The concentrations of the six kinds of muscle fiber type-specific proteins (B-subunit of creatine kinase, CKB; S-100a
0;αB-crystaline;β-subunit of enolase, β-enolase; M-subunit of creatine kinase, CKM: parvalbumin) were measured in the rat tongue, fast muscle (ensor digitorum longus) and slow muscle (soleus) in the hindlimb. The effect of the complete severance of the lateral hypoglossus nerve was also examined in the tongue.
The following results were obtained:
1) The concentrations of CKB, localized mainly in type I fibers in the tongue, were extremely high, while those of S-100a
0 and αB-crystaline, localized mainly in type I fibers in the tongue, were comparable to the values in the EDL.
2) The concentrations of β-enolase, CKM and parvalbumin, localized mainly in type II fibers in the tongue, were comparable to those in the SOL.
3) After denervation of the tongue, the concentrations of β-enolase and CKM decreased, whereas those of CKB and parvalbumin increased until the 6th postopeative week. After the 12th week, there was a tendency to return to the normal level, possibly due to recovery of muscle function associated with reinnervation.
4) The concentrations of S-100a
0 and αB-crystalin were not affected by denervation.
It was concluded that: 1) The tongue is composed of mixed fiber type, exhibiting type I fiber factors of muscle fiber type-specific proteins; 2)β-enolase, CKB, CKM and parvalbumin can be good markers of tongue muscle condition after nerve injury.
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