EFFECTS OF VACCINATION WITH HEMOPHILUS-INFLUENZAE ON ADRENOCEPTOR FUNCTION OF TRACHEAL AND PARENCHYMAL STRIPS

Abstract

H. influenzae can be isolated from the deeper airways of asthmatic patients. The effect of vaccination with H. influenzae on .alpha. and .beta. adrenoceptor function was studied in guinea pig tracheal spirals and lung parenchymal strips. The tracheal spirals from H. influenzae-vaccinated animals showed significantly less relaxation to isoproterenol as compared to controls, independent of whether the trachea was maximally contracted with carbachol or only exhibited an intrinsic tone. An increased contractile response to carbachol was observed in these spirals. To isoproterenol in the presence of a .beta.-2 adrenergic antagonist (H35/25), or to salbutamol alone, the tracheal preparations from H. influenzae-vaccinated animals showed a decreased relaxation. Thus both .beta.-1 and .beta.-2 subtype adrenoceptors may be involved. Lung parenchymal strips from vaccinated guinea pigs relaxed significantly more to the drugs. This effect was not influenced by H35/25 but could be inhibited by phenoxybenzamine. Histamine-induced contraction did not differ between the groups. H. influenzae causes a partial blockade of the .beta. adrenoceptors in tracheal spirals and may have important implications in asthmatic bronchitis. Parenchymal lung strips of the H. influenzae-pretreated group showed an increased relaxation.