烟碱对大鼠心肌缺血再灌注损伤的影响

目的 探讨烟碱对大鼠心肌缺血再灌注损伤的影响.方法 健康成年雄性SD大鼠74只,体重200～250 g,随机分为5组:假手术组(S组,n=10)、缺血再灌注组(IR组,n=16)、烟碱400 μg/kg组(N1组,n=16)、烟碱40 μg/kg组(N2组,n=16)和α-银环蛇毒素组(α-BGT组,n=16).S组只穿线,不结扎左冠状动脉前降支;余各组采用结扎左冠状动脉前降支30 min,再灌注60 min的方法 制备大鼠心肌缺血再灌注模型.缺血前30 min时,N1组和N2组经右颈静脉分别注射烟碱400和40 μg/kg,α-BGT组右颈静脉注射N型胆碱能受体α-7亚单位特异性阻断剂α-银环蛇毒素1.0 μg/kg+烟碱400 μg/kg,S组和IR组右颈静脉注射等量生理盐水.再灌注60 min时,IR组、N1组、N2组和α-BGT组各取6只大鼠,测定左心室面积(LVA)、缺血危险区面积(AAR)和梗死区面积(IA),计算AAR/LVA和IA/LVA.再灌注60 min时,各组取10只大鼠,采集右颈动脉血样,测定血浆肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)的浓度和肌酸激酶同工酶(CK-MB)、乳酸脱氢酶(LDH)的活性;然后处死动物,取心肌组织,观察心肌超微结构,测定心肌髓过氧化物酶(MPO)活性.结果 与S组比较,IR组、N1组、N2组、α-BGT组血浆 TNF-α、IL-1β的浓度和CK-MB、LDH的活性升高,心肌MFO活性升高(P<0.05);与IR组比较,N1组IA/LVA、血浆TNF-α、IL-1β的浓度和CK-MB、LDH的活性、心肌MPO活性降低(P<0.05),心肌细胞超微结构损伤减轻,N2组和α-BGT组上述指标差异无统计学意义(P>0.05);与N1组比较,N2组和α-BGT组IA/LVA、血浆TNF-α、IL-1β的浓度和CK-MB、LDH的活性、心肌MPO活性升高(P<0.05),心肌细胞超微结构损伤加重.结论 烟碱可减轻大鼠心肌缺血再灌注损伤,其机制可能与激活胆碱能抗炎通路,抑制炎性反应有关.

Effects of nicotine on myocardial ischemia-reperfusion injury in rats

Objective To investigate the effects of nicotine on myocardial iscbemia-reperfusion (IR) injury in rats. Methods Seventy-four male SD rats weighing 200-250 g were randomly divided into 5 groups: group Ⅰ sham operation (group S, n=10), group Ⅱ IR (n = 16), group Ⅲ nicotine 400 μg/kg (group N1,n = 16), group Ⅳ nicotine 40 μg/kg (group N2, n = 16) and group Ⅴ nicotine 400 μg/kg + a-bungarotoxin(group a-BGT, n = 16). Myocardial ischemia was induced by occlusion of left anterior descending branch (LAD) of coronary artery for 30 min followed by 60 min of reperfusiou. LAD was exposed, but not occluded in group S. Nicotine 400 and 40 μg/kg were injected iv via the right jugular vein in group N1 and N2 respectively, and a-bungarotoxin 1.0 μg/kg and nicotion 400 μg/kg were injected iv via the fight jugular vein in group a-BGT at 30 min before myocardial ischemia. Equal volume of normal saline was injected instead in group S and IR. Six animals in each group were killed at 60 min of reperfusion and the hearts removed to measure the left ventricular area (LVA), area at risk (MR) and infarct area (IA) in group IR, N1,N2 and α-BGT. AAP/LVA and IA/LVA were calculated. The blood samples from right carotid artery were obtained for determination of plasma concentrations of TNF-α and IL-1β and activities of CK-MB and LDH. The animals were then killed and the hearts removed to observe the myocardial ultrastrueture and determine the activity of MPO. Results Compared with group S, plasma concentrations of TNF-α and IL-1β and activities of CK-MB and LDH, and myocardial MPO activity were significantly increased in group IR, N1, N2 and a-BGT (P<0.05). Compared with group IB, IA/LVA,plasma concentrations of TNF-α and IL-1β and activities of CK-MB and LDH, and myocardial MPO activity were significantly decreased in group N1 (P < 0.05), but there was no significant difference in the indices mentioned above between group N2 and IB and between group α-BGT and IB (P > 0.05). Compared with group N1,IA/LVA, plasma concentrations of TNF-α and IL-1βand activities of CK-MB and LDH, and myocardial MPO activity were significantly increased in group N2 and α-BGT (P < 0.05). The injury to myocardial uhrastructure was attenuated in group N1 as compared with group IR, while aggravated in group N2 and α-BGT as compared with group N1. Conclusion Nicotine can ameliorate the myocardial IR in rats. The mechanism may be related to the activation of the cholinergic anti-inflanunatory pathway and inhibition of the inflammatory response.