Characterization of Thromboxane A₂/Prostaglandin H₂ Receptors in Porcine Coronary Artery -The Inhibitory Effect of a Novel Dibenzoxepin Derivative, KW-3635

Summary

We characterized the thromboxane A₂/prostaglandin H₂ receptors in porcine coronary artery. The binding of [³H]SQ 29,548, a thromboxane A₂ antagonist, to coronary arterial membranes was saturable and displaceable. Scatchard analysis of equilibrium binding showed a single class of high affinity binding sites with a dissociation constant of 18.5 ±1.0 nM and the maximum binding of 80.7 ± 5.2 fmol/mg protein. [³H]SQ 29,548 binding was concentration-dependently inhibited by thromboxane A₂ antagonists such as SQ 29,548, BM13505 and BM13177 or the thromboxane A₂ agonists such as U46619 and U44069. KW-3635, a novel dibenzoxepin derivative, concentration-dependently inhibited the [³H]SQ 29,548 binding to thromboxane A₂/prosta-glandin H₂ receptors in coronary artery with an inhibition constant of 6.0 ± 0.69 nM (mean ± S.E.M.).

• References

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