The catecholamines in the pulmonary arterial pressor response to acute hypoxia.

A mioderate reduction in the oxygen content of inspired air elicits an increase in the pulmonary arterial pressure in animals and man (1-5). It has been suggested that the catecholamines may be involved in this pressor response (6, 7). However, it is uncertain if this hypothesis applies to the effects of tolerable levels of hypoxia in man, since the experimental evidence for enhanced adrenal activity derives exclusively from observations made during severe hypoxia and asphyxia in animals (8-17). The present study attempted to assess the role of the catecholamines in effecting the pulmonary arterial pressor response to acute hypoxia in man. To supplement these observations on man, experiments were performed on reserpinized dogs to determine whether the pulmonary arterial pressor response to acute hypoxia persists after depleting the pulmonary vascular nerve endings of norepinephrine.