AEROSOLIZED AND INTRAVENOUSLY ADMINISTERED LEUKOTRIENES - EFFECTS ON THE BRONCHOCONSTRICTOR POTENCY OF HISTAMINE IN THE GUINEA-PIG

Abstract

The effects of leukotrienes C4 and D4 (LTC4 and LTD4), administered intravenously or by aerosol, on the bronchoconstrictor potency of intravenously administered histamine have been investigated in anaesthetized, mechanically ventilated guinea-pigs. LTC4 (2 nM) had no effect on either the EC50 or the maximum contractile response to histamine on the isolated trachea of the guinea-pig. At 10 nM, LTC4 induced a rightward shift in the histamine concentration-response curve without affecting the maximum response. LTD4 (0.05-0.20 nmol kg-1, i.v.) dose-dependently enhanced histamine (9-36 nmol kg-1, i.v.)-induced increases in airways resistance, whereas equibronchoconstrictor doses of LTC4 (0.1-0.4 ..