【作者】 许耀强；

【导师】 陈道中； 陈良万；

【作者基本信息】 福建医科大学 ， 胸心外科， 2002， 硕士

【摘要】 目的：冬眠心肌是指静息时心肌灌注量持续减少而导致左室功能受损的一种状态。冬眠心肌存在于多种临床缺血性心脏病中，但目前关于冬眠心肌的保护和治疗的研究不多。冬眠心肌治疗的根本手段是心肌血运重建术，寻求冬眠心肌有效的保护措施和方法，有重要的意义。L-精氨酸作为内源性一氧化氮(NO)的供体，对完全缺血心肌的保护作用已得到证实，但是对冬眠心肌的作用尚未得到研究。本实验通过外源性加入L-精氨酸(L-Arg)进行预处理，观察其对冬眠心肌的保护作用，同时比较L-精氨酸对停跳与不停跳两种状态下冬眠心肌的不同作用效果，并探讨其机制。 方法：36只健康雄性Sprague-Dawley大鼠，采用Langendorff离体心脏灌注装置，建立急性冬眠心肌模型。平衡灌注30分钟末，随机分为6组，每组6只。CON组：正常流量(3ml／g．min)灌注90分钟；HBN组：低流量(0.5ml／g．min)灌注90分钟；HR组：低流量灌注90分钟，恢复正常流量灌注30分钟；HAR组：低流量灌注90分钟，恢复正常流量灌注30分钟，低流量灌注期间灌注液中含有预处理药物L-Arg(1mmol/L)；HAIR组：低流量灌注90分钟，停搏液停跳60分钟，恢复正常流量灌注30分钟，低流量灌注期间灌注液中含有预处理药物L-Arg(1mmol/L)；HIR组：低流量灌注90分钟，停搏液停跳60分钟，恢复正常流量灌注30分钟。观察HR、HAR、HAIR、HIR各组在冬眠期间及恢复正常流量后心功能(HR、LVSP、LVDP、LVEDP、±dp/dt)恢复率的变化，测定各组冠状静脉流出液中心肌酶(CK、CK-MB)的漏出量、乳酸(Lac)产量、自由基(MDA)和自由基清除剂(SOD)含量、内皮功能(NO、ET)、心肌含水量(MWC)、心肌组织腺苷酸(ATP、ADP、AMP、TAN)含量和超微结构的变化。 结果：通过本实验的方法，首先在各组成功地建立了大鼠离体急性冬眠心肌模型：各组在低流量灌注期间，心功能较基础值明显降低；ATP含量下降，HBN组的ATP含量约下降到CON组的50％，HR、HAR、HAIR、HIR组的ATP含量也不同程度地降低；恢复正常流量后，心功能及心肌腺苷酸含量均有不同程度的恢复，L精氨酸顶处理对停跳与不停跳下大鼠急性冬眠心肌的保护作用3超微结构观察未见。0肌组织有不可逆性损害。。乙肌冬眠期间，MR组、！um组。O脏收缩功能恢复率（LVSP、士 dP／dt、和 LVDP）即显示优于m组与 HIR组（HO．05）。恢复流量后，HAR、HAIR组的心功能恢复率仍明显优于m与＊R组（P＜0．05），同时，Mm与mR组相比，其恢复程度较小（尸＜0．0引。冬眠期间，皿、mR组的比、CK－MB漏出即比 HAIR、HAR组明显增多（P＜0．05）。恢复流量后，HR、HAR组的。C肌酶漏出量较 HAIR和＊R组的少（P＜0．001），HAIR和 HIR组则无明显差别。冬眠 60分钟时，HR、HIR组的mA含量即较 HAR和 eIR组 的升高（P＜0．05），而恢复流量后，HAIR和 HIR组的mA升高较HAR和 HR组明显（P＜0．05），HAIR。HAR组SOD含量则明显高于HR、HIR组。冬眠期间 HAR和 HAIR组的n分泌较HR。mR组的少（尸＜0．0引，而皿水平明显高于m、mR组。恢复流量后，mm和HIR组的盯含量明显高于MR和 HR组，但＊R、HAIR两组的 NO比 HR、HIR两组的要高（尸＜0．01）。冬眠早期各组的乳酸产量均显著升高，但HR、mR组比HA R、MIR两组升高的更多（尸＜o．05）。MR组和邢工R组的心肌组织含水量低于册和HIR组（尸＜0．0引，MR组和Mm组则无明显差别。心肌组织的超微结构显示m、HAR组未见有不可逆性损害，且HR、HAR两组的损害较HAIR、HIR组的为轻。 结论：L－精氨酸对大鼠急性冬眠心肌具有确切的保护作用，且对不停跳状态下的冬眠心肌的保护作用更佳。可能与其增加内源性NO的合成而发挥其多种生物学效应的机制有关。更多还原

【Abstract】 Objective The term hibernating myocardium was described as a special state of impaired myocardial and left ventricular function at rest due to reduced coronary blood flow. Hiberniting myocardium has been demonstrated to accur in many kinds of clinical syndromes. But there is few studies on protection and treatment of hibernating myocardium at present. A donor of endorgenous nitric oxide桳-Arginine has been confirmed having protective effects on ischemic myocardium. Whether it can provide protective effects on hibernating myocardium has not known yet, in this study, we are intented to examine whether L-Arginine has beneficial effects on hibernating myocardium in two different states of beating or cardioplegia arrest and to explore its mechanisms.Methods The isolated rat hearts were perfused on a Langendorff perfusion device .36 Sprague-Dawley rat hearts were randomly divided into six groups when balanced perfusion finished. Controlled group (CON n=6)received persistently normal-flow perfusion for 90 minutes; Hibernating group(HBN n=6)received persistently low-flow perfusion for 90 minutes;Hibernating梤eperfusion group(HR n=6) received persistent low-flow perfusion for 90 minutes and subsequent normal-flow perfusion for 30 minutes; L-Arginine preconditioning and beating heart group(HAR n=6) received low-flow perfusion with KHB containing L-Arginine (Immol/L) for 90 minutes and subsequent normal-flow perfusion without L-Arginine for SOminutes; L-Arginine preconditioning and cardioplegia arrest group(HAIR n=6)received low-flow perfusion with KHB containing L-Arginine(Immol/L) for 90 minutes, then cardioplegia arrest for 60 minutes and subsequent normal-flow perfusion without L-Arginine for 30minutes; hibernating and Cardioplegia arrest group(HIR n=6)received low-flow perfusion for 90 minutes, then cardioplegia arrest for 60 minutes and subsequent normal-flow perfusion for 30 minutes ;The effects of L-Arginine on hibernating myocardium were assesed by measurement of hemodynamic parameters expressed as a percentage of baseline value, Myocardial enzemys leakout, Lactate release, MDA and SOD content, Endothelial function(NO and ET content), Myocardial water content, Myocardial nucleotides content (ATP, ADP, AMP, TAN) and ultrastructural alterations during hibernating or reperfusion.Results First of all, In the way which we designed, We successfully set up the model of short-term hibernating myocardium in isolated perfused rat hearts. During low-flow perfusion, heart contractile function in either group was injuried and identically lower than baseline ones. ATP content decreased by 50% in HBN group compared with CON group, and ATP content also reduced respectively in HR, HAR, HAIR and HIR groups. During hibernation, heart contractile function(LVSP , 眃p/dt , LVDP) in HAR, HAIR groups was much better than in HR and HIR(P < 0. 05). The recovery value of contractile function in HAR, HAIR groups was much more than in HR and HIR groups (P < 0. 05) during reperfusion. Myocardial enzemys leakout, lactate release, MDA and ET contents were more in HR and HIR groups than in HAR, HAIR groups(P < 0.05)during hibernation .while they were fewer in HR and HAR groups than in HAIR and HIR groups(P <0. 001)during perfusion. The production of NO kept more in HAR, HAIR groups than in HR and HIR groups persistently. The water cotent in HAR , HAIR groups is higher than in HR and HIR groups. Cardiomyocytes were not found irreversible ultrastructural alterations in HR and HAR groups,But ultrastructural alterations indicated that injury of myocytes in HAIR and HIR groups were more severe than in other groups.Conclusions L-Arginine preconditioning provides exactllyprotective effects on short-term hibernating myocardium, and especially on those in state of beating, The probable mechanism is L-Arginine induces increased generation of endogenous NO and takes its multibiological effects.更多还原