Bronchodilating effects of bambuterol on bronchoconstriction in guinea pigs

AIM: To study the effects of bambuterol (Bam) on bronchoconstriction in gui nea pigs. METHODS: Bronchospasm induced by histamine aerosol, lung resistan ce (R-L) and dynamic lung compliance (C-dyn) changes induced by ovalbumin a erosol in vivo, isolated resting lung parenchyma strips, and carbamylcholin e-induced tracheal constriction in vitro in guinea pig were investigated. R ESULTS: Bam dose-dependently prolonged the time to histamine-induced collap se, ED50 values (95 % confidence limits) of Bam intragastric gavage tig) af ter 1 h, 4 h, and 24 h were 0.74 (0.60 - 0.91), 0.75 (0.61 - 0.91) and 1.00 (0.77 - 1.30) mg kg(-1), respectively. Bam 2 or 10 mg . kg(-1) ig 2 h befo re ovalbumin aerosol partly or almost completely inhibited bronchial challe nge of ovalbumin-induced change of R-L and C-dyn. Bam 0.1 - 1.0 mu mol . L- 1 gave a weak relaxation on isolated tracheal strips induced by carbamylcho line and failed to relax the isolated resting lung parenchyma strips in gui nea pig. CONCLUSION: Bam showed a long-acting bronchodilation by its slow m etabolism in vivo.