慢性心力衰竭大鼠脑血流量变化及其一氧化氮合酶作用机制

Study on Cerebral Blood Flow in Rats with Chronic Heart Failure and Mechanism of NOS

目的探讨慢性心力衰竭后大鼠脑血流量的变化及其一氧化氮合酶作用机制。方法采用结扎左冠状动脉前降支造成心肌梗死后慢性心力衰竭模型,60 d后采用超声心动检测心功能;通过Morris水迷宫定向航行实验和穿台实验评价认知功能;使用激光散斑多普勒血流仪检测脑血流量;通过免疫印迹法检测大鼠脑皮质内皮型一氧化氮合酶(eNOS)与诱导型一氧化氮合酶(iNOS)的含量。结果与假手术组相比,模型组射血分数(EF)和短轴缩短率(FS)明显降低(P<0.05),心功能下降;与假手术组相比,模型组定向航行实验的潜伏期与总路程差异均无统计学意义(P>0.05),穿台实验中穿台次数明显下降(P<0.01);与假手术组相比,模型组脑血流量差异无统计学意义(P>0.05);模型组大鼠大脑皮质eNOS表达量与假手术组相比有降低趋势,但eNOS/iNOS比值明显下降(P<0.05)。结论慢性心力衰竭大鼠存在明显的认知功能障碍,主要表现为记忆力下降。尽管慢性心力衰竭大鼠与血管舒张和收缩相关的一氧化氮合酶系统已出现异常,但是其脑部血流量并无明显变化。

Objective To explore the changes and mechanisms of cerebral blood flow in rats after chronic heart failure.Methods The model of chronic heart failure after myocardial infarction was established by ligating anterior descending branch of the left coronary artery.The echocardiography was used to detect cardiac function after surgery for 60 days.The cognitive function was evaluated by acquisition trial and probe trial of Morris water maze.Cerebral blood flow was measured by laser speckle Doppler flowmeter.The contents of eNOS and iNOS in the cerebral cortex were detected by western blotting.Results Compared with the sham group,EF and FS values in the model group significantly decreased(P<0.05)and cardiac function was decreased.There was no significant difference between the sham group and model group in the average latency and path length of acquisition trial(P>0.05),however,the number of crossing the platform significantly reduced(P<0.01).Cerebral blood flow did not change in heart failure rats compared with that in the sham group(P>0.05).The eNOS expression of the model group was lower than that in the sham group,and eNOS/iNOS ratio decreased significantly(P<0.05).Conclusion The rats with chronic heart failure had obvious cognitive dysfunction,which was mainly manifested as the decline of the memory.Although the NOS system associated with vasodilation and contraction was impaired,however the cerebral blood flow of chronic heart failure rats did not change.