Molecular Mechanism of the Inhibitory Effect of Trilinolein on Endothelin-1-Induced Hypertrophy of Cultured Neonatal Rat Cardiomyocytes

Abstract

Trilinolein, isolated from the traditional Chinese herb Sanchi (Panax notoginseng), has been shown to have myocardial protective effects via its antioxidant ability. However, the cellular and molecular mechanisms of the protective effect of trilinolein in the heart remain to be elucidated. Oxidative mechanisms have been implicated in neonatal cardiomyocyte hypertrophy. We therefore have examined whether trilinolein attenuates reactive oxygen species (ROS) production and thus ET-1-induced hypertrophy of cardiomyocytes. Cultured neonatal rat cardiomyocytes were stimulated with ET-1 (10 nM), [³ H]leucine incorporation and the β-myosin heavy chain (β-MyHC) promoter activity were examined. Trilinolein (1 and 10 μM) inhibited the ET-1-induced increase of [³ H]-leucine incorporation in a concentration-dependent manner. Trilinolein (1 and 10 μM) also inhibited ET-1-induced β-MyHC promoter activity in cardiomyocytes. We further examined the effects of trilinolein on ET-1-induced intracellular ROS generation by measuring a redox-sensitive fluorescent dye, 2′,7′-dichlorofluorescin diacetate, fluorescence intensity. Trilinolein (1 and 10 μM) inhibited ET-1-increased intracellular ROS levels in a concentration-dependent manner. This increase of ROS by ET-1 (10 nM) or H₂O₂ (25 μM) was significantly inhibited by trilinolein (10 μM) and N-acetylcysteine (10 mM). Moreover, ET-1- or H₂O₂-induced β-MyHC promoter activity and protein synthesis were also inhibited by trilinolein (10 μM). These data indicate that trilinolein inhibits ET-1-induced β-MyHC promoter activity, and subsequent hypertrophy via its antioxidant ability in cardiomyocytes.

Trilinolein - endothelin-1 - cardiomyocyte hypertrophy - reactive oxygen species

References

• 1 Levy D, Anderson K M, Savage D D, Balkus S A, Kannel W B, Castelli W P. Risk of ventricular arrhythmias in left ventricular hypertrophy: the Framingham Heart Study.  Am J Cardiol. 1987;  60 560-5
• 2 Morgan H E, Baker K M. Cardiac hypertrophy. Mechanical, neural, and endocrine dependence.  Circulation. 1991;  83 13-25
• 3 Yamazaki T, Komuro I, Kudoh S, Zou Y, Shiojima I, Hiroi Y, Mizuno T, Maemura K, Kurihara H, Aikawa R, Takano H, Yazaki Y. Endothelin-1 is involved in mechanical stress-induced cardiomyocyte hypertrophy.  J Biol Chem. 1996;  271 3221-8
• 4 Force T, Haq S, Kilter H, Michael A. Apoptosis signal-regulating kinase/nuclear factor-kappaB: a novel signaling pathway regulates cardiomyocyte hypertrophy.  Circulation. 2002;  105 402-4
• 5 Choukroun G, Hajjar R, Kyriakis J M, Bonventre J V, Rosenzweig A, Force T. Role of the stress-activated protein kinases in endothelin-induced cardiomyocyte hypertrophy.  J Clin Invest. 1998;  102 1311-20
• 6 van Wamel A J, Ruwhof C, van der Valk-Kokshoom L E, Schrier P I, van der Laarse A. The role of angiotensin II, endothelin-1 and transforming growth factor-beta as autocrine/paracrine mediators of stretch-induced cardiomyocyte hypertrophy.  Mol Cell Biochem. 2001;  218 113-24
• 7 Yue T L, Gu J L, Wang C, Reith A D, Lee J C, Mirabile R C, Kreutz R, Wang Y, Maleeff B, Parsons A A, Ohlstein E H. Extracellular signal-regulated kinase plays an essential role in hypertrophic agonists, endothelin-1 and phenylephrine-induced cardiomyocyte hypertrophy.  J Biol Chem. 2000;  275 37 895-901
• 8 Komuro I, Yazaki Y. Control of cardiac gene expression by mechanical stress.  Annu Rev Physiol. 1993;  55 55-75
• 9 Cheng T H, Shih N L, Chen S Y, Wang D L, Chen J J. Reactive oxygen species modulate endothelin-I-induced c-fos gene expression in cardiomyocytes.  Cardiovasc Res. 1999;  41 654-62
• 10 Hirotani S, Otsu K, Nishida K, Higuchi Y, Morita T, Nakayama H, Yamaguchi O, Mano T, Matsumura Y, Ueno H, Tada M, Hori M. Involvement of nuclear factor-kappaB and apoptosis signal-regulating kinase 1 in G-protein-coupled receptor agonist-induced cardiomyocyte hypertrophy.  Circulation. 2002;  105 509-15
• 11 Higuchi Y, Otsu K, Nishida K, Hirotani S, Nakayama H, Yamaguchi O, Matsumura Y, Ueno H, Tada M, Hori M. Involvement of reactive oxygen species-mediated NF-kappa B activation in TNF-alpha-induced cardiomyocyte hypertrophy.  J Mol Cell Cardiol. 2002;  34 233-40
• 12 Luo J D, Xie F, Zhang W W, Ma X D, Guan J X, Chen X. Simvastatin inhibits noradrenaline-induced hypertrophy of cultured neonatal rat cardiomyocytes.  Br J Pharmacol. 2001;  132 159-64
• 13 Shih N L, Cheng T H, Loh S H, Cheng P Y, Wang D L, Chen Y S, Liu S H, Liew C C, Chen J J. Reactive oxygen species modulate angiotensin II-induced beta-myosin heavy chain gene expression via Ras/Raf/extracellular signal-regulated kinase pathway in neonatal rat cardiomyocytes.  Biochem Biophys Res Commun. 2001;  283 143-8
• 14 Hong C Y, Lai L J, Shiao M S, Chiang B N. Effect of triacylglycerols on erythrocyte deformability in vitro .  Prostaglandins Leukot Essent Fatty Acids. 1993;  48 351-3
• 15 Chan P, Thomas G N, Tomlinson B. Protective effects of trilinolein extracted from Panax notoginseng against cardiovascular disease.  Acta Pharmacol Sin. 2002;  23 1157-62
• 16 Chan P, Niu C S, Cheng J T, Tsao C W, Tsai S K, Hong C Y. Trilinolein preserves mitochondria ultrastructure in isolated rat heart subjected to global ischemia through antioxidant activity as measured by chemiluminescence.  Pharmacology. 1996;  52 216-25
• 17 Chan P, Niu C S, Tomlinson B, Hong C T, Chen J P, Hong C Y, Tsai S K, Cheng J T. Effect of trilinolein on superoxide dismutase activity and left ventricular pressure in isolated rat hearts subjected to hypoxia and normoxic perfusion.  Pharmacology. 1997;  55 252-8
• 18 Wang D L, Chen J J, Shin N L, Kao Y C, Hsu K H, Huang W Y, Liew C C. Endothelin stimulates cardiac alpha- and beta- myosin heavy chain gene expression.  Biochem Biophys Res Commun. 1992;  183 1260-5
• 19 Schluter K D, Piper H M. Regulation of growth in the adult cardiomyocytes.  FASEB J. 1999;  13 17-22
• 20 Ito H. Endothelins and cardiac hypertrophy.  Life Sci. 1997;  61 585-93
• 21 Chan P, Cheng J T, Tsao C W, Niu C S, Hong C Y. The in vitro antioxidant activity of trilinolein and other lipid-related natural substances as measured by enhanced chemiluminescence.  Life Sci. 1996;  59 2067-73