Adaptation of motoneurons to altered physical activity

• Autorzy: Krutki P.
• Języki publikacji: EN

Abstrakty

EN

The study shows that different models of an increased muscular activity may induce measurable effects on electrophysiological properties of motoneurons (MNs). Three types of altered motor activity were compared in rats: chronic compensatory muscle overload, whole-body vibration (WBV), and strength training. Intracellular recordings from spinal motoneurons were made to measure membrane and firing properties of MNs.Muscle overload was induced in the rat medial gastrocnemius by bilateral tenotomy of its synergists. Adaptive changes in passive and threshold properties were observed only in fast-type MNs innervating the overloaded muscle. The data suggest their higher excitability, and a shift towards electrophysiological properties of slow-type Mns. The WBV training was performed 5 days a week, for 5 weeks, and each daily session consisted of four 30-second runs of vibration at 50 Hz. No significant changes in the passive membrane properties of MNs were found after the WBV program. However, lower values of rheobase current and a leftward shift of the frequencycurrent relationship were observed for fast-type MNs. This indicates their ability to become recruited earlier (and possibly more frequent), and to achieve the same or higher firing rates at lower stimulus intensities. During strength training rats were nutritionally conditioned in order to make weightlifting put on their shoulder in a special apparatus with progressively increasing load. After 5 weeks adaptive changes in several membrane properties were revealed in fast and slow-type MNs. Increased maximum frequencies of rhythmic firing of MNs, and higher susceptibility of MNs to an increased or decreased intensity of a stimulus were observed. Adaptations of MNs to various modes of chronic activation of muscles were relatively quick, but different with respect to extent and dynamics of the effects. Supported by the National Science Center grants: 2011/01/N/ NZ4/04901, 12/04/M/NZ4/00190 and 2013/11/B/NZ7/01518.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2015
• Tom: 75
• Numer: Supl.
• Opis fizyczny: p.S30

Twórcy

autor

Krutki P.

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