Respiratory responses to stimulation of afferent vagal fibres in rabbits

In the experiments with 43 paralyzed rabbits ventilated artificially under general anaesthesia with halothane the effect of electrical stimulation of the central end of the vagus nerve on respiratory pattern was investigated. The analysis of respiratory responses to varying parameters of stimulation, and comparison of results with the experiments in which stimulation of pulmonary receptors was used, confirmed the view that the activities transmitted along the thick myelinated fibres of the vagus nerve exerted an inhibitory effect on the generation of inspiratory activity, while the activities transmitted along thin myelinated fibres accelerated the respiratory rate. The integrative processes transforming the activity of thick fibres had a time constant shorter by two orders than the integration of responses to stimulation of thin fibres.