Electrical stimulation at lower physiological frequency induces myosin heavy chain isoform transformation and improves sarcoplasmic reticulum Ca2+ uptake/release in genioglossus of rabbits exposed to chronic hypoxia
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Electrical stimulation at lower physiological frequency induces myosin heavy chain isoform transformation and improves sarcoplasmic reticulum Ca2+ uptake/release in genioglossus of rabbits exposed to chronic hypoxia
Journal of Army Medical UniversityVol. 33, Issue 7, Pages: 690-694(2011)
Liu Xi,Liu Gang,Zhang Ni,Ou Na,Zhang Peng.Electrical stimulation at lower physiological frequency induces myosin heavy chain isoform transformation and improves sarcoplasmic reticulum Ca2+ uptake/release in genioglossus of rabbits exposed to chronic hypoxia[J].J Amry Med Univ (J Third Mil Med Univ),2011,33(07):690-694.
Liu Xi,Liu Gang,Zhang Ni,Ou Na,Zhang Peng.Electrical stimulation at lower physiological frequency induces myosin heavy chain isoform transformation and improves sarcoplasmic reticulum Ca2+ uptake/release in genioglossus of rabbits exposed to chronic hypoxia[J].J Amry Med Univ (J Third Mil Med Univ),2011,33(07):690-694.DOI:
Electrical stimulation at lower physiological frequency induces myosin heavy chain isoform transformation and improves sarcoplasmic reticulum Ca2+ uptake/release in genioglossus of rabbits exposed to chronic hypoxia
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)Ca
2+
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 Ca
2+
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(P0.05),MHCⅠ亚型比例明显减少[(10.86±1.26)% vs (18.61±3.19)%,P0.05
]
,SR Ca
2+
摄取-释放速率明显下降,摄取-释放量也明显减少(P0.05)。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(P0.05),MHCⅡb亚型比例明显减少(P0.05),(2.5+40)Hz电刺激组较2.5 Hz电刺激组更为显著(P0.05);SR Ca
2+
摄取-释放速率加快,摄取-释放量增加(P0.05)
(2.5+40)Hz电刺激组较2.5 Hz电刺激组更为明显(P0.05)。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(P0.05)。 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 Ca
2+
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。
Abstract
Objective To identify the effect of chronic electrical stimulation at a lower physiological frequency on the expressions of myosin heavy chain (MHC) isoforms and kinetics of sarcoplasmic reticulum (SR) Ca
2+
uptake/release in the genioglossus of rabbits exposed to chronic hypoxia. Methods Twenty-four adult rabbits were randomized into control group (A)
chronic hypoxia group (B)
2.5 Hz electrical stimulation group (C) and (2.5+40) Hz electrical stimulation group (low frequency plus physical frequency
D). After the rabbits from group B
C and D had been fed with free access to food and water in a hypoxia cabin (simulating 5 000 m altitude) in 10 h a day for 4 weeks
the rabbits in group C and D received electrical stimulation in their genioglossus at a frequency of 2.5 Hz and (2.5+40) Hz respectively in 10 h per day for 14 d
while those in group B received no electrical stimulation. Expressions of MHC isoforms in the genioglossus of rabbits in 4 groups were detected by Western blotting
and Fura-2 fluorophotometry was used to assay the kinetics changes of SR Ca
2+
uptake-release. Results The expression level of MHCⅡa was significantly higher while that of MHCⅠ was significantly lower in group B than that in group A (P0.05). Meanwhile
the genioglossus SR Ca
2+
uptake/release velocity in group B was significantly decreased compared with that in group A (P0.05). The expression levels of MHCⅡa and MHCⅠ in group C and D after electrical stimulation were significantly higher
while those of MHCⅡb
especially in group D
were significantly lower than those in group B (P0.05). The genioglossus SR Ca
2+
uptake/release velocity in group C and D
especially in group D
was significantly increased compared with that in group B (P0.05). No significant difference was found in expression levels of MHCⅡa and MHCⅠ between group C and D after electrical stimulation (P0.05). Conclusion MHCⅡb in the genioglossus of rabbits with chronic hypoxia is tr
ansformed to MHCⅡa and MHCⅠ after electrical stimulation
and SR Ca
2+
uptake/release velocity is increased
especially at a lower physiological frequency of (2.5+40) Hz.