sm-19712 and phosphoramidon

Circulating levels of endothelin (ET)-1 and endogenous ET(A)-mediated constriction are increased in human aging. The mechanisms responsible are not known.. Investigate the storage, release, and activity of ET-1 system in arteries from young and aged Fischer-344 rats.. After NO synthase inhibition (L-NAME), thrombin contracted aged arteries, which was inhibited by endothelial denudation, ET(A) receptor antagonism (BQ123), and ECE inhibition (phosphoramidon, SM19712) or by inhibiting exocytosis (TAT-NSF, N-ethylmaleimide-sensitive factor inhibitor). Thrombin did not cause endothelium-dependent contraction of young arteries. In aged but not young arteries, thrombin rapidly increased ET-1 release, which was abolished by endothelium denudation or TAT-NSF. L-NAME did not affect ET-1 release. ET-1 immunofluorescent staining was punctate and distinct from von Willebrand factor (VWF). VWF and ET-1 immunofluorescent intensity was similar in young and aged quiescent arteries. Thrombin rapidly increased ET-1 staining and decreased VWF staining in aged but had no effect in young aortas. After L-NAME, thrombin decreased VWF staining in young aortas. NO donor DEA-NONOate (1 to 100 nmol/L) reversed thrombin-induced exocytosis in young (VWF) but not aged L-NAME-treated aortas (VWF, ET-1). Expression of preproET-1 mRNA and ECE-1 mRNA were increased in aged compared to young endothelium. BigET-1 levels and contraction to exogenous BigET-1 (but not ET-1) were also increased in aged compared to young arteries.. The stimulated exocytotic release of ET-1 is dramatically increased in aged endothelium. This reflects increased reactivity of exocytosis, increased expression and storage of ET-1 precursor peptides, and increased expression of ECE-1. Altered endothelial exocytosis of ET-1 and other mediators may contribute to cardiovascular pathology in aging.

Topics: Age Factors; Aging; Animals; Aorta, Thoracic; Aspartic Acid Endopeptidases; Dose-Response Relationship, Drug; Endothelin A Receptor Antagonists; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Exocytosis; Fluorescent Antibody Technique; Glycopeptides; Hydrazines; In Vitro Techniques; Mesenteric Arteries; Metalloendopeptidases; N-Ethylmaleimide-Sensitive Proteins; NG-Nitroarginine Methyl Ester; Nitric Oxide Donors; Nitric Oxide Synthase; Peptides, Cyclic; Rats; Rats, Inbred F344; Receptor, Endothelin A; RNA, Messenger; Sulfonamides; Sulfonylurea Compounds; Thrombin; Up-Regulation; Vasoconstriction; von Willebrand Factor

Endothelin-1 and norepinephrine are involved in myocardial ischemia/reperfusion injury. The aim of this study was to investigate the role of endogenously generated endothelin-1 in ischemia/reperfusion-induced norepinephrine overflow and cardiac dysfunction using a nonselective prototype of endothelin-converting enzyme (ECE) inhibitor, phosphoramidon, and a selective ECE inhibitor, SM-19712 (4-chloro-N-[[(4-cyano-3-methyl-1-phenyl-1H-pyrazol-5-yl)amino]carbonyl]benzenesulfonamide, monosodium salt). According to the Langendorff technique, isolated Sprague-Dawley rat hearts were subjected to 40-min global ischemia followed by 30-min reperfusion. Phosphoramidon and SM-19712 were perfused 30 min before ischemia and during reperfusion. Endothelin-1 level in left ventricle was increased by ischemia/reperfusion. This increase in left ventricular endothelin-1 level was suppressed by treatment with SM-19712. SM-19712 significantly improved ischemia/reperfusion-induced cardiac dysfunction such as decreased left ventricular developed pressure and dP/dt(max) and increased left ventricular end diastolic pressure. In addition, this agent suppressed excessive norepinephrine overflow in the coronary effluent from the post-ischemic heart. In contrast, treatment with phosphoramidon further enhanced left ventricular endothelin-1 level and norepinephrine overflow, and significantly worsened cardiac dysfunction after ischemia/reperfusion. These responses such as exaggerated norepinephrine overflow and the cardiac dysfunction observed after ischemia/reperfusion were markedly suppressed in the presence of a selective endothelin ET(A) receptor antagonist, ABT-627 [2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N,N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid]. These findings indicate that cardiac endothelin-1 production is enhanced by ischemia/reperfusion, and this endogenously increased endothelin-1 is involved in post-ischemic norepinephrine overflow and cardiac dysfunction via the activation of endothelin ET(A) receptors.

Topics: Animals; Aspartic Acid Endopeptidases; Atrasentan; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Glycopeptides; Male; Metalloendopeptidases; Myocardial Ischemia; Myocardial Reperfusion Injury; Norepinephrine; Pyrrolidines; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Sulfonamides; Sulfonylurea Compounds

We describe the pharmacological characteristics of SM-19712 (4-chloro-N-[[(4-cyano-3-methyl-1-phenyl-1H-pyrazol-5-yl)amino]carbonyl] benzenesulfonamide, monosodium salt). SM-19712 inhibited endothelin converting enzyme (ECE) solubilized from rat lung microsomes with an IC50 value of 42 nM and, at 10 - 100 microM, had no effect on other metalloproteases such as neutral endopeptidase 24.11 and angiotensin converting enzyme, showing a high specificity for ECE. In cultured porcine aortic endothelial cells, SM-19712 at 1 - 100 microM concentration-dependently inhibited the endogenous conversion of big endothelin-1 (ET-1) to ET-1 with an IC50 value of 31 microM. In anesthetized rats, either intravenous (1-30 mg/kg) or oral (10-30 mg/kg) administration of SM-19712 dose-dependently suppressed the pressor responses induced by big ET-1. In acute myocardial infarction of rabbits subjected to coronary occlusion and reperfusion, SM-19712 reduced the infarct size, the increase in serum concentration of ET-1 and the serum activity of creatinine phosphokinase. The present study demonstrates that SM-19712 is a structurally novel, nonpeptide, potent and selective inhibitor of ECE, and SM-19712 is a valuable new tool for elucidating the pathophysiological role of ECE.

Topics: Acute Disease; Animals; Aspartic Acid Endopeptidases; Disease Models, Animal; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Glycopeptides; Lung; Male; Metalloendopeptidases; Myocardial Infarction; Pressoreceptors; Rabbits; Rats; Rats, Sprague-Dawley; Substrate Specificity; Sulfonamides; Sulfonylurea Compounds; Swine

Effects of SM-19712 (4-chloro-N-[[(4-cyano-3-methyl- 1-1-phenyl- 1H-pyrazol-5-yl)amino]carbonyl] benzenesulfonamide, monosodium salt), a novel endothelin converting enzyme (ECE) inhibitor, on ischemic acute renal failure (ARF) in rats were examined in comparison with those of phosphoramidon, a conventional ECE inhibitor. ARF was induced by occlusion of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after contralateral nephrectomy. Renal function in ARF rats markedly decreased at 24 h after reperfusion. Intravenous bolus injection of SM-19712 (3, 10, 30 mg/kg) prior to the occlusion attenuated dose-dependently the ischemia/reperfusion-induced renal dysfunction. Histopathological examination of the kidney of ARF rats revealed severe renal damages such as tubular necrosis, proteinaceous casts in tubuli and medullary congestion, all of which were dose-dependently attenuated by SM-19712. Protective effects of phosphoramidon (10 mg/kg) on ARF-induced functional and tissue damages were less potent than that of the same dose of SM-19712. Endothelin-1 (ET-1) content in the kidney after the ischemia/reperfusion was significantly increased, being the maximum level at 6 h after reperfusion, and this elevation was completely suppressed by the higher dose of SM-19712. Our findings support the view that renal ET-1 plays an important role in the development of ischemia/reperfusion-induced renal injury. SM-19712 may be useful in the treatment of ischemic ARF.

Topics: Acute Kidney Injury; Animals; Aspartic Acid Endopeptidases; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Glycopeptides; Ischemia; Kidney Function Tests; Male; Metalloendopeptidases; Protective Agents; Rats; Rats, Sprague-Dawley; Sulfonamides; Sulfonylurea Compounds