['To investigate the reactivity of intrapulmonary arterial rings to vasoactive substances as thromboxane A2 and endothelin-1 in patients with chronic obstructive pulmonary disease (COPD).', 'Intrapulmonary arterial rings isolated from patients with normal lung function and COPD were mounted in a Multi Myograph system to determine the reactivity of the intrapulmonary arterial rings to 60 mmol/L KCl, thromboxane A2 analogue U46619 and endothelin-1 before and after preconditioning with the COX synthase inhibitor indomethacin.', 'The reactivity of intrapulmonary arterial rings to U46619 and endothelin-1 was significantly decreased in patients with COPD. The reactivity to U46619 was dramatically decreased in patients with normal lung function after application of indomethacin.'] Is [ Reactivity of intrapulmonary arterial rings to thromboxane A2 and endothelin-1 reduced in patients with chronic obstructive pulmonary disease ]?