目的观察不同浓度丙泊酚对机械性刺激作用脑区的影响,探讨丙泊酚的镇痛作用。方法将20名健康志愿者随机分为浅麻醉组和深麻醉组,采用功能性磁共振成像(fMRI)进行检测,fMRI扫描序列=结构像扫描+功能像扫描,其中功能像扫描=(20 s on+20 s off)×6次机械性刺激(P1)+靶控输注(TCI)不同浓度丙泊酚+重复机械性刺激(P2)。结果浅麻醉组(第2次刺激-第1次刺激,即P2-P1)fMRI下显示激活脑区为扣带回、丘脑、小脑,(第1次刺激-第2次刺激,即P1-P2)fMRI下显示激活颞叶、额叶、枕叶;深麻醉组(P2-P1)小脑明显激活,(P1-P2)可见扣带回和丘脑激活。TCI丙泊酚后,给予P2,(深麻醉组-浅麻醉组)可见小脑激活。结论不同浓度丙泊酚对脑区的激活不同,丙泊酚可能通过不同作用机制发挥镇痛作用。
Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippocampus which is involved in memory function has not been studied, we investigated the effects of etomidate on both delayed rectifier potassium current （IK（DR）） and transient outward potassium current （I_K（A）） in acutely dissociated rat hippocampal pyramidal neurons.Methods Single rat hippocampal pyramidal neurons from male Wistar rats of 7-10 days were acutely dissociated by enzymatic digestion and mechanical dispersion according to the methods of Kay and Wong with slight modification. Voltage-clamp recordings were performed in the whole-cell patch clamp configuration. Currents were recorded with a List EPC-10 amplifier and data were stored in a computer using Pulse 8.5. Student＇s paired two-tail t test was used for data analysis. Results At the concentration of 100 μmol/L, etomidate significantly inhibited IK（DR） by 49.2% at ＋40 mV when depolarized from -110 mV （P 〈0.01, n=8）, while did not affect IK（A） （/1=8, P 〉0.05）. The IC50value of etomidate for blocking IK（DR）was calculated as 5.4 μmol/L, with a Hill slope of 2.45. At the presence of 10 μmol/L etomidate, the V1/2 of activation curve was shifted from （17.3±1.5） mV to （10.7±9.9） mV （n=8, P 〈0.05）, the V1/2 of inactivation curve was shifted from （-18.3±2.2） mV to （-45.3±9.4） mV （n=8, P 〈0.05）. Etomidate 10 μmol/L shifted both the activation curve and inactivation curve of IK（DR））to negative potential, but mainly affected the inactivation kinetics.Conclusions Etomidate potently inhibited IK（DR） but not IK（A） in rat hippocampal pyramidal neurons. IK（DR） was inhibited by etomidate in a concentration-dependent manner, while IK（A） remained unaffected.
Objective To investigate the effect of propofol on brain regions at different sedation levels and the association between changes in brain region activity and loss of consciousness using blood oxygen level-dependent functional magnetic resonance imaging(BOLD-f MRI) and bispectral index(BIS) monitoring.Methods Forty-eight participants were enrolled at Peking Union Medical College Hospital from October 2011 to March 2012 and randomly assigned to a mild or a deep sedation group using computergenerated random numbers.Preliminary tests were performed a week prior to scanning to determine target effect site concentrations based on BIS and concomitant Observer's Assessment of Alertness/Sedation scores while under propofol.Within one week of the preliminary tests where propofol dose-response was established,BOLD-f MRI was conducted to examine brain activation with the subject awake,and with propofol infusion at the sedation level.Results Mild propofol sedation inhibited left inferior parietal lobe activation.Deep sedation inhibited activation of the left insula,left superior temporal gyrus,and right middle temporal gyrus.Compared with mild sedation,deep propofol sedation inhibited activation of the left thalamus,precentral gyrus,anterior cingulate,and right basal nuclei.Conclusion Mild and deep propofol sedation are associated with inhibition of different brain regions,possibly explaining differences in the respective loss of consciousness processes.
目的应用功能性磁共振成像技术定位机械性伤害性刺激诱发疼痛的脑区。方法健康男性志愿者20名，年龄20-40岁：体重指数18—25kg／m2，采用300gYonFrey纤维丝刺激志愿者左足心。1周后行功能性磁共振成像扫描，包括10s的初始采集信号扫描及静息态（208）与刺激态（20S）交替循环6次扫描。采用SPM2软件进行图像分析。结果300g von Frey纤维丝机械性伤害性刺激诱发疼痛的脑区包括：双侧前扣带回、右侧岛叶和双侧初级体感皮层。结论机械性伤害性刺激诱发疼痛的脑区包括双侧前扣带回、右侧岛叶和双侧初级体感皮层。
