【摘要】 目的研究呼气末二氧化碳分压（PetCO₂）与异丙酚静脉麻醉下老龄大鼠容量反应的相关性。方法筛选出20只健康的22月龄SD大鼠,随机将其分为对照组和观察组各10只。采用靶控输注异丙酚和瑞芬太尼对观察组大鼠进行麻醉维持,术中采用调节通气量使PetCO₂降低到35、 30及25 mmHg,采取通过口明视气管插管构建大鼠吸入麻醉模型。对照组不给予任何麻醉药物,放置到麻醉箱中吸入氧气2 h,氧流量为2 L/min;对两组大鼠的容量反应性的变化及容量负荷进行比较。根据Morris水迷宫对两组大鼠进行认知功能的检测。完成水迷宫行为学检测后,随机处死4只大鼠采取高尔基染色方进行海马树突棘密度的检测,剩余6只大鼠处死后采取酶联免疫吸附试验（ELISA）对海马内丙二醛（MDA）和超氧化物歧化酶（SOD）的含量进行测定。采用海马组织+RT-PCR法对海马N-甲基D-天冬氨酸受体（NMDAR）、酶联免疫吸附试验（NRI）和（NR2B）mRNA的表达进行测定。结果在对照组中,被动抬腿试验（PLR）能够导致中心静脉压（CVP）明显升高（P<0.05）,心率（HR）、收缩压（SBP）、舒张压（DBP）、心排血指数（CI）无明显变化（P>0.05）,但观察组PLR能够导致CVP、SBP、DBP及CI明显变化（P<0.05）,而对HR无明显变化（P>0.05）。两组PLR试验均可以提升每搏输出量（SV）,而观察组SV明显高于对照组（P<0.05）,观察组大鼠镇静后容量有反应性亚型比例增加幅度明显高于对照组（P<0.05）。与对照组比较,观察组大鼠游泳路程和逃避潜伏期明显延长,穿越平台次数和平台所在象限停留时间明显缩短（P<0.05）,对照组海马内MDA含量明显升高,SOD含量和树突棘密度明显下降（P<0.05）,与对照组比较,观察组NMDAR mRNA表达明显上调（P<0.05）,NRI和NR2B mRNA表达差异无统计学意义（P>0.05）。结论将PetCO₂与异丙酚静脉麻醉应用于大鼠的麻醉和镇静,能够增加容量反应性,而对心肌收缩力不存在影响或影响较小,但会导致老龄大鼠术后认知功能障碍,其作用机制可能与提升氧化应激反应及降低其海马内树突棘密度有关。更多还原

【Abstract】 Objective To study the correlation between end tidal carbon dioxide partial pressure and volume response in elderly rats under intravenous anesthesia with propofol.Methods 20 healthy 22-month-old SD rats were randomly divided into control group(n=10) and observation group(n=10). Target-controlled infusion of propofol and remifentanil was used to maintain anesthesia in anesthetized rats. PetCO2 was reduced to 35, 30 and 25 mmHg by adjusting ventilation volume during operation. The inhalation anesthesia model was established in aged rats by intubation with open-mouth tracheal intubation. Rats in the control group were given no anesthetics and placed in the anesthesia box to inhale oxygen for 2 hours. The oxygen flow rate was 2 L/min. The volume responsiveness and capacity load of two groups of rats were compared. The Morris water maze was used to detect the cognitive function of two groups of rats. Four rats were sacrificed randomly to detect the dendritic spine density of hippocampus by Golgi staining. The remaining six rats were sacrificed to determine the contents of malondialdehyde(MDA) and superoxide dismutase(SOD) in hippocampus by ELISA. RT-PCR was used to detect the NMDAR, NRI and NR2 B mRNA expressions in hippocampus.Results In the control group, there was significant effect of PLR on CVP(P<0.05), there were no significant effects of PLR on HR, SBP, DBP, CI(P>0.05), but in the observation group, there were significant effects of PLR on CVP, SBP, DBP and CI(P<0.05), while there were no significant effect on HR(P>0.05). The PLR test in both groups could increase SV, while SV in the observation group was significantly higher than that of control group(P<0.05). The proportion of reactive subtypes increased by 50.00% in the observation group after sedation(P<0.05). Compared with the control group, the swimming distance and escape latency of the observation group were significantly prolonged, the number of crossing platforms and the quadrant residence time of platforms were significantly shortened(P<0.05), the content of MDA in the hippocampus of the control group was significantly increased, the content of SOD and the density of dendritic spine were significantly decreased(P< 0.05). The expression was significantly up-regulated(P<0.05), and there was no significant difference in NRI and NR2 B mRNA expression(P>0.05). Conclusions The application of end-expiratory carbon dioxide partial pressure and propofol intravenous anesthesia to the anesthesia and sedation of aged rats can increase the volume responsiveness, but has no or little effect on the myocardial contractility. However, it can lead to cognitive dysfunction in aged rats after operation. The mechanism may be related to the promotion of oxidative stress response and the reduction of oxidative stress response. There was a certain relationship between the density of dendritic spines in the hippocampus.更多还原