Effects of pulmonary metabolites of prostaglandins E2 and F2alpha on guinea-pig respiratory tract

Abstract

The effects of three pulmonary metabolites of prostaglandins E2 and F2alpha on the guinea-pig tracheal muscle in vitro and on lung resistance in vivo were investigated. Prostaglandin F2alpha, 13,14-dihydro PGF2alpha and 13,14-dihydro 15-oxo PGF2alpha produced contractions on the tracheal muscle in vitro. 15-oxo PGF2alpha relaxed some tracheal preparations but stimulated others, the stimulant action having a threshold dose range some 10-25 times lower than the relaxant doses. Prostaglandin F2alpha and 13,14-dihydro PGF2alpha increased lung resistance in anaesthetized guinea-pigs. Prostaglandin E2 and its three pulmonary metabolites produced relaxation of guinea pig trachea in vitro and decreased lung resistance in vivo. All three metabolites were less active than PGE2 in both the systems. The in vitro effects of PGF2alpha and its metabolites were selectively blocked by polyphloretin phosphate.