Influence of aminophylline and ketotifen in comparison to the lipoxygenase inhibitors NDGA and esculetin and the PAF antagonists WEB 2170 [correction of 2107] and BN 52021 on endothelin-1 induced vaso- and bronchoconstriction.

Theophylline (p less than 0.05) and ketotifen (p greater than 0.05) markedly reduced, but the lipoxygenase inhibitors and PAF receptor antagonists were without any influence on the endothelin-1 (ET-1 1 nmol/kg i.v.) induced increase of pulmonary inflation pressure of anaesthetised and ventilated guinea-pigs. The ET-1 induced increase in mean arterial blood pressure as well as the secondary TXB2 release into bronchoalveolar lavage fluid or plasma was not decreased. TXB2 release cannot be the only mechanism of bronchopulmonary ET-1 effects in guinea-pigs in vivo.