| BackgroundWith the widespread application of percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) in ischemic heart disease, myocardial ischemia/reperfusion (MI/R) injury has been receiving intensive attention from heart disease experts. In the past few years, besides applying western medicines and the gene treatment method, the cardioprotective effect of Chinese herb in MI/R has been one of the most intense research topics in biomedical research and clinical practice.At present, the mechanism of MI/R has considered including energy metabolism disorder, attenuation in Ca2+ overload, the generation of oxygen free radicals and neutrophil infiltration leading to inflammation. However, the substantial role of the mechanism of ischemia/reperfusion (I/R) injury remains unclear. However, recently, many studies find that inflammatory reaction plays an important part in MI/R injury. Traditional Chinese medicine can protect against MI/R injury by inhibiting the recruitment and infiltration of inflammatory cells, mediating the synthesis and secretion of cytokine and recovering the balance of the pro-inflammatory cytokine.Qidan Tongmai tablet (QDTMT), which has a cardioprotective effect against MI/R injury, is a Qi-reinforcing and blood-activating prescription. In our previous study, we have found that QDTMT has several mechanisms of protection . Firstly, it can help an ischemic heart to increase the intake and utilization of glucose in order to improve energy metabolism during MI/R. Secondly, it can eliminate or inhibit the injury of oxygen free radicals effectively. Thirdly, it can inhibit Ca2+ overload in the mitochondrion of cadiocytes. Additionally, it can also down-regulate the pro-inflammatory mediator, interleukin-6 (IL-6) and tumor necrosis factor-α(TNF-α). Therefore, the major objective of this study was to assess whether the cardioprotection of Qidan Tongmai tablet is also related to attenuation of the inflammatory reaction via up-regulation of IL-10 induced by ischemia/reperfusion. It was suggested to play a protective role against MI/R injury.Aim1,To determine whether Qidan Tongmai tablet reduces MI/R injury by improving the changes in electrocardiogram, reducing myocardial infarction size, improving the pathological changes of myocardium and the degree of injury in myocardial ultrastructure . 2,To investigate whether the anti-inflammatory cytokine, IL-10 plays a protective role as another independent mechanism involved in cardioprotection of Qidan Tongmai tablet.Methods1,Protocal: Male Sprague-Dawley rats (body weight, 225±25 g) were randomly divided into six groups: sham operation group, model group, diltiazem hydrochloride (5 mg/kg?d) group, QDTMT high dose (3.24 g/kg?d) group, QDTMT medium dose (1.08 g/kg?d) group and QDTMT low dose (0.36 g/kg?d) group. There were six rats in sham operation group and eleven rats in other five groups. Drugs were dissolved in distilled water to lavage the rats. Rats in sham operation group and model group were lavaged with distilled water instead. The rats were administrated corresponding drugs for seven days continuously. All rats were subjected to 30 minutes of ischemia and 2 hours of reperfusion.2,Myocardium ischemia/reperfusion injury model: Male SD rats were subjected to 30 minutes of ischemia and 2 hours of reperfusion. The rats were anaesthetized with sodium pentobarbital (45mg/kg, ip), tracheotomized, intubated and ventilated with room air by an animal respirator. Left thoracotomy at the fifth intercostal space and pericardiotomy were performed, a 5/0 braided silk suture was placed around the left anterior descending coronary artery, and the coronary artery was occluded by pulling on the suture. In all groups except sham operation group, the left anterior descending branch of the coronary artery was occluded for 30 minutes followed by 2 hours reperfusion (removal of the ligature).3,Estimate Index: Heart rate (HR) during I/R and arrhythmia in the first twenty minutes after reperfusion were observed by ECG. After reperfusion, infarct size (IS) and area at risk (AAR) were evaluated with the triphenyltetrazolium chloride (TTC) - Evans blue technique. A section of tissue was taken from the ischemic heart and observed by HE stain. The myocardial ultrastructural alterations of rats in every group were observed with transmission electron microscope. The whole blood was collected via right common carotid artery and the serum level of IL-10 was measured by enzyme linked immunosorbent assay (ELISA).Results1,Heart rate: Compared with model group, during MI/R, heart rate was slowed in QDTMT high dose group and diltiazem hydrochloride group (P < 0.05, P < 0.01). Heart rate of QDTMT medium dose group was decreased significantly in thirty minutes of ischemia (P < 0.05). Heart rate of QDTMT low dose group was slowed, however, insignificant difference was showed between it and model group (all P > 0.05).2,Arrhythmia: During the first twenty minutes after reperfusion,premature ventricular contractions (PVC), ventricular tachycardia (VT) and ventricular fibrillation (VF) were observed in the rats of the model group and its arrhythmia almost appeared at the first five minutes of reperfusion. The incidence of VT and VF in the model group was 87.5% and 62.5% respectively and the duration of VT and VF in this group was 31.67 seconds and 153.85 seconds respectively. Meanwhile, PVC, VT and VF were also occurred in QDTMT high dose group. However, compared with the model group, the appearance of VT and VF was delayed, their durations were obviously shortened (P < 0.05, P < 0.01). Their incidences were also reduced and the type of arrhythmia was almost PVC and VT. The duration of ventricular arrhythmia was shortened significantly (P < 0.01) and the incidence of ventricular arrhythmia was also reduced (P < 0.05) in diltiazem hydrochloride group. Compared with the model group, the score of arrhythmia was significantly decreased in this group (P < 0.01).3,Myocardial infarction size: In the rat hearts of model group, there appeared obvious myocardial infarction. With the administration of high dose of QDTMT and diltiazem hydrochloride, their myocardial infarction sizes were significantly reduced (P < 0.05, P < 0.01).4,Effects on pathological changes of myocardium via Hematoxylin-eosin (HE) stain: Normal myocardium fibers were in excellent alignment and identified clearly. In addition, the cells were observed with undamaged membrane and without any indication of necrosis and the infiltration of neutrophilic leukocyte. After MI/R, myocardiocytes became disturbed, some of them were turbid and swollen, cardiac fibers were unclear or vanished. QDTMT high dose group made these pathogenesis alterations less severe than model group.5,Myocardial ultrastructures: In the model group, there was apparent cellular and tissue swelling. Most myofibrils had either disappeared or been disorganized or disarrayed. Mitochondria were obviously swollen and loosely arranged. Mitochondrial membranes were vague or partly ruptured and cristae were obviously loose and dissolved, a lot of vacuoluses were formed. In the QDTMT high dose group and the diltiazem hydrochloride group, however, ultrastructural organization appeared basically close to normal except that cristae were basically congested with a little vacuolation. 6,The serum of IL-10 after MI/R: In comparison with the sham operation group, all rats subjected to MI/R injury were obviously increased (all P < 0.01). The serum level of IL-10 in three QDTMT groups and diltiazem hydrochloride group was higher than that in model group, however, the level in the QDTMT high dose group and the diltiazem hydrochloride group was the highest among other groups (P < 0.05, P < 0.01).Conclusion1,Administration of QDTMT could obviously protect the myocardium against I/R injury.2,QDTMT could facilitate the expression of endogenous IL-10 in MI/R rats, which was one of the mechanisms of QDTMT against I/R injury.These results could provide experimental evidences for researching and developing Chinese herbs which can protect against I/R injury.
|
PDF Full Text Request