Protective effect of circulating epinephrine within the physiologic range on the airway response to inhaled histamine in nonasthmatic subjects.

The specific airway conductance response of six normal subjects to increasing doses of inhaled histamine was studied on two occasions. On each occasion either epinephrine (0.025 micrograms/kg/min) or saline was infused intravenously during the histamine challenge. This dose of epinephrine, when it was administered to seated normal subjects, produces plasma levels similar to those found at the end of strenuous exercise. Epinephrine caused a significant elevation in the concentration of histamine required to cause a 35% fall in specific airway conductance (PC35), although this was in part caused by a small airway dilator effect. The mean (+/-SD) PC35 rose from 21 mg/ml (+/-6) during saline infusion to 58 mg/ml (+/-27) during epinephrine infusion, p less than 0.05. Levels of circulating epinephrine, similar to those found during exercise in normal subjects, appear to be capable of protecting against bronchoconstrictor stimuli.

RCT Entities:   Population Interventions Outcomes