AIRWAY ENDOTHELIN LEVELS IN ASTHMA - INFLUENCE OF ENDOBRONCHIAL ALLERGEN CHALLENGE AND MAINTENANCE CORTICOSTEROID-THERAPY

Endothelins (ETs) are 21 amino acid peptides which, in addition to the ir other properties, are potent bronchoconstrictors. Whilst there is e vidence of the involvement of ET in the pathophysiology of chronic ast hma, its contribution to the acute allergic response is undefined. To examine this, we have undertaken segmental bronchoprovocation with all ergen and saline at separate sites in six atopic asthmatics receiving treatment with bronchodilators only and sig atopic asthmatics addition ally receiving treatment with inhaled corticosteroids. Each challenged segment was lavaged 10 min after bronchoprovocation and concentration s of immunoreactive ET were measured in bronchoalveolar lavage fluid. In the non-steroid-treated subjects, there were significantly lower ET levels at the allergen-challenged sites compared to the saline-challe nged sites (p<0.05). In the steroid-treated subjects, on the other han d, there was no significant difference between the two sites, Levels o f ET at the saline-challenged sites were significantly lower in the st eroid-treated subjects compared to the non-steroid-treated subjects (p <0.04). These findings do not support the hypothesis that allergen exp osure in asthma results in immediate release of endothelin. However, r elease at later time-points and a role for endothelin in late-phase br onchoconstriction me not excluded.