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目的研究超低频复合生理频率慢性电刺激(lower physiological frequency chronic electrical stimulation,LPCES)对慢性低压缺氧兔颏舌肌肌球蛋白重链(myosin heavy chain,MHC)亚型表达和肌浆网(sarcoplasmic reticulum,SR)Ca2+摄取-释放动力学的影响。方法成年日本大白兔24只,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:2.5 Hz电刺激组,D:(2.5+40)Hz电刺激组。B、C、D组兔在构建慢性低压缺氧模型后,给予C、D 2组慢性电刺激,刺激频率分别为超低频2.5 Hz和超低频复合生理频率(2.5+40)Hz。采用Western blot分析4组兔颏舌肌MHC亚型表达变化,采用荧光光度测定法测定SR Ca2+摄取-释放动力学。结果①同正常对照组[(72.16±2.98)%]比较,慢性低压缺氧组[(80.45±1.26)%]兔颏舌肌MHCⅡa亚型比例明显增加(P<0.05),MHCⅠ亚型比例明显减少[(10.86±1.26)%vs(18.61±3.19)%,P<0.05],SR Ca2+摄取-释放速率明显下降,摄取-释放量也明显减少(P<0.05)。②同慢性低压缺氧组比较,慢性电刺激后各组兔MHCⅡa和MHCⅠ亚型比例明显增加(P<0.05),MHCⅡb亚型比例明显减少(P<0.05),(2.5+40)Hz电刺激组较2.5 Hz电刺激组更为显著(P<0.05);SR Ca2+摄取-释放速率加快,摄取-释放量增加(P<0.05),(2.5+40)Hz电刺激组较2.5 Hz电刺激组更为明显(P<0.05)。同2.5 Hz电刺激组比较,(2.5+40)Hz电刺激组MHCⅡa和MHCⅠ亚型比例差异无统计学意义(P>0.05)。结论慢性电刺激后慢性低压缺氧兔颏舌肌MHC呈现Ⅱb型向Ⅱa型和Ⅰ型的转变,SR Ca2+摄取-释放功能增强,其中超低频复合生理频率组变化更加明显。
Objective To investigate the effect of low-frequency complex physiological frequency chronic electrical stimulation (LPCES) on the expression of myosin heavy chain (MHC) subtype and sarcoplasmic reticulum, SR) Ca2 + uptake - release kinetics. Methods Twenty-four adult Japanese white rabbits were randomly divided into 4 groups (n = 6): A: normal control group, B: hypoxic hypoxia group, C: 2.5 Hz electrical stimulation group, D: 40) Hz electrical stimulation group. After chronic hypobaric hypoxia model was established in groups B, C and D, chronic electrical stimulation was given to rats in groups C and D at stimulation frequency of 2.5 Hz and ultra low frequency (2.5 + 40) Hz respectively. The expression of MHC subtypes in genioglossus muscle of four rabbits was detected by Western blot. The uptake and release kinetics of SR Ca2 + were measured by fluorimetry. Results ① Compared with the normal control group [(72.16 ± 2.98)%], the proportion of MHCⅡa subtype of genioglossus muscle in chronic hypobaric hypoxia group (80.45 ± 1.26%) was significantly increased (P <0.05), and the proportion of MHCⅠ subtype was significant (10.86 ± 1.26)% vs (18.61 ± 3.19)%, P <0.05]. The rate of uptake and release of SR Ca2 + significantly decreased (P <0.05). ②Compared with chronic hypobaric hypoxia group, the proportion of MHCⅡa and MHCⅠ subtypes increased significantly (P <0.05), MHCⅡb subtype decreased (P <0.05), (2.5 + 40) Hz electrical stimulation (P <0.05). The rate of uptake and release of SR Ca2 + increased (P <0.05), and the rate of uptake and release of SR Ca2 + increased (P <0.05). Compared with 2.5 Hz electrical stimulation group More obvious (P <0.05). Compared with the 2.5 Hz electrical stimulation group, there was no significant difference in the proportion of MHC Ⅱ a and MHC Ⅰ isoforms (2.5 ± 40) Hz electrical stimulation group (P> 0.05). Conclusion The MHC of genioglossus muscle of chronic hypobaric hypoxia model shows the transition from type Ⅱb to type Ⅱa and type Ⅰ after chronic electrical stimulation. The function of SR Ca2 + uptake and release is enhanced, especially in the ultra low frequency complex physiological frequency group.