Reaction of the Perfused Isolated Lung of Sensitized Guinea Pig to Horse Serum

Abstract

There has been great need of a simple method of studying objectively the response of the bronchial smooth muscle of the sensitized guinea pig to antigens. Older methods of observing changes in bronchial tone in intact animals are not only difficult of application to small animals but are often complicated by changes in circulation which make the interpretation of such observations uncertain. More recently Koessler and Lewis 1 obtained striking graphs in the sensitized guinea pig by studying the changes in intrapulmonary pressure and the corresponding variations in ventilation depending upon varying degrees of bronchospasm produced by the injection of horse serum into horse serum sensitive guinea pigs. Similar responses may be obtained by perfusing the isolated sensitized lung of the rabbit (Sollmann and von Oettingen 2 ) and of the guinea pig (McDowall and Thornton 3 ). This method is superior to the use of ring preparations of tracheal or bronchial muscle because by means of it a study can be made of the reactivity of the smaller bronchioles which play the major part in bronchial reactions.

This method has been applied by us to a study of the reactivity of the bronchial smooth muscle of guinea pigs sensitized to horse serum. The procedure consists essentially of perfusing the bronchi through the trachea, the fluid making its exit through scarifications on the lung surface. The arrangement of apparatus and the technical details are described by Sollmann and von Oettingen, 2 and Warnant. 4 We have used the perfusion fluid recommended by McDowall and Thornton. It has the following composition, the amount of each salt being expressed in %: NaCl 0.659, KCl 0.046, CaCl₂ 0.005, MgCl₂ 0.009, NaH₂PO₄ 0.01, Na₂ HPO₄ 0.008, NaHCO₃ 0.252. Such a modified Locke's solution is less likely to cause spasm of the bronchi because it contains less calcium and a small percentage of magnesium and its content in buffer salts keeps the hydrogen ion concentration constant for long periods of time.