动物造模 z-bo 2022-02-03 442

　　[Modeling mechanism] By ligating the coronary arteries of the model animal, the coronary arteries become narrowed or occluded, and the myocardium supplied from the coronary arteries is ischemia or necrosis, thereby causing myocardial infarction in the model animal.

　　[Modeling method] In short, the general coronary artery ligation is mainly divided into three steps. After the animal is first anesthetized, a left thoracotomy is performed in the fourth intercostal space, and then the pericardium is carefully opened. If the ligation is successful, the left anterior descending coronary artery (LAD) is ligated. An electrocardiogram (ECG) showed a typical ST-segment elevation, the anterior wall of the left ventricle also turned white, and finally the chest cavity was closed. If you need to create a model of myocardial ischemia-reperfusion injury, you can remove the ligature 30 minutes after ligating the LAD to cause ischemia-reperfusion injury. In the specific modeling method, take the following animals as examples.

　　Boar: Choose a piglet weighing 18-22 kg, first apply 30-5 g/L pentobarbital to the ear of the pig by intravenous injection of 3-5 ml, and let it stand for 3-5 minutes. The pig lies in an unstable position. Next, use a trocar to quickly establish a vein leading to the ear vein of the pig. Before placing the animal on its back on the operating table in the operating room, perform anesthesia with 30 g/L pentobarbital (1 ml/kg) slowly Bolus. Put it in place. Separate and expose the trachea, and intubate it. Connect the ventilator. Open the chest along the fourth intercostal space of the sternum to expose the heart, lift the pericardium, and cut vertically to form the pericardial bed. Unscrew a silk thread to ligate the middle and lower 1/3 joints of the LAD trunk. Four multi-point fixed epicardial electrode linings were sewn on the surface of the heart, and a multi-channel physiological recorder was used to record the epicardial electrogram before and after ligation, and ST segment elevation was used as a successful model to close the chest cavity and pull it out Ventilator.

　　Inu: usually used beagle dogs, weighing 10-18 kg, anesthetize the animal intravenously with 3% sodium pentobarbital 30 mg/kg, and fix it on the operating table on the right. The trachea is intubated and connected to the ventilator. Open the chest along the 4th or 5th intercostal space along the left edge of the sternum to expose the heart, cut the pus, and form the pericardial bed. Separate the middle and lower 1/3 of the LAD trunk, and thread a silk thread under it for ligation. The multi-point fixed epicardial electrode lining was sutured to the surface of the heart, and a multi-channel physiological recorder was used to record the epicardial electrogram before and after ligation, and ST segment elevation was used as a successful model. .. Close the chest cavity, pull out the ventilator, and handle the animal as needed.

　　Rat: For intraperitoneal injection, select adult Wistar rats weighing about 250 g and 10 ml/kg sodium pentobarbital 10/ml, and inject 20-30 μg/kg atropine intraperitoneally before intubation. First intubate the trachea and connect the ventilator. Fix the limbs of the rat in a supine position and pull out the hair. The upper boundary is at the level of the upper sternum, and the lower boundary is at the level of the lower sternum. After sterilization, make a longitudinal incision of 1.5 to 2.0 cm in length along the left end of the sternum, centered on the strongest point of the apex, and open the chest one layer at a time in the chest cavity. Cut the open heart capsule to expose the left atrial appendage, and then insert the needle 2-3 mm below the left atrial appendage. The midpoint of the ligation is the junction of the left atrial appendage and the pulmonary artery cone. The ligation direction is parallel to the end of the left atrial appendage and perpendicular to the atrioventricular junction. The depth of acupuncture is 1.5 to 2.0mm. The coronary arteries of rats are thin and it is difficult to separate the myocardium. To prevent damage to the myocardium and blood vessels, sutures can be used to ligate the myocardium of appropriate strength. Threads are often used. Return the heart to the chest cavity and quickly suture the chest wall. Stop artificial respiration. The signs of successful modeling are the heart wall bleaching and the ECG monitoring ST segment elevation.

　　Mouse: Use 25-30g mouse. Pentobarbital sodium (50 mg/kg) was injected intraperitoneally. After anesthetizing the mouse, paste it on the control panel. Shave the breast, sterilize it with 70% ethanol, and then send a 22G trocar into the trachea under direct vision to reconstruct the airway. The breathing rate is set to 100-110 breaths/minute. Take the midline of the left sternum perpendicular to the ribs and cut the skin. In the exhalation phase of the mouse, the pectoralis major and pectoralis minor muscles were divided into several layers, and the third, fourth, and fifth ribs were cut out. Use a chest opener to support and fix the sternum to expose the heart and cut the heart capsule. Find the left anterior descending branch under the microscope, and ligate the left anterior descending branch to about 1 mm with 10.0 ophthalmic sutures at the lower end of the left atrium, with a span of about 1 mm. Observe the changes of the ECG ST-T and the color of the myocardium. Remove the chest opener and close the chest cavity with 8-0 non-invasive sutures. Suture the skin, maintain the ventilator for about 30 minutes after the operation, and pull out the mouse after waking up. [Model Features] Coronary artery ligation is the most commonly used method to replicate myocardial infarction models, and it is also a recognized model for studying myocardial ischemic injury. The scope of ligation methods used to create animal models of myocardial infarction is clearer and the effect is more precise. You can model different areas of the heart according to your research needs, and monitor and evaluate the model in real time through electrocardiogram, pathology, serum enzymology, etc. However, the ligation method requires thoracotomy on the animal, and involves surgical procedures such as tracheal intubation, anesthesia, and post-operative management. The process is very complicated, requires advanced surgical techniques and equipment, and is not suitable for general laboratory modeling research. The trauma is great and the impact on animals is great. In addition, the high postmortem mortality even further increases the cost of modeling. Some studies have shown that the mortality of animals after surgery may be as high as 60%. I will.

　　【Model evaluation and application】Most myocardial infarctions clinically are caused by coronary atherosclerosis. Thrombosis after bleeding from atherosclerotic vulnerable plaque is the pathological basis of coronary occlusion. 50% of human myocardial ischemia occurs in the left anterior descending blood supply area. Therefore, the animal model of acute myocardial ischemia caused by coronary artery ligation has a high degree of clinical similarity and can be used to study the changes in hemodynamics and myocardial metabolism after myocardial ischemia. Research on drugs used to prevent and treat myocardial ischemia. However, because myocardial infarction caused by ligation has no such pathological basis, thoracotomy will cause some physiological and biochemical changes in animals, which makes model animals and clinical myocardial infarction different. I will. However, precise modeling effects and precise control of ligation methods still have specific application space. This model is suitable for studies that require clinically similar changes in myocardial injury to clinically or require precise control of the time and degree of infarction. Because the modeling process is relatively complex, a laboratory with specific surgical instruments and technical infrastructure is required.