The Paradoxical Pupil Reaction in Cats, Before and After Interfering with the Suprarenal Medulla

Abstract

Cats, with normal suprarenals, with medulli-suprarenals removed and with splanchnic nerves cut, were experimented on. The left upper cervical sympathetic ganglion was removed about a week before, and the ciliary ganglion on the side one or two days before. Asphyxiation by mechanically covering the nose and mouth, muscular exercise with a treadmill, cooling by means of introducing cold water into stomach with a stomach tube, sensory stimulation of the moist pinna with induction shock, chemical irritation of the nasal mucosa with ammonia, and emotional excitement by a barking dog were applied. All the agencies were capable of exciting the paradoxical pupil dilatation, the asphyxia was most potent and the barking dog was the weakest agent. Experimental conditions for confronting the cat and dog were certainly inadequate to excite animals vigorously. Demedullation of the suprarenal capsulae and cutting the splanchnic nerves interfere largely with the magnitude of the paradoxical pupil dilatation through these agencies; a barking dog was now incapable of causing any paradox, while asphyxiation and cooling were always attended by a small paradoxical dilatation. With the other agencies the paradox failed to occur infrequently. Such data apparently depend upon the potency of eliciting the paradox reaction.§