BK通道对大鼠脑缺血再灌注损伤神经细胞内钙离子浓度及凋亡的影响

目的 观察BK通道对脑缺血再灌注损伤神经细胞内钙离子浓度([Ca2+]i)和对神经元凋亡的影响。方法 将108只SD大鼠随机分为假手术组(SS组,n=36)、脑缺血再灌注组(IR组,n=36)、脑缺血再灌注且脑室内Iberiotoxin(IBTX)处理组(IBTX组,n=36),分别比较各组在不同再灌注时间后神经功能缺损评分、脑梗死面积,利用激光共聚焦显微镜技术测定各组[Ca2+]i浓度,免疫组织化学和TUNEL法分别检测BK通道表达和神经元细胞凋亡。结果 IBTX处理组在再灌注24h后神经功能缺损评分为(2.17±0.44)明显高于IR组(1.83±0.42,P＜0.05);脑梗死体积(27.97±5.84)％明显大于SS组(22.83±4.74)％(P＜0.05);激光共聚焦显微镜结果显示:IBTX处理组24h点[Ca2+]i为(914.50 ±86.57) nmol/L较SS组(732.09 ±51.30) nmol/L明显升高(P＜0.01),TUNEL细胞凋亡检测显示IBTX处理组24h神经细胞凋亡率为(15.20±6.11)％,与IR组(10.49±1.91)％比较差异有统计学意义(P＜0.05),免疫组织化学结果显示缺血再灌注损伤后BK通道的表达增加,但组间比较差异无统计学意义(P＞0.05)。结论 在缺血状态下,BK通道对神经细胞具有保护作用,其机制很可能是通过降低神经细胞内钙离子浓度和减少细胞的凋亡。

Regulation of BK channel on intracellular Ca2 + level and neuronal cells apoptosis after focal cerebral ischemia-reperfusion in rats

Objective To investigate the regulation of BK channel on intracelullar free calcium concentration[Ca2 +]i and apoptosis in neuronal cells in the rat brain following focalcerebral ischemia injury. Methods 108 SD rats were randomly assigned to sham group (n =36) , ischemic reperfusion group ( n =36), IBTX group ( n =36), compared neurological function defect and infarct size of different groups at the same reperfusing time. Laser scanning confocal microscope imaging of the calcium fluorescent indicator dye Fluo-2/AM was used to determine the changes of[Ca2+]i in neurons, the expression of BK tunnel was investigated by immunohistochemistry and neuronal cells apoptosis were measured by TUNEL. Results At 24 h after ischemic reperfusion, the neurological deficit scores in IBTX group were (2. 17 ± 0. 44),which obviously higher than ischemic reperfusion group ( 1.83 ± 0. 42, P ＜ 0.05 ) ;The brain infarct volume in IBTX group was (27. 97 ± 5.84 ) ％, which larger than ischemic reperfusion group ( 22. 83 ± 4. 74 ) ％( P ＜ 0. 05 ). The[Ca2 +]i and the cell apoptosis rate of IBTX group had significant difference at 24 h after ischemic reperfusion compared with ischemic reperfusion group: (914. 50 ± 86. 57 ) nmol/L VS (732. 09 ±51.30) nmol/L (P＜0. 01); (15.20±6. 11)％ vs (10.49±1.91)％ (P＜0.05).The results of immunohistochemistry indicate that the expression of BK channel in ischemic reperfusion group decreased, but the defference of three groups was not different significantly (P ＞ 0. 05). Conclusion BK channels could play a role in protecting the neuronal cells in mice following cerebral ischemia-reperfusion by inhibited the ascension of[Ca2+]i and decrease neurons apotosis.