Changes in phrenic, mylohyoid, and hypoglossal nerve activities that follow intravenous infusions of aminophylline

Abstract

We determined whether or not administrations of aminophylline would produce differential changes in activities of the hypoglossal nerve and the mylohyoid branch of the trigeminal nerve, compared with phrenic nerve activity. The former two nerves innervate muscles influencing the upper airway, whereas the phrenic nerve innervates the diaphragm, a major muscle of the ventilatory pump. Neural activities were recorded in decerebrate, vagotomized, paralyzed, and ventilated cats. Peak integrate phrenic activity generally increased with intravenous infusions of cumulative doses of aminophylline ranging from 1.0 to 64 mg/kg. The concomitant changes in trigeminal and hypoglossal activities were extremely variable. In some animals, peak integrated trigeminal and/or hypoglossal activities rose progressively with increasing doses of aminophylline. For other animals, maximum levels of neural activities were attained at intermediate doses and declined at higher dose levels. Results were similar in animals having bilateral sections of the carotid sinus nerves. The variable changes in neural activities may reflect the multiple sites of action of aminophylline in the brain stem.