Studies on central respiratory activity in artificially ventilated rabbits.

The level of integrated phrenic nerve activity (C3 root) has been studied under various forms of impairment of respiratory muscle function, such as paralysis (gallamine), pneumothorax and phrenectomy. Experiments were performed in two groups of rabbits artificially ventilated by means of the conventional respirator and the phrenic nerve driven respirator. It was found that both paralysis and bilateral pneumothorax were very strong stimuli exciting central inspiratory activity despite the constancy of ventilation. Under the same conditions phrenectomy caused only slight persistent excitation of the activity studied. It is worth noting that activity in the C3 root contralateral to the cut phrenic nerve trunk was as a rule more strongly stimulated. As artificial ventilation preceded by administration of gallamime is commonly applied in physiological experiments, the possibility of its effect on central respiratory activity will be discussed.