Prevention by amiodarone of phospholipid depletion in isoproterenol-induced ischemia in rats

Trace Element Determination and Cardioprotection of Terminalia pallida Fruit Ethanolic Extract in Isoproterenol Induced Myocardial Infarcted Rats by ICP-MS

The trace elements and minerals in Terminalia pallida fruit ethanolic extract (TpFE) were determined by the instrument inductively coupled plasma-mass spectrometry (ICP-MS), and the cardioprotection of TpFE against isoproterenol (ISO)-administered rats was studied. Rats were pretreated with TpFE (100, 300, and 500 mg/kg bw) for 30 days, with concurrent administration of ISO (85 mg/kg bw) for two consecutive days. The levels of trace elements and minerals in TpFE were below the permitted limits of World Health Organization standards. ISO administration significantly increased the heart weight and cardiac marker enzymes in serum, xanthine oxidase, sodium, and calcium in the heart, whereas significantly decreased body weight, reduced glutathione, glutathione-S-transferase, superoxide dismutase, and potassium in the heart. Oral pretreatment of TpFE significantly prevented the ISO-induced alterations. This is the first report that revealed the determination of trace elements and mineral nutrients of TpFE by ICP-MS which plays a principal role in the herbal drug discovery for the treatment of cardiovascular diseases.

Edaravone protects rats against oxidative stress and apoptosis in experimentally induced myocardial infarction: Biochemical and ultrastructural evidence

OBJECTIVES

The present study was designed to evaluate the cardioprotective potential of edaravone on oxidative stress, anti-apoptotic, anti-inflammatory and ultrastructure findings in isoproterenol (ISO) induced myocardial infarction (MI) in rats.

METHODS

Rats were pretreated with edaravone (1, 3, 10 mg/kg body weight-1 day-1) intraperitoneally. MI was induced by subcutaneous administration of ISO (85 mg/kg body weight-1) at two doses with 24h interval.

RESULTS

ISO treated rats showed significant increase in the levels of thiobarbituric acid reactive substances (TBARS) and decreased levels of reduced glutathione, glutathione perdoxidase, glutathione reductase and glutathione-S- transferase in the cardiac tissues. Moreover, significant increase in the levels of lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), C--reactive protein and caspase-3 activity was observed in ISO treated group. Pretreatment of ISO intoxicated rats with edaravone showed significant decrease in the level of TBARS, increased activities of antioxidant enzymes and significantly decreased levels of LDH and CK-MB. Moreover, results also showed decreased C-reactive protein level, caspase-3 activity and maintained ultrastructure of the myocardial cells.

DISCUSSION

Our study suggests that edaravone possess strong cardioprotective potential. Edaravone may have exhibited cardioprotective effects by restoring antioxidant defense mechanism, maintaining integrity of myocardial cell membrane, reducing apoptosis and inflammation against ISO induced MI and associated oxidative stress.

Protective effect of neferine against isoproterenol-induced cardiac toxicity

The present study was designed to investigate the cardioprotective effect of neferine against isoproterenol-induced myocardial infarction. Neferine was given orally for 30 days, and isoproterenol was injected subcutaneously for 2 days. Histopathological examination of heart tissue of isoproterenol-treated rats showed myocardial necrosis. Biochemical analysis of isoproterenol-treated rats showed significant increase in the serum marker enzymes--creatine kinase, lactate dehydrogenase, and aspartate transaminase and increased serum glycoprotein components with a concomitant decrease in the heart tissue homogenate when compared to control. Increased lipid peroxidation and decreased antioxidants reduced glutathione, superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase and altered lipid profile in serum and tissue was also recorded in the isoproterenol-treated rats, whereas the rats which received neferine pre-treatment followed by isoproterenol injection showed minimal histological changes, absence of inflammation, and a significant decrease in the serum marker enzymes and serum glycoprotein components with a concomitant increase in the heart tissue homogenate when compared to isoproterenol group. Neferine pre-treatment restored the altered biochemical parameters and lipid profile to near normal. The results of the present study showed that neferine exerts strong antioxidant property against isoproterenol-induced oxidative stress and can be used as a potent cardioprotective agent against isoproterenol-induced myocardial infarction.

Specific antioxidant selenoproteins are induced in the heart during hypertrophy

Selenium (Se) is thought to confer cardioprotective effects through the actions of antioxidant selenoprotein enzymes that directly limit levels of ROS such as hydrogen peroxide (H(2)O(2)) or that reverse oxidative damage to lipids and proteins. To determine how the selenoproteome responds to myocardial hypertrophy, two mouse models were employed: triidothyronine (T3)- or isoproterenol (ISO)-treatment. After 7days of T3- and ISO-treatment, cardiac stress was demonstrated by increased H(2)O(2) and caspase-3 activity. Neither treatment produced significant increases in phospholipid peroxidation or TUNEL-positive cells, suggesting that antioxidant systems were protecting the cardiomyocytes from damage. Many selenoprotein mRNAs were induced by T3- and ISO-treatment, with levels of methionine sulfoxide reductase 1 (MsrB1, also called SelR) mRNA showing the largest increases. MsrB enzymatic activity was also elevated in both models of cardiac stress, while glutathione peroxidase (GPx) activity and thioredoxin reductase (Trxrd) activity were moderately and nonsignificantly increased, respectively. Western blot assays revealed a marked increase in MsrB1 and moderate increases in GPx3, GPx4, and Trxrd1, particularly in T3-treated hearts. Thus, the main response of the selenoproteome during hypertrophy does not involve increased GPx1, but increased GPx3 for reducing extracellular H(2)O(2) and increased GPx4, Trxrd1, and MsrB1 for minimizing intracellular oxidative damage.

Protective effect of L-arginine in experimentally induced myocardial ischemia: comparison with aspirin

OBJECTIVE

Coronary artery diseases including myocardial ischemia (MI) remain one of the leading causes of death worldwide. This study was designed to compare the protective effect of L-arginine versus aspirin from the biochemical changes associated with MI injury.

EXPERIMENTAL DESIGN

Four groups of male New Zealand white rabbits were investigated. Normal group (n = 8) rabbits were fed standard chow pellets, untreated MI group (n = 16), where hypercholesterolemia was induced by feeding the animals with a diet containing 2% cholesterol for 28 days, L-arginine group (n = 12) rabbits were fed a 2% cholesterol-enriched diet in conjunction with L-arginine (2.25 g %) in drinking water for 28 days, and aspirin group (n = 12) rabbits were fed 2% cholesterol-enriched diet in conjunction with aspirin administered orally (0.7 mg/kg per d) for 28 days. After 28 days, MI was induced in all groups, except the normal group, by a single subcutaneous (sc) injection of isoproterenol hydrochloride (0.2 mg/kg body weight [bw]). Animals were sacrificed 6 hours later.

RESULTS

Our results showed that L-arginine was more effective than aspirin in reducing platelet aggregation, reducing low-density lipoprotein (LDL) oxidizability, preventing aortic intimal thickening, and maintaining histological architecture of the myocardium. Both drugs, however, had similar positive effects on plasma fibrinogen levels and on the prevention of myocardial release of cardiac troponin I and creatine kinase-MB. The effect on hypercholesterolemia was insignificant for both drugs. Aspirin was more effective than L-arginine in prolonging prothrombin time.

CONCLUSION

L-arginine supplementation represents a potentially novel nutritional strategy for preventing and treating coronary artery diseases especially in cases of aspirin resistance and/or hypersensitivity.

Cardioprotective effect of oleanolic acid on isoproterenol-induced myocardial ischemia in rats

This study was designed to investigate the protective effect of oleanolic acid (OA) against isoproterenol-induced myocardial ischemia in rat myocardium. Wistar strain rats were pretreated with OA (20, 40, and 60 mg/kg, s.c) for 7 days and then intoxicated with isoproterenol (ISO, 85 mg/kg, sc for 2 consecutive days). Heart were excised from the experimental animals and assessed for the activities of marker enzymes [alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)], the levels of lipid peroxide products [thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HP) and conjugated dienes (CD)], myeloperoxidase (MPO), lipid profiles [total cholesterol (TC), free cholesterol, ester cholesterol, triglycerides (TG), free fatty acids (FFA) and phospholipids (PL)], and membrane-bound ATPase enzymes (total ATPase, Na(+)K(+) ATPase, Ca(2 +) ATPase, and Mg(2 +) ATPase). Troponin T and I were estimated in plasma. Leakage of cardiac markers, elevated lipid peroxidation with increased lipid profiles and decreased activities of membrane-bound ATPase enzymes were confirmed the severe myocardial damage occurring as a consequence of isoproterenol-induced ischemia, and they also showed the significant improvement effected by oleanolic acid pretreatment. These findings provided evidence that oleanolic acid was found to be protecting rat myocardium against ischemic insult and the protective effect could attribute to its anti-oxidative, anti-hyperlipedemic, and anti-arrhythmic properties as well as its membrane-stabilizing action.

Phenylalkylamine Ca2+ antagonist binding protein. Molecular cloning, tissue distribution, and heterologous expression

We recently characterized (Moebius, F. F., Burrows, G. G., Striessnig, J., and Glossmann H. (1993) Mol. Pharmacol. 43, 139-144) and purified (Moebius, F. F., Hanner, M., Knaus, H. G., Weber, F., Striessnig, J., and Glossmann, H. (1994) J. Biol. Chem. 269, 29314-29320) a binding protein for the phenylalkylamine Ca2+ antagonist emopamil. The emopamil-binding protein (EBP) acts as a high affinity acceptor for several antiischemic drugs and thus represents a potential common molecular target for antiischemic drug action. Degenerate oligonucleotides were synthesized according to the N-terminal amino acid sequence of purified EBP and used to amplify a guinea pig cDNA with reverse transcriptase-polymerase chain reaction and to clone full-length cDNAs from guinea pig and human liver cDNA libraries. The cDNAs coded for 229 (guinea pig) and 230 (human) amino acid 27-kDa polypeptides without significant sequence homology with any known protein. However, EBP shared structural features with pro- and eukaryotic drug transport proteins. The amino acid identity between human and guinea pig EBP was 73%. Hydrophobicity plots predicted four transmembrane segments. The C terminus contained a lysine-rich consensus sequence for the retrieval of type I integral membrane proteins to the endoplasmic reticulum. The heterologous expression of human and guinea pig EBP in Saccharomyces cerevisiae demonstrated that the expression of EBP alone is sufficient to form high affinity drug- and cation-binding domains identical to the [3H]-emopamil-binding site of guinea pig liver. Northern and Western blot analysis revealed high abundance of EBP in guinea pig epithelial tissues as liver, bowel, adrenal gland, testis, ovary, and uterus and low densities in brain, cerebellum, skeletal muscle, and heart. EBP is suggested to be the first structurally characterized member of a family of high affinity microsomal drug acceptor proteins carrying so called sigma-binding sites.

Respiration and mitochondrial ATPase in energized mitochondria during isoproterenol-induced cell injury of myocardium

1. Respiration of mitochondria, membrane potential and mitochondrial ATPase under energized conditions were studied in rat myocardium during cell injury induced by treatment with isoproterenol. 2. Increase in the state 4 rate of respiration and ADP:O ratio, as well as decrease in the state 3 rate and Respiratory Control Ratio (RCR) were found. 3. The optimum pH for RCR and for maximum ATPase activity was shifted to lower values. 4. The state 3 respiration was more sensitive to oligomycin inhibition. 5. The mitochondria showed lower ability to generate membrane potential. 6. An increase in the K0.5 values for catalytic sites II and III of mitochondrial ATPase at pH 7.4 and 5.5 was found. 7. These results are consistent with alterations on the integrity of mitochondrial membrane, and corroborate with the hypothesis of changes on the mitochondrial ATPase during isoproterenol-induced cell injury of myocardium.

In vivo phosphorus-31 spectroscopic imaging in patients with global myocardial disease

The goals of this study were to determine whether abnormalities in phosphorus metabolism could be noninvasively detected using phosphorus-31 nuclear magnetic resonance spectroscopy in patients with dilated cardiomyopathy and left ventricular hypertrophy, and whether these patient groups could be distinguished from each other based on parameters obtained using this technique. Seventeen patients and 14 control subjects were studied using nuclear magnetic resonance spectroscopy. Spectra were obtained from the human heart at rest using 3-dimensional spectroscopic imaging as a localization technique. Data were acquired over an average volume of 48 cc in 26.3 minutes using a 2 tesla imaging and spectroscopy unit. The ratio of phosphocreatine to adenosine triphosphate was 0.89 +/- 0.88 (mean +/- standard error) in normal subjects and did not differ significantly in patients with dilated cardiomyopathy or left ventricular hypertrophy. A prominent peak in the phosphodiester region was seen much more frequently in patients with dilated cardiomyopathy, resulting in significantly higher ratios of phosphodiester to phosphocreatine (1.28 +/- 0.35) and phosphodiester to adenosine triphosphate (0.79 +/- 0.18) in this group compared to normal subjects (0.33 +/- 0.08 and 0.29 +/- 0.08, respectively). However, the various patient groups could not be reliably distinguished from each other based on spectral patterns. These studies demonstrate the feasibility of performing phosphorus-31 nuclear magnetic resonance spectroscopic imaging in patients with myocardial disease. The initial results indicate that, under resting conditions, the ratio of phosphocreatine to adenosine triphosphate is not consistently altered in patients with severe global cardiomyopathies or hypertrophy. Phosphodiesters are elevated in some patients with dilated cardiomyopathy, a finding that may signify abnormal phospholipid metabolism in this condition.

Molecular pharmacological aspects of antiarrhythmic activity. I. Class I and class III compounds and lipid peroxidation

The effect of nineteen antiarrhythmic agents on nonenzymatic lipid peroxidation, using rat hepatic microsomes, was studied. Lipid peroxidation was induced by Fe2(+)-ascorbic acid and assayed spectrophotometrically by measuring the 2-thiobarbituric acid reactive material. The compounds tested have various structural characteristics and represent class I and III of antiarrhythmics as classified by Vaughan Williams. The RM values, derived from reversed-phase thin-layer chromatography, were determined, and sigma f values calculated in order to correlate lipophilicity and antioxidant activity. The antiarrhythmics studied inhibited lipid peroxidation to various degrees. No apparent structural factor could definitely be attributed to this effect and antioxidants are found among both class I and class III compounds. There is a trend toward a parabolic relationship between antioxidant potency and lipophilicity. Three of the tested antiarrhythmics, namely the lipophilic amiodarone, aprindine and asocainol, were very potent antioxidants, and a further investigation of concentration and time dependency of lipid peroxidation was performed. It is suggested that, at least for some antiarrhythmic drugs, antioxidant activity may be part of their mode of action, and that it may form an additional beneficial feature for the treatment of cardiac failure.

Kinetic properties of mitochondrial ATPase during isoproterenol-induced cardiomyopathy

1. The kinetic characteristics of the ATP hydrolysis by membrane-bound and Triton X-100 solubilized mitochondrial ATPase, during the isoproterenol-induced cardiomyopathy, were investigated. 2. An increase in the inhibitory action of the oligomycin, a decrease in the affinity of the ATP binding sites and an increase of both activation energy and rate of thermal inactivation were observed for mitochondrial ATPase. 3. The possibility that the changes described are related to the modifications of the active configuration of mitochondrial ATPase, during the isoproterenol-induced cardiomyopathy, is discussed.

Changes in the phospholipid content in the left heart ventricle of male mice during repeated administration of isoprenaline

1. Male mice were injected 5 mg/kg isoprenaline (IPRO) daily and the heart weight, dry weight and phospholipid content in the left ventricle determined 24 hr after the last injection on days 1, 3, 5 and 10. 2. The phospholipid content sinks during the experiment, but the onset of the change is different in different phospholipids: for diphosphatidylglycerol it is clearly significant after 3 days, for phosphatidylcholine and phosphatidylethanolamine after 5 days and for sphingomyelin after 10 days; the relative amplitude of the change in this latter phospholipid was greatest of all. 3. If IPRO is given for 3 days and physiological saline for next 7 days, the content of some phospholipids (PE, SM and PG) continued to decrease. This suggests an important delayed effect of IPRO action.