Thromboxane A2 could be involved in bronchial hyperresponsiveness to methacholine in asthmatic subjects but not in bronchitic subjects |
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Authors: | M Fujimura S Sakamoto Y Kamio K Nishi M Saito Y Miyake M Nomura T Matsuda |
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Affiliation: | Third Department of Internal Medicine, Kanazawa University School of Medicine, Japan. |
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Abstract: | To determine whether the involvement of thromboxane A2 in bronchial hyperresponsiveness is specific to asthma, we examined the effects of a selective thromboxane synthetase inhibitor (OKY-046) and a cyclooxygenase inhibitor (indomethacin) on bronchial responsiveness to methacholine in patients with bronchial asthma and chronic bronchitis. The provocative concentration of methacholine producing a 20% fall in forced expiratory volume in one second (PC20-FEV1) was measured before and after oral administration of OKY-046 and indomethacin in eight asthmatic and 10 bronchitic subjects. Baseline FEV1 value was not altered by OKY-046 or indomethacin. The geometric mean value of PC20-FEV1 increased significantly (p less than 0.005) from 1.78 to 4.27 mg/ml after OKY-046 in asthmatic subjects, but not in bronchitic subjects. On the other hand, PC20-FEV1 was not altered by indomethacin in all subjects. It was concluded that the involvement of thromboxane A2 in bronchial hyperresponsiveness may be specific to asthma. |
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