鞘内远端吗啡预处理对大鼠心脏缺血-再灌注损伤的保护作用

Protective effects of intrathecally remote morphine preconditioning against myocardial ischemiareperfusion injury in rats

目的探讨鞘内远端吗啡预处理减轻在体大鼠心肌缺血-再灌注损伤的作用机制。方法鞘内置管成功的雄性SD大鼠60只，随机（随机数字法）分为10组：缺血-一再灌注组（I／R组）、鞘内远端吗啡预处理组（RMPC组）、CGRPⅫ组、8-SPT组、HOE-140组、HEX组CGRP8-37＋RMPC组、8-SPT＋RMPC组、HOE-140＋RMPC组和HEX＋RMPC组。各组均采用缺血30min再灌注120min的方法制备心肌缺血／再灌注模型。RMPC组：在缺血前30min内经5min鞘内输注吗啡1μ/kg（用生理盐水稀释到l0μL），停止5min，共3个循环；I／R组给予等容量生理盐水。CGRP8-37组、8-SPT组、HOE-140组、HEX组分别在缺血前40min静脉注射CGRP8-37，8-SPT，HOE-140和HEX，CGRP8-377＋RMPC组、8-SPT＋RMPC组、HOE-140＋RMPC组和HEX＋RMPC组在注射吗啡前10min分别静脉注射上述阻断剂，上述阻断剂的剂量分别为3nmol／kg，7．5mg,／kg，300μ/kg，20mg／kg，均用生理盐水稀释到0．3mL。记录吗啡预处理前（基础值）、缺血前即刻、缺血30min、再灌注120min时MAP，HR以及MAP与HR的乘积（RPP）。基础值和再灌注120min时分别采集静脉血样，测定血清乳酸脱氢酶（LDH）活性，实验结束处死大鼠，取心肌组织，计算梗死区体积及梗死区面积与缺血危险区体积的比值（IS／AAR）。结果与I／R组比较，RMPC组IS体积、IS／AAR和再灌注120min时血清LDH活性降低（P〈0．05或P〈0．01）；与RMPC组比较，CGRP8-37＋RMPC组、8-SPT＋RMPC组、HOE-140＋RMPC组和HEX＋RMPC组Is体积、IS／AAR和再灌注120min时血清LDH活性升高（P〈0．05或P〈0．01）。结论鞘内远端吗啡预处理减轻在体大鼠心脏缺血后损伤，与CGRP、腺苷以及缓激肽的体液机制和神经机制共同参与介导有关。

Objective To investigate the mechanism of the protective effects induced by intrathecally remote morphine preconditioning （RMPC） against myocardial ischemia-reperfusion （I/R） injury in rats. Method Male SD rats weighing 280 - 320 g were used in this study. A needle was inserted through a surgically created hole into the spinal cord space. Sixty male SD rats, in which intrathecal needle was successfully placed without complication, were randomly （random number） divided into 10 groups of 6 animals each. In group I myocardial I/R was produced （I/R）. In group Ⅱ morphine was given intrathecally in 3 repeated doses of 1 μg/kg at 5 min intervals before ischemia （RMPC）. Antagonists CGRP8-37 （ CGRP receptor antagonist）, 8-SPT （adenosine receptor antagonist）, HOE-140 （bradykinin B2 receptor antagonist） and HEX （ autonomic nerve antagonist） were given intrathecally in group Ⅲ, IV, V and Ⅵrespeetively at 10 rain before RMPC. In group VII, VIU, IX and X CGRP8-37, 8-SPT, HOE-140 and HEX were given intrathecally respectively at 40 rain before ischemia. Myocardial I/R was produced by occlusion of left anterior descending branch （LAD） of coronary artery for 30 rain followed by 120 rain reperfusion. At the baseline and the end of 120 min reperfusion venous blood samples were taken for determination of LDH activity. The animals werethen killed and hearts removed for measurement of area at risk （AAR） and infarct size area （IS）. IS/AAR was calculated. Results The size of infarct area was smaller and IS/AAR ratio lower and significantly less LDH was released at the time of 120 min reperfusion in RMPC group （group Ⅱ ） than in group I/R （ group I ）. The protective effects of RMPC was abolished by intravenously pretreatment with CGRP8-37, 8-SPT, HOE-140 and HEX. Conclusions CGRP, adenosine, bradykinin and autonomic nerve are involved in the protective effects of intrathecally remote morphine preconditioning against myocardial I/R injury.