The effect of mebudipine on cardiac function and activity of the myocardial nitric oxide system in ischaemia-reperfusion injury in rats

Anti-arrhythmogenic and anti-inflammatory effects of troxerutin in ischemia/reperfusion injury of diabetic myocardium

INTRODUCTION

Medicinal plants are increasingly used in the treatment of cardiovascular diseases due to their multifaceted properties. This study was designed to investigate anti-arrhythmic and anti-inflammatory potentials of the natural bioflavonoid, troxerutin (TXR) in myocardial ischemia/reperfusion (I/R) injury in diabetic rats.

METHODS

Male Wistar rats were randomly divided into 4 groups (control, control + TXR [150 mg/kg, daily], diabetic, and diabetic + TXR). Type-1 diabetes was induced by an intraperitoneal injection of streptozotocin (50 mg/kg) and lasted for 10 weeks. After mounting on the Langendorff apparatus, isolated hearts in all groups received a normal Krebs-Henseleit solution for 20 min of stabilization period, followed by 30 min of regional ischemia through ligation of the left anterior descending coronary artery, and 60 min of full reperfusion. During the experiment, the electrocardiograms were recorded and the arrhythmias [number, duration and incidence of premature ventricular complexes (PVC), ventricular tachycardia (VT), ventricular fibrillation (VF), and arrhythmia score] during I/R phases were assessed based on the Lambeth Convention. Ischemic left ventricular samples were used to determine the activities of lactate dehydrogenase (LDH), interleukin-1beta (IL-1β), and tumor necrosis factor (TNF-α).

RESULTS

The arrhythmias induced by I/R were not significantly changed in diabetic group as compared to the control group. However, pretreatment with TXR significantly reduced the number of PVC and duration and incidence of VF in ischemic phase in comparison to the untreated animals (P < 0.05). In addition, the duration, and incidence of most arrhythmias during reperfusion phase were significantly declined by TXR administration in both control and diabetic groups (P < 0.05). Pretreatment of rats with TXR significantly reduced myocardial inflammatory cytokines TNF-α and IL-1β levels after I/R insult in diabetic as well as control hearts (P < 0.05).

CONCLUSION

Preconditioning with TXR could provide cardioprotection by anti-arrhythmic and anti-inflammatory effects against I/R injury in rat hearts. This effect of TXR can introduce this material as a protective agent in cardiovascular diseases.

Influence of Two Various Durations of Resistance Exercise on Oxidative Stress in the Male Rat's Hearts

INTRODUCTION

The previous studies have suggested that alteration in oxidative stress and antioxidant defense depends on various factors, such as mode, intensity, frequency and duration of exercise. In this study, we compared the effects of two various durations of resistance exercise (1 month and 4 month) on oxidative stress and antioxidant status in cardiac tissue.

METHODS

Thirty Wistar male rats divided into 3 groups: control (sedentary), exercise-1 (regular exercise for 1 month) and exercise-2 group (regular exercise for 4 months). After the final to the experiment, the rats were anesthetized, and then blood and heart samples were obtained and used to determine glutathione peroxidase (GPX), superoxide dismutase (SOD), malondialdehyde (MDA) and biochemical estimation.

RESULTS

MDA levels between control and exercise-2 groups showed no significant difference, hence, MDA level in exercise-1 group was higher compared to control group (P < .01). The heart GPX activity increased significantly in exercise-2 group regarding other groups (P < .01). The SOD activities of groups were similar. Creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations increased in the exercise-1 compared to the other groups (P < .01).

CONCLUSION

Our results indicate that in heart, the adaptation and alteration in oxidative stress and cell injury level depend on duration of exercise.

Contribution of apoptosis in myocardial reperfusion injury and loss of cardioprotection in diabetes mellitus

Ischemic heart disease is one of the major causes of death worldwide. Ischemia is a condition in which blood flow of the myocardium declines, leading to cardiomyocyte death. However, reperfusion of ischemic regions decreases the rate of mortality, but it can also cause later complications. In a clinical setting, ischemic heart disease is always coincident with other co-morbidities such as diabetes. The risk of heart disease increases 2-3 times in diabetic patients. Apoptosis is considered to be one of the main pathophysiological mechanisms of myocardial ischemia-reperfusion injury. Diabetes can disrupt the anti-apoptotic intracellular signaling cascades involved in myocardial protection. Therefore, targeting these changes may be an effective cardioprotective approach in the diabetic myocardium against ischemia-reperfusion injury. In this article, we review the interaction of diabetes with the pathophysiology of myocardial ischemia-reperfusion injury, focusing on the contribution of apoptosis in this context, and then discuss the alterations of pro-apoptotic or anti-apoptotic pathways probably responsible for the loss of cardioprotection in diabetes.

Determination of Mebudipine in Human Plasma by Liquid Chromatography-tandem Mass Spectrometry

In previous studies, mebudipine, a dihydropyridine calcium channel blocker, showed a considerable potential to be used in cardiovascular diseases. The aim of the current study was to develop a valid method using reversed-phase high performance liquid chromatography coupled with electrospray ionization mass spectrometry to assay mebudipine in the human plasma. Separation was achieved on a Zorbax Eclipse(®) C18 analytical column using a mobile phase consisted of methanol/water (90:10, v/v). The flow rate was 0.6 mL/min and carbamazepine was used as an internal standard (IS). This method involved the use of [M +Na](+) ions of mebudipine and IS at m/z 411 and 259, respectively with the selected ion monitoring (SIM) mode. There were no interfering peaks from endogenous components in blank plasma chromatograms. Standard curves were linear (r(2)>0.99) between 5 to 100 ng/mL. The mean extraction efficiency was about 84% and the limit of quantification for mebudipine was 5 ng/mL in plasma. The coefficient of variation and error at all of the intra-day and inter-day assessments were less than 11%. The results indicated that this method is a fast, accurate, sensitive, selective and reliable method for the determination of mebudipine in the human plasma. The assay method has been successfully used to estimate plasma concentration of mebudipine after the oral administration of 2.5 mg tablet in healthy adults.

Effect of mebudipine on oxidative stress and lipid peroxidation in myocardial ischemic-reperfusion injury in male rat

BACKGROUND

Myocardial infarction (MI) is the acute condition of necrosis in myocardium which occurs as a result of imbalance between coronary blood supply and myocardial demand. The resultant oxidative stress excess leads to worsen the condition. The aim of this study was to investigate the effect of mebudipine, a new dihydropyridine calcium channel blocker, on lipid peroxidation and antioxidant enzymes in myocardial ischemia-reperfusion injury.

MATERIALS AND METHODS

Male Wistar rats (250-300 g) were randomly divided to Control-ischemic, mebudipine-ischemic and vehicle (ethanol-ischemic) groups. The hearts of anaesthetized rats were removed and mounted on Langendorff apparatus and perfused by Krebs-Henseleit solution under constant pressure of 75 mmHg at 37°C. Ischemic groups were received 30 min global ischemia and 120 min reperfusion and the mebudipine and vehicle groups received mebudipine (0.1 nM) or ethanol (0.01%)-enriched solution 25 min before global ischemia. Malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase levels of heart tissue samples were determined by commercial specific Kits.

RESULTS

Mebudipine significantly reduced the MDA level (2.3 ± 0.07 nmol/mg protein) as the biochemical indicator of oxidative damage and lipid peroxidation product as compared with those of vehicle (4.6 ± 0.01 nmol/mg protein) and control groups (4.8 ± 0.09 nmol/mg protein). Furthermore, antioxidant enzymes SOD (0.1 ± 0.006 in drug vs. 0.037 ± 0.009 U/mg Protein in control), GPX (16 ± 0.009 in drug vs. 0.068 ± 0.01 U/mg Protein in control) and catalase activities (0.075 ± 0.006 in drug vs. 0.028 ± 0.002 U/mg Protein in control), activities of myocardium were significantly increased by mebudipine (P < 0.01).

CONCLUSION

Our results showed that mebudipine may have antioxidant activity against myocardial ischemia-reperfusion injury since it decreased oxidative stress by enhancing the enzymatic antioxidant defense and inhibiting the lipid peroxidation. Thus, this drug can reduce the intensity of cardiac ischemic insults.