W. H. MANWARING 995 



VASOMOTOR REACTIONS 



On account of the explosive edemas of certain tissues in acute anaphylaxis, 

 anaphylactic vasomotor reactions are difficult to study by ordinary plethysomo- 

 graphic methods. Perfusion methods are usually applied to such determinations. 

 Coca/ for example, demonstrated a marked increase in the perfusion resistance of the 

 pulmonary artery in rabbits dying of anaphylactic shock. Immediately after death, 

 the tip of the heart was cut off, and a cannula tied into the pulmonary artery. The 

 cannula was connected with a pressure bulb filled with warm saline solution. In nor- 

 mal rabbits a pressure of lo-cm. H2O is usually sufficient to cause a rapid flow of the 

 perfusion fluid from the left ventricle. After acute anaphylactic shock, a pressure of 

 at least 90-cm. H2O is usually necessary to produce a similar flow. Coca believes this 

 increased perfusion resistance is due to vasoconstriction in the pulmonary arterioles. 



The relatively blood-free lungs may be tested for their independent anaphylactic 

 potentiality by perfusion methods. Well aerated Locke's solution or one of its modern 

 variants is used as the perfusion fluid. In dogs the most convenient method is to tie 

 the afferent cannula into the superior vena cava, and the efferent cannula into the tip 

 of the left auricle, all collaterals being ligated.^ The lungs are then inflated to their 

 mid-respiratory volume, and the trachea clamped. Perfusion pressure, about 25-mm. 

 Hg. In a t^-pical anaphylactic reaction in blood-free canine lungs, the rate of per- 

 fusion flow is usually reduced to about one-quarter the initial flow, within three 

 minutes after adding specific foreign protein to the perfusion fluid. By the end of five 

 minutes, the lungs are remarkably ederaatous. On releasing the trachial clamp the 

 lungs do not collapse. A large amount of clear frothy fluid escapes from the trachea. 



A similar perfusion method applied to the isolated rabbit lungs will show a very 

 marked increase in perfusion resistance on the addition of histamine to the perfusion 

 fluid, ^ but we have thus far been unable to demonstrate an appreciable change in the 

 perfusion resistance of hypersensitive lungs on the addition of specific foreign protein 

 to the perfusion fluid. "^ We are, therefore, inclined to attribute the marked increase 

 in perfusion resistance described by Coca to factors other than vasoconstriction. 



One of the most promising perfusion methods thus far applied to anaphylaxis is 

 perfusion of the entire lower half of h>^persensitive frogs. The hind quarters are freed 

 from blood plasma and tissue lymph by a twenty-four hour preliminary perfusion 

 with Ringer's solution. Arnoldi and Leschke^ report a slight vasoconstriction in 

 normal frogs on adding human serum to the perfusion fluid, with a marked vasodila- 

 tation in hypersensitive frogs. 



VENOUS BLOOD PRESSURE 



A few studies of anaphylactic changes in the blood pressure in the systemic veins 

 have been made, usually by means of a cannula in the jugular vein.^ In dogs, for 



' Coca, A. F.: /. Immunol., 4, 219. 1919. 



^Manwaring, W. H., Chilcote, R. D., and Hosepian, V. M.: ibid., 8, 233. 1923. 



^Manwaring, W. H., and Marino, H. D.: ibid., p. 317. 1923. 



4 Manwaring, W. H.: unpublished work. 



5 Arnoldi, W., and Leschke, E.: Deutsche med. Wchnschr., 46, 1018. 1920. 

 ^ Auer, J.: loc. cit. 



