Effect of eosinophil peroxidase on beta-adrenergic receptor density on guinea pig lung membrane

Abstract

We studied whether eosinophil peroxidase (EPO), an eosinophil granule basic protein, can alter beta-adrenergic receptor (BAR) density on the guinea pig lung membrane. Lung membrane was first preincubated with 1–10 U/ml EPO and then incubated with 10 −4 M NaI and 10 −4 or 10 −6 M H 2O 2 for 2 hours. BAR density was determined using (-) 125 I-cyanopindolol. EPO combined with 10 −4 M H 2O 2 and I decreased the BAR density in a concentration-dependent manner. When only 10 −4 M H 2O 2 was used, the decrease in BAR density was small but significant. When compared to I, bromide was less effective and chloride alone was not effective. These results suggest that EPO is one of the factors responsible for beta-adrenergic blockade in asthma.