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. 1986 Mar;87(3):543–551. doi: 10.1111/j.1476-5381.1986.tb10196.x

Prostaglandin endoperoxide analogues which are both thromboxane receptor antagonists and prostacyclin mimetics.

R A Armstrong, R L Jones, J MacDermot, N H Wilson
PMCID: PMC1916575  PMID: 3026540

Abstract

Two prostaglandin endoperoxide analogues, EP 035 and EP 157, behave as specific thromboxane receptor antagonists on isolated smooth muscle preparations such as rabbit aorta, dog saphenous vein and guinea-pig trachea. However, in human platelet-rich plasma (PRP) they produce an unsurmountable block of aggregation induced by a wide range of agents (ADP, platelet-activating factor, thrombin); this inhibitory profile is typical of that seen with either prostaglandin I2 (PGI2) or PGD2. EP 035 and EP 157 induce large increases in cyclic AMP levels (up to 20 times basal) in human PRP. Simultaneous exposure to PGE1 markedly reduces their effect on cyclic AMP; exposure to PGD2 is much less effective in this respect. The adenylate cyclase inhibitor SQ 22,536 opposes the inhibitory action of EP 035, EP 157, iloprost (a stable PGI2 analogue) and PGD2 on platelet aggregation. However, the xanthone derivative AH 6809 blocks the inhibitory action of PGD2 but does not affect EP 035, EP 157 and PGI2 and its structural analogues. EP 035 and EP 157 displace [3H]-iloprost binding to the PGI2 receptor on human platelet membranes. Displacing ability is ranked as follows: iloprost greater than 6a-carba PGI2 greater than EP 157 greater than EP 035 greater than EP 164 (alpha-dinor derivative of EP 157). This order of potency is the same as that found for activation of adenylate cyclase in homogenates of washed human platelets and for inhibition of aggregation in washed human platelets. The activities of EP 035 and EP 157 were studied in two other systems containing PGI2 receptor-adenylate cyclase complexes, the NCB-20 cell line and human lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

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Selected References

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