四种静脉麻醉药物对大鼠皮层脑片缺氧缺糖损伤的作用

目的 探讨四种常用静脉麻醉药物对大鼠皮层脑片缺氧缺糖损伤的作用。方法 建立大鼠皮层脑片缺氧缺糖损伤模型,设立对照组、缺氧缺糖损伤组、药物加损伤组,利用2,3,5-三苯基氯化四氮唑(TTC)染色定量比色方法,评价氯胺酮、异丙酚、咪达唑仑和硫喷妥钠对脑片损伤的保护作用。结果 随着缺氧缺糖损伤时间的延长,皮层脑片TTC染色程度明显降低,TTC染色反映的组织损伤百分率与孵育上清液乳酸脱氢酶(LDN)释放比活性呈正相关(r=0.9609,P<0.01)。对于缺氧缺糖损伤所致脑片TTC染色降低,不同浓度氯胺酮均能完全抑制;与损伤组比较。大剂量硫喷妥钠和咪达唑仑(400μmol·L~(-1)和10μmol·L~(-1)A值明显升高(P<0.01或0.05);小剂量异丙酚(1μmol·L~(-1))对脑片TTC染色降低无作用,大剂量(100μmol·L~(-1))加重TTC染色降低(P<0.01)。结论 对于大鼠皮层脑片缺氧缺糖损伤,四种静脉麻醉药物作用效果各不相同:临床麻醉剂量的氯胺酮具有明显保护作用,咪达唑仑和硫喷妥钠在超过临床使用范围的大剂量时有部分保护作用;大剂量异丙酚会加重大鼠皮层脑片的缺氧缺糖损伤。

The effects of four intravenous anesthetics on the damage caused by oxygen-glucose deprivation in rat cortical slices

Objective To compare the effects of different concentrations of ketamine, propofol, midazolam and thiopental on brain ischemic damage caused by oxygen-glucose deprivation (OGD) in rat cortical slices. Methods Male SD rats weighing 90-100 g were decapitated and brain was immediately removed and submerged in normal artificial cerebro-spinal fluid (nACSF) saturated with 95 % O2+ 5 % CO2 . Cortical slices (400 um thick) were made and divided into 3 groups : (1) control group in which cortical slices were incubated in nACSF at 371 ;(2) OGD group in which cortical slices were incubated in artificial CSF deprived of glucose and saturated with 95 % N2+5 % CO2 for 5, 10, 15, 30 and 60 min respectively to determine the brain damage caused by different duration of ischemia; (3) intravenous anesthetic + OGD group in which three different concentrations of ketamine (5,10, 50 umol. L-1) , midazolam (0.5, 1, 10 umol. L-1 ), thiopental (25, 100, 400umol.L-1 ) and propofol ( 5, 50,100umol.L-1 ) were added to cortical slices incubated in nACSF and 30 min before and during 10 min OGD to detennine the effects of the different concentrations of the four intravenous anesthetics on (a) normal cortical slices and (b) damage caused by 10 min OGD prophylactically and therapeutically. The damage caused by OGD was evaluated by extracted formazan (reduced nitroblue tetrazolam with dark blue color) after being incubated in 2% 2, 3, 5-tripbenyl tetrazolium chloride (TTC) solution after OGD and LDH leakage after OGD. Results With increasing duration of OGD, the fonnazan coloration was decreasing. The percentage of tissue injury calculated from TTC staining was positively correlated with the leakage of LDH ( r= 0.9609, P < 0.01). Ketamine completely abolished the decrease in TTC staining induced by OGD insult. Midazolam and thiopental inhibited the decrease in TTC staining only at high concentration (midazolam 10 umol. L-1 ; thiopental 400umol. L-1 ). Propofol had no effect on TTC staining at low concentration but enhanced the decrease in TTC staining at high concentration ( 100umol. L-1 ) . Conclusion Different intravenous anesthetics have different effects on damage caused by OGD in rat cortical slices. Ketamine protects brain from the injury completely. Midazolam and thiopental exert a protective effect only at concentration higher than clinical dosage. Propofol worsens the OGD injury at high concentration.