Potentiation of bradykinin-induced responses by indomethacin in the intactand denuded epithelium of guinea pig tracheal preparations

We studied the effect of indomethacin, a cyclooxygenase inhibitor, on brady kinin-induced responses in the intact and denuded epithelium of the isolate d tracheal smooth muscle in guinea pigs. Epithelium removal alone did not a lter the responsiveness to bradykinin. Indomethacin (2.8 mu M) enhanced the sensitivity to bradykinin of both intact and denuded preparations. This fi nding suggests that the tracheal epithelial may have no protective effect o n the contractile responses induced by bradykinin. This may be due to the p resence of high amounts of bradykinin-inactivating enzymes in the tracheal smooth muscle. Indomethacin-medicated potentiation caused by bradykinin in epithelium intact and denuded preparations may be an indication of removal of the bronchodilator prostaglandin biosynthesis. The significance of these findings is discussed.