AIRWAY RESPONSES TO LOW CONCENTRATIONS OF ADRENALINE AND NORADRENALINE IN NORMAL SUBJECTS

Abstract

Airway, cardiovascular and metabolic responses were measured in 6 normal subjects during separate infusions of adrenaline [epinephrine] and noradrenaline [norepinephrine, NE]. Four incremental infusion rates of the catecholamines (4, 10, 25 and 62.5 ng/kg/min) produced circulating levels of EN and NE within the physiological range. Maximal expiratory flow rates at 25% of vital capacity measured from partial flow-volume curves increased sequentially with increasing E concentration. Increases in maximal expiratory flow rates at 25% and 50% of vital capacity measured from complete flow-volume curves were not statistically significant, nor were the changes in specific conductance. Small but insignificant changes were observed in heart rate and blood pressure during NE infusion. Plasma glucose increased and serum K fell during EN infusion. No significant airway, cardiovascular or metabolic responses were seen during NE infusion. Apparently, at concentrations found in physiological circumstances, influences flow rates in small airways. Circulating NE does not appear to be important in the control of airway caliber in normal subjects.