ENDOTHELIN IN BRONCHIAL BIOPSY SPECIMENS FROM HORSES WITH RECURRENT AIRWAY OBSTRUCTION

Recurrent airway obstruction (RAO) is a chronic, worldwide recognized diseases of horses. Despite the well known clinical presentation and the ease of diagnosis, the exact etiology and pathogenesis are still unclear which makes it difficult prevention and treatment. Recurrent obstruction of airway is caused by mucus production, bronchospasm and bronchial edema and the most important clinical signs are chronic cough and expiratory effort. ET-1 is the most potent vasoconstrictor molecule up to now identified, produced by several cells as endothelial cells, smooth muscle cells and epithelial cells of airways. ET-1 is a potent proinflammatory, secretagogues and bronchoconstrictors mediator. ET-1 can cause bronchial contraction on bronchial rings of horses in vitro, , especially in horse with respiratory disease. A previous work demonstrated the presence of endothelin-1 (ET-1) in bronchial biopsy of healthy horses, while in the present one, the results of immunohistochemical analysis of bronchial biopsy sampled from horses affected by reurrent airway obstruction are presented and compared with healthy horses. Histological samples from horse with RAO have a much more intense reaction for ET-1, especially epithelial cells. These results confirmed the involvement of ET-1 in pathogenesis of respiratory condition of horse and the possible use of its receptors as pharmacological target.