Anaphylactic Reactions in Isolated Organs 



283 



(d) Lungs: Marked increase in perfusion resistance, re- 

 ducing the perfusion flow fully seventy-five per cent. Marked 

 pulmonary edema : non-collapse of lungs on releasing the tracheal 

 clamp. 



The reactions in the intestines, liver and lungs are qualitative- 

 ly similar to the histamine reactions previously reported. 1 The 

 reactions in the hind quarters, however, differ from the his- 

 tamine reactions: (a) in the absence of the marked edema char- 

 acteristic of the histamine perfusion, and (b) in the substitu- 

 tion of a slight vasoconstriction for the marked histamine vaso- 

 dilation. 



If reactions similar to those observed on blood-free perfusions 

 of isolated organs take place during anaphylactic shock in the 

 intact animal, one can readily understand why the acute fall in 

 arterial blood pressure, the characteristic feature of canine ana- 

 phylaxis, does not take place in dehepatized dogs. Peripheral 

 vasoconstriction (intestines, hind quarters) would tend to in- 

 crease the arterial blood pressure in these animals, while the 

 reduced blood volume from edema would tend to decrease this 

 pressure. The combined action of these two factors might 

 readily leave the blood pressure unaltered. The pulmonary 

 vasoconstriction is presumably compensated for by an increased 

 strength of the myocardial contractions. 



Defibrinated blood perfusions will be reported later. 



i Mauwaring, W. H., Monaco, R. E., and Marino, H. D., Proc. Soc. Exp. 

 Biol, and Med., 1922, xx, No. 5. 



