Prolonged activity evokes potentiation and the “sag” phenomenon in slow motor units of rat soleus

• Autorzy: Drzymala-Celichowska H. , Raikova R. , Krutki P.
• Języki publikacji: EN

Abstrakty

EN

Slow motor units (MUs) have no sag in their unfused tetani. This study in anesthetized rats shows that the sag can be observed in slow soleus MUs after prolonged activity. Twitches and unfused tetanic contractions were recorded from male (n=35) and female (n=39) MUs before and after the four minutes of the fatigue test (trains of 13 pulses at 40 Hz repeated every second). After this activity twitch contractions potentiated and a shift in the steep part of the force-frequency curve towards lower frequencies was observed in both sexes. Initially no sag was visible in unfused tetani, but after the fatigue test the phenomenon was observed in 77% of male and in 13% of female MUs, with the sex difference possibly related to a higher content of IIa myosin and faster MU contraction in male soleus. Decomposition of tetani with sag into trains of separate twitches elicited by successive stimuli revealed higher forces for the initial than subsequent twitches. The newly revealed enhancement of the sag in force development following long-lasting activation is more pronounced in males than in females.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2016
• Tom: 76
• Numer: 2
• Opis fizyczny: p.152-157,fig.,ref.

Twórcy

autor

Drzymala-Celichowska H.

• Department of Neurobiology, University School of Physical Education in Poznan, Poznan, Poland
• Division of Biochemistry, University School of Physical Education in Poznan, Poznan, Poland

autor

Raikova R.

• Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, Sofia, Bulgaria

autor

Krutki P.

• Department of Neurobiology, University School of Physical Education in Poznan, Poznan, Poland

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