间歇性低压低氧处理降低大鼠右心室乳头肌对异丙肾上腺素的反应

发布时间：2018-04-01 00:01

本文选题：间歇性低压低氧　切入点：异丙肾上腺素　出处：《河北医科大学》2007年硕士论文

【摘要】： 目的:近年来,大量研究表明间歇性低压低氧(intermittent hypobaric hypoxia, IHH)处理具有明显的心脏保护作用,并越来越受到人们的重视和关注,已成为临床医学、高原医学和运动医学研究的热点之一。众多研究显示,IHH处理显著提高心肌抗缺血/再灌注、缺氧/复氧损伤的能力,表现为显著减轻缺血再灌注后心脏舒缩功能降低,缩小冠脉闭塞所致心肌梗死面积,以及抗缺血再灌注心律失常作用。目前已知IHH心脏保护作用主要涉及以下几方面,如IHH可以改善心肌物质与能量代谢的能力,增加氧的有效利用、减少ATP耗竭,增加心肌毛细血管密度、改善心肌供血,增强心肌抗氧化酶活性,增加心肌对氧自由基的抵抗力;开放KATP通道,尤其是线粒体上的KATP通道;减弱缺血/再灌注时肌浆网的损伤,维持Na+/Ca2+交换体(NCX)的活性,减少钙超载;抑制线粒体通透转换孔的开放;上调心肌iNOS的mRNA和蛋白的水平,导致NO的生成增多;抑制心肌细胞的凋亡等等。但有关IHH心脏保护作用的确切机制远未阐明。心脏β肾上腺素能受体在正常心脏活动调节中发挥重要作用,其功能下调或受体阻断可表现某种心脏保护作用。有报道IHH可减轻心肌缺血期钙超载程度,其机理可能与α1B肾上腺素能受体亚型有关。IHH对心脏β肾上腺素能受体影响如何,或心脏β肾上腺素能受体是否参与IHH心脏保护作用未见报道。本研究应用经典的细胞内微电极记录技术及肌肉收缩描记方法,观察β肾上腺素能受体激动剂-异丙肾上腺素(ISO)对IHH处理14天、28天和42天大鼠右心室乳头肌动作电位和机械收缩的影响,以探讨IHH对大鼠心肌β肾上腺素能受体的影响。方法:雄性Sprague-Dawley(SD)大鼠,以戊巴比妥钠(30-35mg/kg,i.p.)腹腔注射麻醉,仰位固定,开胸迅速取出心脏,置于冷冻(0-4℃)改良台氏液中以制备右室乳头肌标本。制备好的乳头肌腱膜端固定于张力换能器,另一端用不锈钢针固定于灌流槽的硅橡胶上。用改良台氏液(pH 7.4±0.05)以12ml/min的速度灌流标本,温度维持在37℃,并持续充以纯氧。标本在灌流液中平衡一小时后开始实验。以刺激频率为1HZ,波宽3ms,强度为2倍阈强度的矩形脉冲刺激标本,诱发乳头肌动作电位和收缩。用尖端电阻10-20兆欧的玻璃微电极缓慢插入乳头肌细胞内,记录细胞内动作电位。电活动经微电极放大器、高速数模转换器储存于计算机,通过我室自编的程序进行自动采集、分析。动作电位参数包括静息电位(RP)、动作电位(OS)、动作电位幅值(APA)、动作电位0相最大上升速率(V_(max))、复极化50%(APD_(50))和90%的时间(APD_(90))。机械收缩通过压力换能器储存于计算机,肌肉收缩参数包括最大收缩张力(P_(max))和最大张力上升速度(P_(dT/dt))。用累加给药法观察不同浓度异丙肾上腺素(ISO, 10~(-8) ,10~(-7),10~(-6)mol/L)对大鼠右心室乳头肌动作电位和机械收缩的影响。结果:(1)IHH明显延长大鼠右心室乳头肌动作电位时程:APD_(50)由对照组的23.2±5.5 ms分别延长为35.0±7.6 ms、31.7±6.0 ms、48.3±3.4 ms;APD90由对照组的72.5±9.8 ms分别延长为100.2±5.9 ms、99.2±9.0 ms、133.8±21.2 ms;(2)ISO浓度依赖性地增加各组动物右心室乳头肌动作电位幅值(APA)、动作电位超射(OS)、动作电位0期最大上升速率(V_(max)),延长动作电位复极化50%(APD_(50))、复极化90%(APD90)时间,并增加机械收缩的最大收缩张力(P_(max))和最大张力上升速度(P_(dT/dt));(3)与对照组相比较,IHH组ISO引起的乳头肌动作电位及机械收缩的反应明显降低。结论:IHH明显降低大鼠右心室乳头肌对ISO的反应,表明心脏β肾上腺素能受体功能下降,此作用可能是IHH心脏保护作用的机制之一。
[Abstract]:Objective: in recent years, a large number of studies show that intermittent hypobaric hypoxia (intermittent hypobaric, hypoxia, IHH) treatment has protective effect on the heart obviously, and people pay more and more attention and concern, has become one of the hot points of clinical medicine, plateau medicine and sports medicine. Many studies showed that IHH treatment significantly improved myocardial ischemia / reperfusion, hypoxia / reoxygenation injury, showed significantly reduced after ischemia reperfusion of cardiac systolic and diastolic function decreased, reducing the area of myocardial infarction caused by coronary artery occlusion, ischemia reperfusion and anti arrhythmia effect. The cardioprotective effects of known IHH mainly involves the following aspects, such as the ability of IHH can improve myocardial energy and matter the metabolism, increase the effective utilization of oxygen, reduce ATP depletion, increase myocardial capillary density, improve myocardial ischemia, enhance myocardial antioxidant enzyme activity, increased myocardial oxygen Radical resistance; open KATP channel, especially on the mitochondrial KATP channel; weaken the damage of sarcoplasmic reticulum during ischemia / reperfusion, maintain the Na+/Ca2+ exchange (NCX) activity, reduce calcium overload; inhibition of mitochondrial permeability transition pore opening; mRNA and upregulation of myocardial iNOS level increase the formation of NO; inhibition of myocardial apoptosis and so on. But the exact mechanism of the cardioprotective effects of IHH are far from clear. Cardiac beta adrenergic receptors play an important role in the regulation of normal cardiac activity, its function can be reduced or blocking the heart protective effect is a table. It has been reported that IHH can reduce the degree of myocardial ischemia during calcium overload 1B, its mechanism may be related to alpha adrenergic receptor subtype.IHH on cardiac beta adrenergic receptor to, or cardiac beta adrenergic receptors are involved in IHH cardiac protection
Protective effect has not been reported. This study used the classic intracellular microelectrode recording technique and muscle contraction were recorded, the observation of beta adrenergic receptor agonist isoproterenol (ISO) of IHH for 14 days, 28 days and 42 days of rat right ventricular papillary muscle action potential and mechanical contraction effect can influence on myocardial beta adrenergic receptor in rats to investigate the IHH.
Methods: male Sprague-Dawley rats (SD) with sodium pentobarbital (30-35mg/kg, i.p.) intraperitoneal injection of anesthesia, fixed on back and chest quickly remove the heart, placed in the freezer (0-4 DEG C) modified Tyrode's solution in preparation of right ventricular papillary muscle specimens. The nipple tendon membrane prepared end is fixed on the tension the transducer, the other end with a stainless steel needle is fixed in the perfusion chamber. The silicone rubber with modified Tyrode's solution (pH 7.4 + 0.05) at a speed of 12ml/min perfusion was maintained at a temperature of 37 DEG C, and continuously filled with pure oxygen. The specimen began to experiment in the perfusate after one hour. In order to balance the stimulus frequency 1HZ, 3MS wave width, intensity is 2 times the threshold intensity of rectangular pulse stimulation specimens, action potential of papillary muscle and contraction induced by glass microelectrode. The tip resistance of 10-20 megohms slowly inserted into the papillary muscle cell, intracellular recording action potentials. The electrical activity of the microelectrode amplifier, High Speed DAC storage Stored in the computer room, through my own program for automatic acquisition and analysis. The action potential parameters including resting potential (RP), action potential (OS), amplitude of action potential (APA), phase 0 of the action potential maximum rise rate (V_ (max) 50% (APD_), repolarization (50) and 90%) time (APD_ (90)). The mechanical contraction pressure transducer is stored in the computer, the muscle contraction parameters including maximum isometric tension (P_ (max)) and the maximum tension of rising velocity (P_ (dT/dt)). The effects of different concentrations of isoproterenol with the cumulative dosing method (ISO, 10~ (-8), 10~ (-7), 10~ (-6) mol/L) effect on rat right ventricular papillary muscle action potential and contraction.
Results: (1) IHH significantly prolonged rat right ventricular papillary muscle action potential duration: APD_ (50) by 23.2 in the control group were extended to 35 + 5.5 MS + 7.6 MS, 31.7 MS + 6, 48.3 + 3.4 MS; APD90 from a control group of 72.5 + 9.8 MS were extended to 100.2 + 5.9 MS, 99.2 + 9 ms 133.8 + 21.2 MS; (2) ISO concentration dependently increased in each animal right ventricular papillary muscle action potential amplitude (APA), action potential overshoot (OS), action potential 0 maximum rise rate (V_ (max)), prolonged action potential repolarization (APD_ 50% (50)), 90% (APD90) repolarization time and increase the maximum isometric tension mechanical contraction (P_ (max)) and the maximum tension of rising velocity (P_ (dT/dt)); (3) compared with the control group, the action potential of papillary muscle and mechanical contraction caused by ISO of the IHH group was significantly decreased.
Conclusion: IHH significantly decreases the response of the right ventricular papillary muscles to ISO, indicating that the function of cardiac beta adrenergic receptor is decreased, which may be one of the mechanisms of IHH cardioprotection.

【学位授予单位】：河北医科大学
【学位级别】：硕士
【学位授予年份】：2007
【分类号】：R363

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