arteries and capillaries. The constitution of these varies with different 

 agents but is fairly constant with each. The vessels may be plugged with masses of 

 corpuscles, red or white predominating, more or less conglutinated, and with small 

 amounts of fibrin. With some agents the cells are entirely large mononuclear with 

 little or no fibrin. With others, notably Fuller's earth, the mass may be almost en- 

 tirely fibrin. Following intraperitoneal injection of histamine, masses of platelets 

 blocking the capillaries are conspicuous. Bronchoconstriction is variable. Perivascu- 

 lar and peribronchial edema are common, and intra-alveolar edema not infrequent. 



The physiological alterations are variable. Most of the agents produce an eleva- 

 tion of body temperature, and relatively few any material fall. Increased capillary 

 permeabihty and edema are common, but such agents as calcium phosphate, barium 

 sulphate, iron phosphate, silicic acid, and gelatin may prevent the edema of mustard- 

 oil irritation. 



Fall of systemic blood pressure is a common result, principally due to blockage 

 of pulmonary circulation. Abe' has demonstrated increase in pulmonary arterial pres- 

 sure following use of histamine, peptone, and tissue extracts, and Jackson and Smith^ 

 following arsphenamine. Abel and Ceiling^ have demonstrated peripheral vasodilata- 

 tion following peptone and histamine administration. 



Most of the agents do not excite smooth muscle contractions. "Exceptions are 

 histamine, peptone, serums, tissue extract, congo red and quinine, which tend to 

 increase excitability." Perfusion of guinea pig lungs with agar, toxified agar, peptone, 

 and histamine leads to reduction in caliber of the bronchi, but this is not relieved by 

 atropin and is probably due to vascular changes and edema rather than to muscle 

 contraction. Perfusion with peptone and histamine may lead to block in the liver, but 

 that this is due to smooth muscle contraction is not established. It will be seen that 

 there are few agents which produce smooth muscle contraction and that broncho- 

 constriction, muscular in origin, is not proved. Certainly there is no such regularity 

 of action on smooth muscle by the anaphylactoid agents as is true in anaphylaxis. 



' Abe, K.: Tohokn J. Exper. Med., i, 398. 1920. 



* Jackson, D. E., and Smith, M. I.: /. Pharmacol. &° Exper. Therap., 12, 221. 1918. 



3 Abel, J. J., and GeilinR, E. M. K.: ibid., 23, i. 1924. 



