Calcium sensitivity of skinned ferret EDL, soleus, and cremaster fibers.
Am J Physiol
; 264(5 Pt 2): R867-70, 1993 May.
Article
em En
| MEDLINE
| ID: mdl-8498595
The properties of the contractile system at different times of the year in the ferret extensor digitorum longus (EDL), soleus and cremaster muscles were examined by using chemically skinned (Triton X-100) preparations. The results show clear differences in calcium sensitivity between these skeletal muscles. The apparent calcium threshold for activation was lower in soleus than in EDL, while calcium concentrations ([Ca2+]) required to obtain the half-maximal tension, expressed as pCa50 (-log[Ca2+]), was lower in EDL than in soleus muscle. In fact, pCa50 obtained in fast and slow fibers by fitting the experimental data points by a modified Hill equation was 5.92 +/- 0.02 (n = 9) and 6.09 +/- 0.03 (n = 11) respectively. So EDL appears to be a typical fast-twitch muscle and soleus a typical slow-twitch muscle. Adult ferret cremaster muscle was composed of two types of fibers during the quiescent period similar to EDL and soleus, and only one type that was intermediate between EDL and soleus in the breeding period, as assessed by pCa50 values. These annual modifications in calcium activation of adult ferret cremaster muscle could be related to changes in the function of these muscles and may be correlated with seasonal variations of sexual activity.
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Bases de dados:
MEDLINE
Assunto principal:
Cálcio
/
Furões
/
Contração Muscular
/
Músculos
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
Am J Physiol
Ano de publicação:
1993
Tipo de documento:
Article
País de afiliação:
França