The overall objective of this project is to obtain a better understanding of the basic mechanisms subserving the control of ventilation and regulation of airway smooth muscle tone. The proposed experiments constitute an effort to control each of three sensory receptor systems independently (pulmonary stretch receptors and - and chemoreceptors) so that their interactions in modulationg phrenic nerve activity and tracheal smooth muscle tone may be investigated. We will determine the relationships of phrenic nerve activity and tracheal caliber to lung stretch at various constant levels of and chemical drive in anesthetized dogs. The role of the carotid bodies and the influence of various anesthetic agents on these relationships will be investigated. Finally, we will determine the effects of reduced serotonin metabolism via tryptophan hydroxylase inhibition on lung stretch reflexes and - and chemoreflexes.
