Ventilatory effects of the stress hormones in normal man

The ventilatory responses to catecholamine infusions have been well studied. Increases in plasma levels of cortisol and glucagon during stress may exert a synergistic effect with epinephrine. We examined the effect of epinephrine and a combined hormone infusion in four normal postabsorptive subjects. On three separate occasions each subject was assigned randomly to receive a 5.5-h infusion of saline (control), epinephrine (1.2 micrograms/m2 . min), or epinephrine plus cortisol (5 mg/m2 . min) plus glucagon (3 mg/kg . min). Oxygen consumption (VO2), CO2 production, minute ventilation (VE), tidal volume (VT), frequency (f), inspiratory flow, and inspiratory time during room-air breathing and inhalation of 2% and 4% CO2 were measured before infusion and during the last 2 h of infusion, using a noninvasive canopy system. VO2 increased significantly (p less than .05) from the control condition during both combined and epinephrine infusions (23% and 11%, respectively). The increase in VE was related linearly to the increase in VO2, and was primarily due to an increase in VT; however, there was a small rise in f. The VE-PaCO2 regression during CO2 inhalation was shifted leftward to an equal degree during both infusions. These data indicate that cortisol and glucagon augment the calorigenic action of epinephrine; ventilatory effects are augmented in relation to the changes in VO2.