[The role of cyclooxygenase products on bronchial responsiveness to methacholine in patients with sino-bronchial syndrome].

The role of cyclooxygenase products on bronchial responsiveness to methacholine was studies in 9 patients with sino-bronchial syndrome. Provocative concentrations of methacholine, producing a 20% fall in forced expiratory volume in one second (FEV1)(PC20-FEV1) and a 35% fall in inverse respiratory resistance (Grs) (PC35-Grs), were measured before and after oral administration of a thromboxane synthetase inhibitor (OKY-046) and a cyclooxygenase inhibitor (indomethacin). Baseline values of FEV1 and respiratory resistance (Rrs) were not altered by OKY-046 or indomethacin. Geometric mean values of PC20-FEV1 and PC35-Grs were significantly (p less than 0.005 and p less than 0.05) increased from 2.19 mg/ml (GSEM, 1.58) and 0.79 mg/ml (GSEM, 1.70) to 8.13 mg/ml (GSEM, 1.92) and 1.55 mg/ml (GSEM, 1.38) by indomethacin, whereas these values were not significantly increased by OKY-046. These findings indicate that not thromboxane A2 but bronchoconstricting prostaglandins may play a role in bronchial hyperresponsiveness in sino-bronchial syndrome.