Parabens, the C1-C4 alkyl esters of p-hydroxybenzoic acid, have been used since the 1930s as bacteriostatic and fungistatic agents in drugs, cosmetics, and foods. Recently, several reports of paraben-induced asthma have been published. The present investigation was conducted to explore the effect of parabens on the actions of various bronchoconstrictors.
Male guinea pigs, weighing 250-300g, were sacrificed. Guinea pig trachea was removed, cut spirally 1.5mm in width and 2.5cm in length, suspended in bioassay glass chamber and superfused with Krebs-Henseleit solution at 37°C saturated with oxygen and carbon dioxide (95:5, v/v). Contractile responses of guinea pig tracheal tissues were detected by an isotonic transducer and displayed on a polyrecorder.
1) The dose-response curve of acetylcholine was shifted upward by combining methylparaben and this shift became more dominant by increasing the dose of methylparaben.
2) Acetylcholine, histamine and serotonin-induced contractile responses of tracheal tissues were potentiated dose-dependently by combination with methylparaben.
3) Acetylcholine, serotonin, histamine and prostaglandin F2α-induced contractile responses of tracheal tissues were potentiated dose-dependently by combining propylparaben and reached a maximum at a dose of 2.5μg/ml.
4) Acetylcholine, serotonin, histamine and prostaglandin F2α-induced contractile responses of tracheal tissues were potentiated dose-dependently by combination with ethylparaben and reached a maximum at a dose of 2.5μg/ml.
5) The above results may suggest that such potentiating effects of parabens on the action of bronchoconstrictors could be the pathogenesis of paraben-induced asthma.
