[The relationship between H2 receptor and the pathogenesis of bronchial asthma in guinea-pigs]

H2 receptor (H2R) is one of the three histamine receptor subtypes. In order to explore the relationship between H2R and the pathogenesis of bronchial asthma, we investigated the effects of H2R agonist impromidine on guinea-pig isolated tracheal smooth muscle and the effects of dimaprit on the lung function of guinea-pigs provoked by antigen.

(1) Impromidine (10(6) mol/L) relaxed partly the guinea-pig isolated tracheal spirals contricted by histamine challenge. After pretreating the spirals with impromidine, the maximum response to histamine was reduced in a dose-dependent manner and the cumulative dose-response curve to histamine was shifted to right. (2) Dimaprit (3mg/kg) given by intravenous injection protected the lung function from damage caused by antigen. These results suggest that H2R agonist produces relaxation of guinea-pig tracheal smooth muscle and inhibits the release of inflammatory mediators in anaphylactic reaction. We concluded that H2R plays some protective roles in the pathogenesis of bronchial asthma.