Thromboxane A2 receptor antagonism in man and rat by a sulphonylcyanoguanidine (BM-144) and a sulphonylurea (BM-500).
Torasemide, a loop diuretic, has been reported to relax dog coronary artery precontracted by thromboxane A2 (TXA2), an endogenous prostanoid involved in cardiovascular and pulmonary diseases. N-cyano-N'-[[4-(3'-methylphenylamino)pyrid-3-yl]sulphonyl] homopiperidinoamidine (BM-144) and N-isopropyl-N'-[5-nitro-2-(3'-methylphenylamino)-benzenesulphon yl]urea (BM-500), chemically related to torasemide, have been examined for their TXA2 antagonism. The affinity (IC50, the concentration resulting in 50% inhibition) of BM-144 and BM-500 for the TXA2 receptor of washed platelets from man was 0.28 and 0.079 microM, respectively. This is better than for sulotroban (IC50 = 0.93 microM) but less than for SQ-29548 (IC50 = 0.021 microM), two TXA2 antagonists used as reference. The aggregation of platelets from man induced by arachidonic acid was prevented by BM-144 (IC50 = 9.0 microM) and by BM-500 (IC50 = 14.2 microM). Similar results were obtained by use of U-46619, a TXA agonist, as aggregating agent (BM-144, IC50 = 12.9 microM and BM-500, IC50 = 9.9 microM). The contracting effect of U-46619 on rat stomach strip was abolished by BM-144 (IC50 = 1.01 microM) and BM-500 (IC50 = 2.54 microM). Both drugs (BM-144: IC50 = 0.12 microM and BM-500: IC50 = 0.19 microM) also relaxed rat aorta precontracted by U-46619; both were more potent than sulotroban (IC50 = 1.62 microM). The two torasemide derivatives (100 microM) did not significantly affect the myo-stimulating effect of some prostaglandins (PGE2, PGI2, PGF2alpha) or aorta contraction elicited by KCl (30 mM). They did not modify rat diuresis after administration of a 30-mg kg(-1) dose. In conclusion, BM-144 and BM-500 can be regarded as novel non-carboxylic TXA2 receptor antagonists and offer a novel template for the design of more potent molecules.
Masereel
B
B
Department of Pharmacy, University of Namur, FUNDP, Belgium.
Damas
J
J
Fontaine
J
J
Lembege
M
M
Lacan
F
F
Nuhrich
A
A
Delarge
J
J
Pochet
L
L
Dogne
J M
JM
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006801:Humans; D006834:Hydrazines / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017482:Receptors, Thromboxane / Q000037:antagonists & inhibitors*; D013449:Sulfonamides / Q000494:pharmacology*; D013453:Sulfonylurea Compounds / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects
C120544:BM 144; C121719:BM 500; D019086:Bridged Bicyclo Compounds, Heterocyclic; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D017482:Receptors, Thromboxane; D013449:Sulfonamides; D013453:Sulfonylurea Compounds; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C045749:SQ 29548