Aspartate and glutamate prevents isoproterenol-induced cardiac toxicity by alleviating oxidative stress in rats
Introduction
Despite the rapid advances that have been made in the treatment of coronary artery disease, myocardial infarction (MI) remains the major cause of death in the developed world and a major pathology issue worldwide (Adams, 2002). MI is characterized by necrosis of cardiac muscle induced by decreased supply of blood to a portion of the myocardium. A disparity between oxygen demand and supply leads to ischemic necrosis of heart muscle (DeBono and Boon, 1992). Free radicals are the key mediators associated with ischemia-reperfusion injury (Wattanapitayakul and Bauer, 2001). They may be formed by infiltration of white cells into ischemic myocardium or in the endothelial cell by the action of xanthine oxidase during the period of ischemia (McCord and Roy, 1982).
MI induced by isoproterenol (ISO), a synthetic catecholamine and β-adrenergic agonist, has been reported to show metabolic and morphological changes in the heart of experimental animals similar to those seen in human myocardial ischemia (Wexler, 1978). ISO, upon oxidation increases lipid peroxidation through enhanced free radical formation and causes severe stress in the myocardium resulting in infarct like necrosis of the heart muscles (Chattopadhyay et al., 2003; Rajadurai and Stanely Mainzen Prince, 2007). Experimental induction of myocardial infarction by isoproterenol in animal is a well established model to study the protective role of various cardio-protective agents.
Amino acids play a central role in myocardial energy metabolism, in coordination of mitochondrial and cytosolic biochemical processes (Barrio et al., 1982). It is well documented that exogenous amino acids are converted to intermediates of citrate cycle and by their subsequent anaerobic substrate-level phosphorylation protect ischemic myocardium (Sanborn et al., 1979; Lazar et al., 1980). Among the amino acids, aspartate and glutamate have frequently been considered to be anti-ischemic and shown to protect the heart from functional damages caused by global ischemia and reperfusion (Williams et al., 2001; Pisarenko et al., 2006). Exogenous glutamate and aspartate were reported to provide metabolic support for the ischemic heart (Pisarenko et al., 1995a; Pisarenko et al., 2006). The metabolic pathway is thought to be the aspartate–malate shuttle followed by citrate cycle which increased the production of succinate promoting ATP generation and protect ischemic myocardium (Oldroyd et al., 1990; Pisarenko et al., 1995a). It was speculated that glutamate could offer protection during oxidative stress through the formation of GSH from exogenous glutamate. Moreover, many of the citrate cycle intermediates has been shown to possess antioxidant properties in different in vitro and in vivo systems (Puntel et al., 2007).
A preliminary study reports the effect of aspartate and glutamate on myocardial infarction (Singh et al., 1989). However, to our knowledge no studies on the protective effect of these two amino acids during oxidative stress in MI had been performed. Hence this study was carried out to determine whether aspartate and glutamate could protect the myocardium against oxidative stress in MI induced rats. In the present work, we investigated the effect of aspartate and glutamate on cardiac marker enzymes, lipid peroxidation, glutathione, antioxidant enzymes and mitochondrial ATP in MI induced rats.
Section snippets
Chemicals
All fine chemicals including isoproterenol hydrochloride, sodium-l-aspartate, sodium-l-glutamate and epinephrine were purchased from Sigma (St. Louis, MO, USA). All other reagents and solvents used in this study were of the highest analytical grade, unless otherwise indicated.
Experimental design
Nearly 40 male albino rats of Wistar strain weighing approximately 150–200 g (4–5 months old) were obtained from the Laboratory Animal Maintenance Unit, Tamilnadu Animal Science and Veterinary University, Madavaram, India.
Results
Table 1 shows the effect of aspartate and glutamate on the activities of cardiac marker enzymes in serum of control and experimental rats. The activities of marker enzymes such as ALT, AST, LDH and CPK increased significantly (P<0.05) in the serum of MI induced rats as compared to control rats. The level of TBARS increased whereas the level of GSH decreased significantly (P<0.05) in the heart of MI induced rats when compared with control rats (Fig. 1). Table 2 depicts the activities of
Discussion
Heart can use different substrates for oxidation and normally the specific choice is largely determined by their availability. Glucose is the dominant fuel for heart but it can utilize free fatty acids and lactate as an energy source during fasting and exercise, respectively. During ischemia, anaerobic glycolysis can proceed as long as pyruvate and lactate are disposed of by cell. This process does not occur during severe ischemia and glycolysis ceases (Amark et al., 2006). In this context,
Acknowledgement
R. Sivakumar is grateful to acknowledge the financial assistance awarded by Council of Scientific and Industrial Research (CSIR), New Delhi, India.
References (49)
- et al.
Myocardial metabolism is better preserved after blood cardioplegia in infants
Ann Thorac Surg
(2006) - et al.
Protective effect of n-3 polyunsaturated fatty acids concentrate on isoproterenol-induced myocardial infarction in rats
Prostaglandins Leukot Essent Fatty acids
(2007) - et al.
Purification and characterization of the flavoenzyme glutathione reductase from rat liver
J Biol Chem
(1975) - et al.
Xanthine oxidase as a source of free radical damage in myocardial ischemia
J Mol Cell Cardiol
(1985) Tissue sulfhydryl groups
Arch Biochem Biophys
(1959)- et al.
Assays for differentiation of glutathione S-transferases
Methods Enzymol
(1981) - et al.
Cardiac transport of glutathione disulfide and S-conjugate. Studies with isolated perfused rat heart during hydroperoxide metabolism
J Biol Chem
(1984) - et al.
Antioxidant enzyme systems in rat liver and skeletal muscle. Influences of selenium deficiency, chronic training, and acute exercise
Arch Biochem Biophys
(1988) - et al.
Protein measurement with the Folin phenol reagent
J Biol Chem
(1951) - et al.
The role of superoxide anion in the autoxidation of epinephrine and a simple assay for superoxide dismutase
J Biol Chem
(1972)
Studies of hypoxemic/reoxygenation injury: without aortic clamping. VIII. Counteraction of oxidant damage by exogenous glutamate and aspartate
J Thorac Cardiovasc Surg
Fumarate-enriched blood cardioplegia results in complete functional recovery of immature myocardium
Ann Thorac Surg
Differing protection with aspartate and glutamate cardioplegia in the isolated rat heart
Ann Thorac Surg
Substrate accessibility to cytosolic aspartate aminotransferase improves posthypoxic recovery of isolated rat heart
Biochem Mol Med
Effect of mangiferin on mitochondrial energy production in experimentally induced myocardial infarcted rats
Vascul Pharmacol
Antioxidant properties of Krebs cycle intermediates against malonate pro-oxidant activity in vitro: a comparative study using the colorimetric method and HPLC analysis to determine malondialdehyde in rat brain homogenates
Life Sci
Preventive effect of naringin on cardiac markers, electrocardiographic patterns and lysosomal hydrolases in normal and isoproterenol-induced myocardial infarction in Wistar rats
Toxicology
Preventive effect of naringin on lipid peroxides and antioxidants in isoproterenol-induced cardiotoxicity in Wistar rats: biochemical and histopathological evidences
Toxicology
Effect of garlic (Allium sativum) on lipid peroxidation in experimental myocardial infarction in rats
J Ethnopharmacol
Colorimetric assay of catalase
Anal Biochem
Protective effect of aspartate and glutamate on cardiac mitochondrial function during myocardial infarction in experimental rats
Chem Biol Interact
Induction of lipid peroxidation in soybean mitochondria and protection by respiratory substrates
J Plant Physiol
Oxidative pathways in cardiovascular disease: roles, mechanisms, and therapeutic implications
Pharmacol Ther
Myocardial infarction in young vs old male rats: pathophysiologic changes
Am Heart J
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- 1
Present address: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
- 2
Present address: Department of Human Nutrition, Foods and Exercise, College of Agriculture and Food Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.