ENDOTHELIN-1 LEVELS IN INDUCED SPUTUM SAMPLES FROM ASTHMATIC AND NORMAL SUBJECTS

Background - Endothelin-1 (ET-1) is a potent bronchoconstrictor which may have a role in the pathogenesis of asthma. The levels of ET-1 in s aliva, induced sputum, and plasma from asthmatic and nonasthmatic subj ects were compared. Methods - Sputum induction was performed on 28 ast hmatic subjects and nine normal volunteers. ET-1 levels were measured in plasma, saliva, and sputum samples and reversed phase high performa nce Liquid chromatography (RP-HPLC) was performed on saliva and sputum samples. Results - ET-1 was present in the following order of concent ration in both normal and asthmatic subjects: saliva > sputum > plasma (saliva, median 30.1 and 23.9 pg/ml, respectively; sputum, median 15. 5 and 11.2 pg/ml; plasma, median 3.1 and 3.6 pg/ml). There were no dif ferences between asthmatic and normal subjects in the levels of ET-1 i n each fluid. The levels of ET-1 in asthmatic subjects were not influe nced by whether or not they were taking inhaled steroids. RP-HPLC of s putum and saliva confirmed the presence of ET-1 in these fluids. Concl usions - Levels of ET-1 can be measured in saliva and sputum obtained by sputum induction in asthmatic and healthy subjects and, although no difference was found in basal levels of ET-1 in sputum, saliva and pl asma between normal subjects and asthmatics without bronchoconstrictio n, it is apparent that ET-1 is produced or released locally within the respiratory tract in concentrations higher than those in plasma.