RT Journal Article SR Electronic T1 Endothelin-1 levels in induced sputum samples from asthmatic and normal subjects. JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 625 OP 627 DO 10.1136/thx.52.7.625 VO 52 IS 7 A1 G W Chalmers A1 L Thomson A1 K J Macleod A1 K D Dagg A1 B J McGinn A1 C McSharry A1 K R Patel A1 N C Thomson YR 1997 UL http://thorax.bmj.com/content/52/7/625.abstract AB 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 saliva, induced sputum, and plasma from asthmatic and non-asthmatic subjects were compared. METHODS: Sputum induction was performed on 28 asthmatic subjects and nine normal volunteers. ET-1 levels were measured in plasma, saliva, and sputum samples and reversed phase high performance liquid chromatography (RP-HPLC) was performed on saliva and sputum samples. RESULTS: ET-1 was present in the following order of concentration 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 differences between asthmatic and normal subjects in the levels of ET-1 in each fluid. The levels of ET-1 in asthmatic subjects were not influenced by whether or not they were taking inhaled steroids. RP-HPLC of sputum and saliva confirmed the presence of ET-1 in these fluids. CONCLUSIONS: 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 plasma between normal subjects and asthmatics without bronchoconstriction, it is apparent that ET-1 is produced or released locally within the respiratory tract in concentrations higher than those in plasma.