Kalhovde J M, Jerkovic R, Sefland I, Cordonnier C, Calabria E, Schiaffino S, Lømo T
Department of Physiology, PO Box 1103, Blindern, 0317 Oslo, Norway.
J Physiol. 2005 Feb 1;562(Pt 3):847-57. doi: 10.1113/jphysiol.2004.073684. Epub 2004 Nov 25.
Myosin heavy chain (MyHC) expression was examined in regenerating fast extensor digitorum longus (EDL) and slow soleus (SOL) muscles of adult rats. Myotoxic bupivacaine was injected into SOL and EDL and the muscles were either denervated or neuromuscularly blocked by tetrodotoxin (TTX) on the sciatic nerve. Three to 10 or 30 days later, denervated SOL or EDL, or innervated but neuromuscularly blocked EDL received a slow 20 Hz stimulus pattern through electrodes implanted on the muscles or along the fibular nerve to EDL below the TTX block. In addition, denervated SOL and EDL received a fast 100 Hz stimulus pattern. Denervated EDL and SOL stimulated with the same slow stimulus pattern expressed different amounts of type 1 MyHC protein (8% versus 35% at 10 days, 13% versus 87% at 30 days). Stimulated denervated and stimulated innervated (TTX blocked) EDL expressed the same amounts of type 1, 2A, 2X and 2B MyHC proteins. Cross-sections treated for in situ hybridization and immunocytochemistry showed expression of type 1 MyHC in all SOL fibres but only in some scattered single or smaller groups of fibres in EDL. The results suggest that muscle fibres regenerate from intrinsically different satellite cells in EDL and SOL and within EDL. However, induction by different extrinsic factors arising in extracellular matrix or from muscle position and usage in the limb has not been excluded. No evidence for nerve-derived trophic influences was obtained.
在成年大鼠再生的快肌趾长伸肌（EDL）和慢肌比目鱼肌（SOL）中检测了肌球蛋白重链（MyHC）的表达。将具有肌毒性的布比卡因注入SOL和EDL，然后通过对坐骨神经进行去神经支配或用河豚毒素（TTX）进行神经肌肉阻滞。3至10天或30天后，对去神经支配的SOL或EDL，或神经支配但经神经肌肉阻滞的EDL，通过植入肌肉上或沿腓骨神经至TTX阻滞下方的EDL的电极施加20 Hz的缓慢刺激模式。此外，对去神经支配的SOL和EDL施加100 Hz的快速刺激模式。以相同的缓慢刺激模式刺激的去神经支配的EDL和SOL表达不同量的1型MyHC蛋白（10天时分别为8%和35%，30天时分别为13%和87%）。受刺激的去神经支配的和受刺激的神经支配（TTX阻滞）的EDL表达相同量的1型、2A型、2X型和2B型MyHC蛋白。经原位杂交和免疫细胞化学处理的横截面显示，1型MyHC在所有SOL纤维中表达，但仅在EDL中一些分散的单个或较小的纤维群中表达。结果表明，肌肉纤维从EDL和SOL以及EDL内本质上不同的卫星细胞再生。然而，尚未排除细胞外基质中产生的不同外在因素或肢体中肌肉位置和使用情况的诱导作用。未获得神经源性营养影响的证据。
