Pharmacological actions of SQ 29,548, a novel selective thromboxane antagonist.
SQ 29,548, [1S-[1 alpha,2 beta (5Z),3 beta,4 alpha]-7-[3-[[2-[(phenylamino) carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1] hept-2-yl]-5-heptenoic acid, and the racemic modification, +/- SQ 29,548, were identified as active inhibitors of human platelet aggregation induced by arachidonic acid, collagen, epinephrine (2 degrees phase) and the thromboxane A2 mimics, 9,11-azo prostaglandin (PG) H2 and 11,9-epoxymethano PGH2. SQ 29,548 did not inhibit aggregation induced by ADP, and it did not prevent PGD2 from inhibiting ADP-induced platelet aggregation. Inhibition of platelet function by +/- SQ 29,548 was not associated with inhibition of cyclooxygenase or thromboxane synthetase or with changes in platelet cyclic AMP. In guinea-pig trachea and rat aorta, +/- SQ 29,548 competitively antagonized the activity of 9,11-azo PGH2 with pA2 values of 7.8 and 8.4, respectively. The chiral compound, SQ 29,548 competitively antagonized contractions of guinea-pig tracheal spirals caused by 11,9-epoxymethano PGH2 with a pA2 value of 9.1. The +/- SQ 29,548 competitively antagonized tracheal responses to 11,9-epoxymethano PGH2 and PGD2 with pA2 values of 8.2 and 8.3, respectively, indicating that PGD2 and the thromboxane A2 mimic probably act at the same receptor in guinea-pig tracheal smooth muscle. Contractions of guinea-pig tracheal spirals induced by PGE2 were not antagonized, and those caused by PGF2 alpha were only partially antagonized by +/- SQ 29,548. The +/- SQ 29,548 also significantly inhibited the aorta contracting activity of 11,9-epoxymethano PGH2 (pA2 = 9.1) and thromboxane A2 released from perfused guinea-pig lungs upon arachidonic acid challenge.(ABSTRACT TRUNCATED AT 250 WORDS)
D000262:Adenylyl Cyclases / Q000032:analysis; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004305:Dose-Response Relationship, Drug; D005231:Fatty Acids, Unsaturated; D006168:Guinea Pigs; D006801:Humans; D006834:Hydrazines / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D013237:Stereoisomerism; D013270:Stomach / Q000187:drug effects; D013928:Thromboxane A2 / Q000037:antagonists & inhibitors*; D013931:Thromboxanes / Q000037:antagonists & inhibitors*; D014132:Trachea / Q000187:drug effects
D001095:Arachidonic Acids; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D013931:Thromboxanes; D016718:Arachidonic Acid; D013928:Thromboxane A2; C045749:SQ 29548; D000262:Adenylyl Cyclases