The bronchorelaxant effect of helicidine, a Helix pomatia extract, involves prostaglandin E-2 release.

Helicidine is a biological extract prepared from the snail Helix pomatia L. and used in man as an anti-tussive agent. However, its mechanisms of actio n are not fully defined. In this study, we have investigated a possible rel axant effect of helicidine on guinea-pig airway smooth muscle and evaluated the role of prostanoids and airway epithelium in this relaxation, H. pomat ia extract (0.001 - 1 mg/ml) induced a dose-dependent relaxation of guinea- pig trachea pre-contracted with histamine both in the presence and absence of tracheal epithelium. No significant difference in dose-dependency or mag nitude of the relaxation was observed between tracheal segments with or wit hout epithelium (maximal relaxant response of 35 +/- 7 and 25 +/- 7.5%, res pectively). Relaxation of the trachea induced by H. pomatia extract (0.001 - 1 mg/ml) was inhibited by pre-treatment with the cyclooxygenase inhibitor , indomethacin, both in the presence or absence of tracheal epithelium. H. pomatia extract (1 mg/ml) induced a marked and significant increase in pros taglandin E-2 release in tracheal segments with and without epithelium. The se results indicate that helicidine possesses a broncho-relaxant activity w hich is independent of epithelium integrity and which is partly mediated by the release of the relaxant prostanoid, prostaglandin E-2. The origin of p rostaglandin E-2 production in the airways remains to be defined.