The oculorespiratory cardiac reflex in the dog.

Intraorbital and intracranial electrical stimulation as compared with manual eye pressure indicates that in the dog the afferent pathway for the oculorespiratory cardiac reflex is carried by the ophthalmic division of the fifth cranial nerve. The effects on cardiac and respiratory arrythmia produced by using intravenous atropine have demonstrated that, although reflex bradycardia can be abolished, respiratory arrest is more profound and lasts for a significantly longer period of time. E llectrical stimulation studies in the cat have defined the afferent pathway of the oculorespiratory reflex. 0 - s Although no cardiac changes were observed in the cat, Aserinsky and others 1 - *•'' 3> 3 have indicated that in the dog bilateral manual pressure on the eyes produced both respiratory and cardiac changes. The present study was designed to determine the afferent pathway of this combined reflex in the dog, to compare the effect of ocular pressure to that of electrical stimulation, and to investigate the role of atropine in modifying this reflex. Methods and materials