Abstract
Bronchial asthma is a clinical syndrome manifested by reversible and intermittent obstruction of bronchi. The reported incidence of aspirin and indomethacin-induced asthma is the highest among all drug-induced asthmas. Nevertheless the etiology of indomethacin-induced asthma is still unknown.
The present investigation was conducted to explore the effect of indomethacin on the relaxing responses of guinea pig tracheal tissues with various bronchodilators.
Male guinea pigs, weighing 250-300g, were sacrificed. Guinea pig tracheas were removed, cut spirally in strips 1.0-1.5mm in width and 3.0-4.0cm in length, suspended in bioassay glass jackets, superfused with Krebs-Henseleit solution at 37°C, and saturated with oxygen and carbon dioxide (95:5, v/v). Relaxation of tissues was detected by an isotonic transducer and displayed on a polyrecorder.
1) The relaxing responses of guinea pig tracheal tissues with various doses of isoproterenol and prostaglandin E2 were potentiated slightly with continuous infusion of indomethacin at a dose of 5×10-8M, afterwards they showed the significant decrease by increasing the dose of indomethacin.
2) The relaxing responses of guinea pig tracheal tissues with 5ng/ml of salbutamol hemisulfate and 500ng/ml of aminophylline were attenuated dose-dependently with continuous infusion of indomethacin.
3) The above results suggest that inhibition of endogenous prostaglandin E2 synthesis by indomethacin may cause indomethacin-induced asthma.
