Appreciable Way Research Articles

THE EFFECT OF VAGUS SECTION UPON ANAPHYLAXIS IN GUINEA PIGS

Depriving the bronchial muscles of one side of the lungs of their motor innervation does not interfere with sensitization nor the production of the typical anaphylactic lung. There is, therefore, direct sensitization of the muscle substance. Complete degeneration of the vagus nerve, after sensitization has occurred, interferes in no appreciable way with the course of immediate anaphylaxis. Partial degeneration of the vagus nerve, so that the bronchodilator fibers are still physiologically active, after sensitization has taken place, exerts no effect on the symptoms and lung picture of immediate anaphylaxis (very acute anaphylaxis with death after some minutes). No definite evidence was obtained regarding the function of the motor nerve endings in the bronchial muscles in anaphylaxis. The two sides of the lungs in immediate anaphylaxis may occasionally be unequal; when this occurs, the left side, especially the lower lobe, is usually fuller than the right side.

THE PHYSIOLOGY OF THE IMMEDIATE REACTION OF ANAPHYLAXIS IN THE GUINEA-PIG

1. By an immediate anaphylactic reaction we mean the chain of symptoms which occur in highly sensitized guinea-pigs shortly after an intravenous or intracardiac injection of the toxic dose and usually end in death. 2. Immediate anaphylactic death occurs three to five minutes after the toxic injection in highly sensitized guinea-pigs. 3. Immediate anaphylactic death in guinea-pigs is caused by asphyxia; cessation of respiration is secondary to this asphyxia. 4. This asphyxia is apparently produced by a tetanic contraction of the smooth muscles of the bronchioles, which occludes their lumen gradually, so that finally no air enters or leaves the lung, in spite of violent respiratory efforts; the animal is strangulated. 5. The stage of complete broncho-constriction is preceded by a short broncho-dilatation, if the bronchioles have been in a state of tonus previous to the injection of the toxic dose. 6. Anatomically, the lungs of these guinea-pigs are typical and may be used as an indicator of the immediate anaphylactic state when the animal has been immobilized by curarin or by pithing. 7. The lungs of a guinea-pig killed by immediate anaphylaxis are distended and in an inspiratory position so that the diaphragm is pushed down; no marked collapse occurs when the chest is opened and when the lungs are excised in toto; their color is a pale bluish-pink ; the surfaces and borders are smooth; no foam is in the trachea or large bronchi; pieces of lung cut off do not collapse, float lightly on water, and contain a good amount of air and little fluid which escapes on pressure. The blood in the lungs and heart is black when the autopsy is made at once after the cessation of respiration. 8. Section of the vagi in the neck, or curarin (artificial respiration) exerts no appreciable effect on the development of immediate anaphylaxis. 9. This immobilization of the lungs, which is due to a broncho-constriction, is of peripheral origin, for destruction of the spinal cord and medulla affects in no appreciable way the promptness and extent of the typical lung response to the injection of the toxic dose. Artificial respiration is, of course, necessary. At the present time we do not care to state whether the toxic dose exerts its effects upon the bronchial muscles alone or upon the vagus motor endings or upon both structures. 10. The blood pressure in immediate anaphylaxis first shows a rise, which may be considerable; a short maintenance of this high level and then a gradual drop to IO to 20 millimeters of mercury and even less, within ten minutes after injection of the toxic dose. 11. Shortly after injection of the toxic dose a heart block develops, so that auricles and ventricles may beat in a 3:I rhythm; the block is probably due to asphyxia. 12. The cardiac vagus gradually loses its irritability after injection of the toxic dose. 13. Cooling of the guinea-pig delays the reaction to the toxic injection.