Biological activities of prostaglandin H1 analogs.

The influences of epoxymethano and epoxycarbonyl analogs of PGH1 on washed rabbit platelets, isolated smooth muscles and perfused heart preparations were investigated. On washed rabbit platelets, 11,9-epoxymethano and 11,9-epoxycarbonyl PGH1 produced a platelet aggregation whereas 9,11-epoxymethano and 9,11-epoxycarbonyl PGH1 produced an inhibition of arachidonic acid-induced platelet aggregation. On iso-ated rabbit thoracic aorta strips, 9,11-epoxycarbonyl PGH1 showed strong contracting activity (5 times as active as 11,9-epoxymethano PGH2 and 31 times as active as PGH2). All the analogs of PGH1 caused contraction of guinea pig tracheal muscle and caused an increase of perfusion pressure in guinea pig heart, though 11,9-epoxymethano and epoxycarbonyl PGH1 were far more active than 9,11-epoxymethano and epoxycarbonyl PGH1. Differences in biological activities between 11,9-epoxymethano and epoxycarbonyl PGH1 indicate that the orientation of functional groups at C9 and C11 influences biological activities.