Sex differences in the decomposition of motor unit tetanic contractions of rat soleus muscle

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

Abstrakty

EN

BACKGROUND AND AIMS: The aim of this study was to reveal variability of twitch-shape decomposed components of motor unit tetanic contractions of rat soleus muscle, which is almost exclusively composed of slow motor units (MUs). Moreover, sex differences in ranges of the force amplitude or time parameters of these decomposed twitches were analyzed. METHODS: Experiments were performed on adult Wistar rats (three males and three females) under general anesthesia. Functional isolation of a MU was achieved by electrical stimulation of single axons from the ventral roots of L4–L5 spinal nerves. Unfused tetanic contractions were evoked by stimulation at variable interpulse intervals for 10 MUs of males and 10 MUs of females. RESULTS: Significantly higher variability between parameters of the decomposed responses was observed for male than female soleus MUs; the mean ratio of forces of the strongest decomposed twitch to the first (the weakest) decomposed twitch amounted to 3.8 for males and 2.8 for females. The ratios of the contraction times of the longest decomposed to the first twitch were less different, and amounted to 2.6 for male and 2.9 for female MUs. Consequently, the mean ratio of the force-time area for the strongest decomposed to the first twitch was considerably higher for male than for female MUs (7.35 vs. 5.07, respectively). The comparison to the data for slow or fast MUs in rat medial gastrocnemius indicates that high variability of responses to successive stimuli is a general property of slow MUs, but the mechanisms of summation of individual twitches into tetanic contractions of MUs are sex-related. CONCLUSIONS: A method of mathematical decomposition of tetanic contractions appears to be a useful and an effective tool to study differences in mechanisms of MU force development between different MU types, the same MU types in different muscles or the same muscles in different sexes.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2015
• Tom: 75
• Numer: Supl.
• Opis fizyczny: p.S71

Twórcy

autor

Drzymala-Celichowska H.

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

autor

Celichowski J.

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