Electrical Impedance Measures Physiological Changes in Skeletal Muscle Thickness

Tracking physiological changes in skeletal muscle thickness is a direct and unbiased approach in screening therapeutic compounds that prevent skeletal muscle atrophy or induce hypertrophy. In drug screening, it would be beneficial to find novel treatments that prevent muscle atrophy and other diseases associated with any morphologic change in cell shape.

Both qualitative and quantitative changes in electrical impedance as a function of cellular adhesion in real time correlated well with variation in myotube thickness caused by atrophy or hypertrophy agents. Conversely, pharmacologic blocking myotube hypertrophy prevented changes in electrical impedance.

Sergey Rakhilin PhD of Novartis (Basel, Switzerland) and colleagues used the xCELLigence system from Roche (Penzberg, Germany) to show that both qualitative and quantitative changes in electrical impedance as a function of cellular adhesion in real time correlate well with variation in myotube thickness caused by atrophy or hypertrophy agents. Conversely, pharmacologic blocking myotube hypertrophy prevented changes in electrical impedance. According to the study, impedance can be used as a reliable and sensitive biomarker for myotube atrophy or hypertrophy.

The study appeared online on April 14, 2011 in the Journal of Biomolecular Screening.

In the past, it was difficult to estimate accurate cell thickness for a couple of reasons. One is the extreme heterogeneity of the myotube cellular population and therefore the lack of a regular distribution of perturbed myotubes. Another reason is the fact that differentiated myotubes form a confluent layer, which makes it difficult to estimate parameters of individual cells. In addition, most of the atrophy or hypertrophy-induced changes in cell thickness are relatively small (less than twofold) and therefore hard to detect with low statistical error. Electrical impedance measurement overcomes these hurdles and offers a reliable method to determine cell thickness.

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