A Thromboxane A₂-Antagonistic Effect of Pyridinolcarbamate and Phthalazinol

Thromboxane A21)-3> (TXA2) has been known to induce a dramatic arterial constriction in which platelets participate and characteristically leads to arterial spasm. The arterial spasm is postulated to initiate variant angina, myocardial infarction, sudden cardiac death, and stroke.l)-4) Among substances synthetized by Shimamoto and Ishikawa as the inhibitor against the edematous reaction of rabbit aorta, the authors discovered phthalazinol (E G626) and pyridinolcarbamate (PD C) , which show a highly potent, reversible and competitive antagonistic effect on TXA2 in its contracting effect on the artery. Their anti-TXA2 activity in vitro on the contractive effect of TXA2 on rabbit aortic stripsl) superfused by Krebs solution has been subjected to the present publication.