L-655,240

Inhibition of platelet-activating factor induced renal hemodynamic and tubular dysfunctions with L-655,240, a new thromboxane-prostaglandin endoperoxide antagonist.[Pubmed:2758373]

Can J Physiol Pharmacol. 1989 Apr;67(4):304-8.

The continuous infusion or bolus injection of the platelet-activating factor (PAF) is associated with profound hypotension, marked reductions of renal plasma flow, glomerular filtration, and urinary sodium excretion. All these effects are inhibited by blocking PAF receptors. To examine further the potential mediators of PAF on renal function, we utilized L-655,240 (6 mg/kg, intravenously), a thromboxane-prostaglandin endoperoxide antagonist, to study the systemic and renal response to PAF (0.8 micrograms/kg, intravenously) in the anesthetized dog, using clearance methodology. PAF decreased blood pressure from 115 +/- 7 to 54 +/- 4 mmHg (1 mmHg = 133.3 Pa), renal plasma flow from 105 +/- 6 to 74 +/- 56 mL/min, and glomerular filtration from 43 +/- 3 to 32 +/- 1 mL/min. PAF also reduced urine volume from 1.1 +/- 0.2 to 0.4 +/- 0.1 mL/min, and urinary sodium from 158 +/- 7 to 86 +/- 7 mu equiv./min. L-655,240 alone had no significant effect on blood pressure, renal plasma flow, and filtration rate, at any dose. However, the 6-mg/kg dose resulted in a slight elevation of diuresis, from 1.1 +/- 0.2 to 1.9 +/- 0.1 mL/min, and urinary sodium, from 134 +/- 13 to 212 +/- 19 mu equiv./min. All doses of L-655,240 blocked the effect of PAF on blood pressure. However, the two lower doses of this antagonist (1 and 3 mg/kg) failed to prevent the PAF-induced fall of renal plasma flow and filtration rate, and attenuated the effect on urinary sodium in a dose-dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacology of L-655,240 (3-[1-(4-chlorobenzyl)-5-fluoro-3-methyl-indol-2-yl]2,2-dimethylpro pan oic acid); a potent, selective thromboxane/prostaglandin endoperoxide antagonist.[Pubmed:3582493]

Eur J Pharmacol. 1987 Mar 17;135(2):193-201.

L-655,240 (3-[1-(4-chlorobenzyl)-5-fluoro-3-methyl-indol-2-yl]2,2-dimethylpropa noic acid) has been studied in vitro on the guinea-pig tracheal chain, pulmonary artery and thoracic aorta ring and shown to be a potent, competitive antagonist of contractions induced by the prostaglandin endoperoxide analogue, U-44069 (pA2 values 8.0, 8.4 and 8.0 respectively). Selectivity on the guinea-pig trachea was indicated by non-competitive antagonism of contractions induced by prostaglandin D2 and minimal activity against contractions induced by leukotriene D4, prostaglandin F2 alpha, serotonin, histamine and acetylcholine. L-655,240 was a potent inhibitor of the aggregation of washed human platelets induced by U-44069 (IC50 value 7 X 10(-9) M) and inhibited aggregation of human platelet rich plasma induced by U-44069, U-46619, thromboxane A2 and collagen but not ADP or platelet activating factor. In vivo i.v. L-655,240 administered to guinea-pigs inhibited bronchoconstriction induced by i.v. U-44069 and arachidonic acid (ED50 values 0.09 and 0.23 mg kg-1) but not histamine, acetylcholine or serotonin. When administered to rhesus monkeys (3 and 10 mg/kg p.o.), L-655,240 inhibited ex vivo platelet aggregation induced by U-44069 but not ADP. It is concluded that L-655,240 is a potent, selective, orally active thromboxane/prostaglandin endoperoxide antagonist.

PAF increases vascular permeability in selected tissues: effect of BN-52021 and L-655,240.[Pubmed:3238010]

Prostaglandins. 1988 Nov;36(5):631-44.

The effect of the potent inflammatory mediator, platelet activating factor (PAF) was studied on the vascular permeability of selected rat tissues using the extravasation of Evans blue dye (EB) as a marker. EB (20 mg/kg) was injected in the caudal vein together with increasing doses of PAF (0.1, 1.0 and 5.0 micrograms/kg). The animals were killed and the dye was extracted in selected organs using formamide (4 ml/g wet weight tissues) and the content was expressed as EB micrograms/g dry weight. Extravasation of EB varied markedly from one tissue to another and increased as a function of time (from 0 to 60 min). PAF (5.0 micrograms/kg) increased the pancreas and duodenum vascular permeability by 15 and 5 fold respectively. At the doses of 0.1 and 1.0 microgram/kg, PAF induced a slight increase (P less than 0.01) of the vascular permeability of the heart 5 min after the injection. The PAF antagonist BN-52021 (2 and 10 mg/kg) produced a dose-dependent inhibition of the PAF effects on the pancreas, heart and duodenum. Maximum inhibition (approximately 100%) was achieved at the dose of 10 mg/kg. This antagonist given in the absence or the presence of PAF reduced the lung plasma extravasation below control levels. A thromboxane antagonist, L-655,240 (1.0 and 5.0 mg/kg) also inhibited PAF-induced increases in vascular permeability in heart, duodenum and pancreas. It also reduced below control levels the EB extravasation in kidneys, spleen and lungs. Maximum inhibition (50% for the duodenum, and 40% for the pancreas) was achieved at the dose of 5.0 mg/kg.

Interspecies differences in thromboxane receptors: studies with thromboxane receptor antagonists in rat and guinea pig smooth muscles.[Pubmed:1531361]

J Pharmacol Exp Ther. 1992 Feb;260(2):789-94.

To investigate possible subclasses of thromboxane receptors in vascular and airways smooth muscles, we evaluated activities of five structurally different competitive thromboxane receptor antagonists (i.e., SQ 29,548 [( 1S-[1 alpha, 2 alpha(5Z), 3 alpha, 4 alpha]]-7-[3- [2- [(phenylamino)carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1] hept-2-yl]-5-heptenoic acid), L655,240 (3-[1-(4-chlorobenzyl)-5- fluoro-3-methylindol-2yl]2,2-dimethyl propanoic acid), BM 13,505 (4-[2-[[(4-chlorophenyl)sulfonyl]amino]ethyl]benzeneacetic acid), GR 32,191 [( 1R-[1 alpha (Z), 2 beta, 3 beta, 5 alpha]]-(+)-7- [5-[[(1, 1'-biphenyl)-4-yl]methoxy]-3-hydroxy-2-(1- piperidinyl)cyclopentyl]-4-heptenoic acid hydrochloride] and SQ 30,741 [1S- [1 alpha,2 alpha(5Z),3 alpha,4 alpha]]- 7[[[[[( oxaheptyl)amino]acetyl]amino]methyl]- 7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid)] in trachea, aorta and portal vein from both rats and guinea pigs. Schild plots and drug receptor dissociation constants (KB) were determined for each antagonist in each tissue using U-46,619 as the agonist. Rank orders of potency were identical in rat aorta, rat trachea and rat portal vein (SQ 29,548 greater than L 655,240 greater than BM 13,505 greater than GR 32,191 greater than SQ 30,741), with calculated KB values ranging from 0.5 to 20 nM. Rank orders of potency in guinea pig trachea and guinea pig portal vein were the same (GR 32,191 greater than SQ 29,548 greater than SQ 30,741 greater than L 655,240 greater than BM 13,505), with KB values ranging from 0.1 to 30 nM.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of L655,240, a selective thromboxane and prostaglandin endoperoxide antagonist, on ischemia- and reperfusion-induced cardiac arrhythmias.[Pubmed:2464097]

J Cardiovasc Pharmacol. 1988 Sep;12(3):264-71.

The purpose of this investigation was to provide a detailed analysis of the effects of the thromboxane antagonist L655,240 (0.3 mg/kg i.v.) on early ischemia- and reperfusion-induced arrhythmias in a canine model of coronary artery occlusion. In a dose that abolished the pulmonary response to U46619, L655,240 attenuated markedly the severity of those arrhythmias that resulted from reperfusion of the myocardium; survival from the combined occlusion-reperfusion insult was increased from 10% in control animals to 70% in dogs administered L655,240. Drug intervention did not significantly alter the total number of arrhythmias during the period of ischemia, but a detailed analysis of the different types of arrhythmia that occurred during this period showed that L655,240 significantly reduced those arrhythmias in phase 1a (0-10 min of occlusion) without affecting the later phase 1b arrhythmias. This was particularly shown in the marked reduction in the number of salvos (couplets and triplets) during this period. Neither those arrhythmias occurring later in the ischaemia period (phase 1b) nor the total number of single ectopics and salvos or the incidence and duration of ventricular tachycardia was modified by L655,240. These results reveal that thromboxane antagonism protects especially against reperfusion-induced ventricular fibrillation and against early (phase 1a) ischemia-induced arrhythmias, possibly implicating a role for thromboxane in the genesis of these cardiac rhythm disturbances.