ABSTRACT
3-Hydroxy-5-trifluoromethyl-N-(2-(2-thienyl)-2-phenyl-ethenyl)- benzo (b) thiophene-2-carboxamide (L-652,343) is an inhibitor of cyclooxygenase and 5-lipoxygenase in vitro and inhibits the synthesis of the products of both these pathways in whole cells. L-652,343 is an inhibitor of the acute edema induced by carrageenan in vivo and is active topically in suppressing arachidonic acid induced inflammation in the skin. The compound is an effective inhibitor of the chronic inflammation of adjuvant and type II collagen induced polyarthritis. L-652,343 is an extremely potent analgesic in models of yeast and platelet activating factor induced hyperalgesia in rats and phenylbenzoquinone-induced writhing in mice. The fever induced by Brewer's yeast is lowered by L-652,343. The ulcerogenicity and gastric bleeding induced by L-652,343 is extremely low, providing a favorable therapeutic index which is superior to that of indomethacin, piroxicam and phenylbutazone.
Subject(s)
Arachidonate Lipoxygenases/antagonists & inhibitors , Cyclooxygenase Inhibitors , Lipoxygenase Inhibitors , Thiophenes/pharmacology , Analgesics , Animals , Anti-Inflammatory Agents , Anti-Inflammatory Agents, Non-Steroidal , Dogs , Female , Male , Mice , Mice, Inbred Strains , Rats , Rats, Inbred Strains , Stomach Ulcer/chemically induced , Thiophenes/toxicityABSTRACT
Treatment of intact human platelets with the tumour-promoting phorbol ester, phorbol 12-myristate 13-acetate (PMA), specifically inhibited PGD2-induced cyclic AMP formation without affecting the regulation of cyclic AMP metabolism by PGI2, PGE1, 6-keto-PGE1, adenosine or adrenaline. This action of PMA was: (i) concentration-dependent; (ii) not mediated by evoked formation or release of endogenous regulators of adenylate cyclase activity (thromboxane A2 or ADP); (iii) mimicked by 1,2-dioctanoylglycerol (DiC8) but not by 4 alpha-phorbol 12,13-didecanoate (which does not activate protein kinase C); (iv) attenuated by Staurosporine. These results indicate that activation of protein kinase C in platelets may provide a regulatory mechanism to abrogate the effects of the endogenous adenylate cyclase stimulant PGD2 without compromising the effects of exogenous stimulants of adenylate cyclase (PGI2, 6-keto-PGE1, adenosine).
