| Coronary atherosclerotic heart disease is a kind of disease which is caused by blood vessel stenosis or occlusion cavity due to coronary atherosclerosis or (and) by myocardial ischemia, hypoxia or necrosis due to coronary artery functional changes (cramps). Angina are a group of clinical syndromes which are caused by temporary myocardial ischemia, hypoxia and whose main performance is paroxysmal chest pain. In the modern society, alongside the changes of the influencing factors such as lifestyle, cardiovascular and cerebrovascular diseases have ranked among the major diseases that threaten people's life, health and quality of life. Moreover, the disease is becoming more and more harmful because of the gradually increasing incidence, especially the cardiovascular disease in China with the highest incidence rate among all diseases. Angina pectoris is one of the diseases. Along with the improvement of people's standard of living and the development of the aging of the population in China, its incidence and mortality rates are showing an upward trend year after year, and it has become the number one killer that endangers the life and health of our people. Although drug treatments keep emerging, results of the prevention of coronary heart disease are still far from satisfactory. Nowadays the pharmaceutical market is in urgent need of new drugs for the treatment of coronary heart disease with high efficiency and low toxicity.Panax quinquefolium(Linn.) belongs to Araliaceae and is a well-known medicinal plant. It is originally planted in North American. For many decades, researchers from all over the world have done a lot of research on P. quinquefolium.Rg3 is a monomer of traditional Chinese medicine which is extracted from P. quinquefolium, and it has been proved to have protective effect on cardiovascular.Pseudo-Ginsenoside GQ is a cyclization compound of Ginsenoside Rg3, and its chemical structure is similar with Rg3, but its pharmacological activity has not been known. In this experiment, we researched its protective effect on cardiovascular though the acute myocardial infarct model of ligated left anterior descending coronary artery, so as to exploit it as a new drug. In this experiment, the text was practiced by using the acute myocardial infarct(AMI) model of ligated left anterior descending coronary artery(LAD). We observed the variety of ST segment and T wave in ECG before and after ligation. MIS was calculated and activities of serum creatine phospho kinase(CPK), lactic dehydrogenase(LDH), aspartate aminotransferase(AST) and superoxide dismutase(SOD), content of malondialdehyde(MDA), prostaglandin I2 synthase(PGI2) and thromboxane A2 (TXA2) content of blood serum were determined. Blood was collected to determine low specific viscosity, platelet aggeration rate and platelet adherence rate. The protective effect of PGQ on experimental myocardial infarction in rats and its mechanism analysis were reported in this paper.ECG is the most essential, earliest using method to diagnose coronary heart disease. In this experiment, we observed T wave and ST segment from ECG dynamically. The result showed that PGQ could markedly inhibit the change of T wave and ST segment in ECG. It indicated that PGQ had the counteractive effect to myocardial ischemia infarction.Acute myocardial infarct(AMI) model was established as follows: after anesthetised with ether, rats were face upward fixed on the operating table. The chest was opened between the left third and fourth rib and the heart was exposed. Find the left anterior descending coronary artery and a nylon suture attached to a fine needle was placed under the left anterior descending coronary artery and ligated coronary artery immediately. After the heart was return into the chest, the blood and water in the chest were squeezed out and close the chest swiftly. The time opening the chest is no more than 30 seconds. Sham surgical group placed the suture only but not ligate coronary artery. Every group of rats was administrated(ip) 3d before operation. After 24 hours of ligating coronary artery, rats were anesthetized by 10% chloral hydrate (30mg/kg, ip) and then observed T wave and ST segment in ECG. The hearts were taken out and perfused with NS through aorta. Cut off atrium tissue and fat, crosscut myocardium of left ventricle into four or five slices,immerse them into the N-BT phosphate buffer in water bath at 37℃. Take them out after dying completely. Normal tissues were dyed while ischemic tissues not. Slice ischemic myocardium and weigh. MIS was expressed as the ratio of ischemic myocardium weight to left ventricle wet weight. Activities of serum CPK, LDH, AST and SOD, content of MDA, PGI2 and TXA2 of blood serum were determined. Blood was collected to determine low shearing specific viscosity, middle shearing specific viscosity, high shearing specific viscosity, and platelet aggregation rate and platelet adherence rate.The results showed that: In rats treated by PGQ, the change of T wave and ST segment in ECG and MIS was significantly reduced, the activities of serum CPK, AST and LDH declined. In addition, the content of serum MDA, TXA2 and viscosity of blood, platelet aggregation rate and platelet adherence rate were declined, activities of SOD and the content of PGI2 were increased markedly. What we observed suggest that PGQ has a protective effect on myocardial ischemia by improving free radicals and myocardial metabolism etc.At present, it is considered that the mechanism of preventing from myocardial ischemia is to decrease the oxygen-consumption of myocardium, to increase blood-supply of myocardial ischemia, to improve myocardial metabolism, to prevent myocardial cell from damage of peroxidation and to decrease the blood viscosity of myocardial ischemia etc. PGQ has displayed good pharmacological activities about several aspects as stated before which hits that PGQ prevents ischemial myocardia through many paths. In our views, PGQ may be an effective drug for prevention and cure of myocardial ischemia.
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