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目的研究低频复合生理频率慢性电刺激对低压缺氧兔颏舌肌肌球蛋白重链(myosin heavy chain,MHC)亚型表达的影响。方法成年日本大白兔24只,雌雄不拘,体质量(2.3±0.1)kg,按随机数字表法分为4组(n=6)。A:正常对照组,B:慢性低压缺氧组,C:10Hz电刺激组,D:10+40Hz电刺激组。B、C、D组兔置于慢性低压缺氧环境中饲养后,分别给予C组兔颏舌肌低频(10Hz)电刺激,D组兔颏舌肌低频复合生理频率(10+40Hz)电刺激,B组兔不予电刺激。采用SDS-聚丙烯酰胺凝胶电泳及半定量反转录聚合酶链式反应(RT-PCR)法,分析4组颏舌肌MHC各亚型表达变化。结果①与正常对照组比较,慢性低压缺氧组颏舌肌MHCⅠ亚型比例减少[(0.69±0.07)%vs(17.48±4.00)%,P<0.05],MHCⅡa亚型比例增加[(79.89±5.09)%vs(73.33±4.17)%,P<0.05];MHCⅠ亚型mRNA表达量下降[(0.69±0.07)vs(1.05±0.06),P<0.05]。②与慢性低压缺氧组比较,10Hz电刺激组颏舌肌MHCⅠ亚型比例[(18.78±3.49)%vs(11.37±4.27)%,P<0.05]及10+40Hz电刺激组颏舌肌MHCⅠ亚型比例[(23.40±4.65)%vs(11.37±4.27)%,P<0.05]均增加,而10+40Hz电刺激组颏舌肌MHCⅡa亚型比例[(67.90±5.66)%vs(79.89±5.09)%,P<0.05]减少;与慢性低压缺氧组比较,10Hz电刺激组颏舌肌MHCⅠ亚型mRNA表达量[(0.79±0.07)vs(0.69±0.07),P<0.05]及10+40Hz电刺激组颏舌肌MHCⅠ亚型mRNA表达量[(0.97±0.08)vs(0.69±0.07),P<0.05]均增高,而MHCⅡa亚型mRNA表达量差异不显著。结论慢性电刺激后低压缺氧兔颏舌肌MHC呈现Ⅱa向Ⅰ型转变,即“由快向慢”转变。其中低频复合生理频率电刺激组变化的趋势更加明显。
Objective To investigate the effect of low frequency, complex physiological frequency chronic electrical stimulation on the expression of myosin heavy chain (MHC) subtypes in hypobaric hypoxia rabbits. Methods Twenty-four adult Japanese white rabbits were randomly divided into 4 groups (n = 6). The body weight was (2.3 ± 0.1) kg. A: normal control group, B: hypoxic hypoxia group, C: 10Hz electrical stimulation group, D: 10 + 40Hz electrical stimulation group. B, C, D rabbits were housed in chronic hypoxia environment, and then were given low frequency (10Hz) electrical stimulation of genioglossus muscle in group C and low frequency complex physiological frequency (10 + 40Hz) electrical stimulation of genioglossus muscle in group D , Rabbits in group B did not receive electrical stimulation. SDS-polyacrylamide gel electrophoresis and semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) were used to analyze the expression changes of MHC in four genioglossus muscles. Results Compared with the normal control group, the proportion of MHCⅠ subtype in genioglossus muscle was significantly decreased in chronic hypobaric hypoxia group [(0.69 ± 0.07)% vs (17.48 ± 4.00)%, P <0.05] 5.09)% vs (73.33 ± 4.17)%, P <0.05]. The mRNA expression level of MHCⅠin subtype decreased (0.69 ± 0.07) vs (1.05 ± 0.06), P <0.05. ② Compared with chronic hypobaric hypoxia group, the proportion of MHCⅠ subtype in genioglossus muscle in 10Hz group [(18.78 ± 3.49)% vs (11.37 ± 4.27)%, P <0.05] and 10 + 40Hz group The proportion of MHCⅡa was significantly higher in genioglossus muscle of 10 + 40 Hz group ([(23.40 ± 4.65)% vs (11.37 ± 4.27)%, P <0.05] 5.09)%, P <0.05]. Compared with chronic hypobaric hypoxia group, the expression of MHC I subtype mRNA in genioglossus muscle in 10Hz group was significantly lower than that in chronic hypobaric hypoxia group [(0.79 ± 0.07) vs (0.69 ± 0.07), P <0.05] The expression of MHC Ⅰ subtype mRNA in genioglossus muscle of + 40 Hz electrical stimulation group was significantly higher than that of normal group ([(0.97 ± 0.08) vs (0.69 ± 0.07), P <0.05], while the MHCⅡa mRNA expression level was not significantly different. Conclusion The MHC of genioglossus muscle in hypobaric hypoxia after chronic electrical stimulation shows the transition from type Ⅱa to type Ⅰ, that is, “from fast to slow”. In which low-frequency composite physiological frequency electrical stimulation group more obvious trend of change.