THE SEAT OF ACTION OF SULFIDE ON PULMONARY VENTILATION

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Abstract
Effects of common carotid and vertebral intra-arterial, femoral intravenous, and fourth ventricle injections of sulfide (Na2S) in anesthetized dogs, before and after carotid sinus (and body) denervation and/or vagotomy, were studied. Traces of the chemical give rise to an almost immediate, abrupt, and intense augmentation of respiration, arising reflexly at the carotid sinus region. It has a much less intense slowing action on respiration by virtue of vagal ending stimulation, which is masked by the carotid reflex in the normally innervated animal. The intracranial action is slower, requires considerably greater dosage, and is as a whole usually a diminution in pulmonary ventilation. A depression may be preceded by a slight stimulation and followed by a partially compensatory overshooting. Studied by means of 4th ventricle injections, the intracranial effect exhibits more of an augmented rate.