This work investigated the role of extracellular Ca2+ in high-frequency fatigue (HFF) in slow and fast skeletal muscles of mice. The study was performed in both innervated and 14-day denervated soleus and EDL muscles of CD1 mice (3 months old). In nominally external Ca2+ free solution, fatigue significantly increased in normal soleus but not in EDL muscles. Interestingly, 14 days after denervation HFF was not affected by external Ca2+ in soleus, while it was significantly increased in EDL muscles. The possible involvement in HFF development of store-operated Ca2+ channels, mechano-sensitive or stretch-activated cation channels, L-type voltage-gated Ca2+ channels, sphingolipidgated Ca2+ channels and of P2X receptors was investigated by using specific inhibitors. The protective action of extracellular Ca2+ in HFF appears to involve the activation of P2X receptors.
High-frequency fatigue of innervated and denervated muscles: role of cell membrane calcium channels
GERMINARIO, ELENA;DANIELI, DANIELA
2004
Abstract
This work investigated the role of extracellular Ca2+ in high-frequency fatigue (HFF) in slow and fast skeletal muscles of mice. The study was performed in both innervated and 14-day denervated soleus and EDL muscles of CD1 mice (3 months old). In nominally external Ca2+ free solution, fatigue significantly increased in normal soleus but not in EDL muscles. Interestingly, 14 days after denervation HFF was not affected by external Ca2+ in soleus, while it was significantly increased in EDL muscles. The possible involvement in HFF development of store-operated Ca2+ channels, mechano-sensitive or stretch-activated cation channels, L-type voltage-gated Ca2+ channels, sphingolipidgated Ca2+ channels and of P2X receptors was investigated by using specific inhibitors. The protective action of extracellular Ca2+ in HFF appears to involve the activation of P2X receptors.
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