title: Prostaglandin F2 stimulates the generation of lipoxygenase products in guinea pig isolated trachea.
abstract: The generation of lipoxygenase products on the contraction elicited by prostaglandin (PG) F2 alpha was investigated in the guinea-pig isolated trachea. Indomethacin (5 x 10(-6) M) inhibited the response at low concentrations of PGF2 alpha while enhanced the response at higher concentrations of PGF2 alpha. Phenidone (10(-4) M) and nordihydroguaiaretic acid (NDGA, 3 x 10(-5) M) appeared to inhibit the PGF2 alpha response. The PGF2 alpha response augmented by indomethacin was dose-dependently inhibited by NDGA and a leukotriene (LT) antagonist, FPL55712. NDGA had no effect on the contraction elicited by histamine but markedly inhibited the contraction elicited by LTD4. The inhibition by NDGA of the LTD4-induced contraction was abolished in the presence of indomethacin (5 x 10(-6) M). FPL55712 inhibited the LTD4-induced contraction but the extent of the antagonism was not changed by indomethacin. In the presence of indomethacin PGF2 alpha (10(-8) M) did not affect the LTD4 (3 x 10(-9) M) response but significantly enhanced the arachidonic acid (AA, 6.6 x 10(-5) M)-induced contraction. FPL55712 (3 x 10(-6) M) completely inhibited the AA response augmented by PGF2 alpha. These results suggest that lipoxygenase-mediated LT-like substances are released in the response at higher concentrations of PGF2 alpha on the guinea-pig isolated trachea, and the mode of action of PGF2 alpha is different from those of histamine and LTD4.
mesh_terms: D000818:Animals; D002867:Chromones / Q000494:pharmacology; D006168:Guinea Pigs / Q000378:metabolism*; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008084:Lipoxygenase / Q000096:biosynthesis*; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D011460:Prostaglandins F / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology; D013189:SRS-A / Q000037:antagonists & inhibitors; D014132:Trachea / Q000378:metabolism*
chemical_list: D002867:Chromones; D011460:Prostaglandins F; D011720:Pyrazoles; D013189:SRS-A; D009637:Masoprocol; C006312:FPL 55712; D008084:Lipoxygenase; C015429:phenidone; D007213:Indomethacin