Electrical impedance alterations in the rat hind limb with unloading

J Musculoskelet Neuronal Interact. 2013 Mar;13(1):37-44.

Abstract

Objectives: Methods are needed for quantifying muscle deconditioning due to immobilization, aging, or spaceflight. Electrical impedance myography (EIM) is one technique that may offer easy-to-follow metrics. Here, we evaluate the time course and character of the change in single- and multi-frequency EIM parameters in the hind-limb suspension model of muscle deconditioning in rats.

Methods: Sixty-two rats were studied with EIM during a two-week period of hind limb unloading followed by a two-week recovery period. Random subsets of animals were sacrificed at one-week time intervals to measure muscle fiber size.

Results: Significant alterations were observed in nearly all impedance parameters. The 50 kHz phase and multi-frequency phase-slope, created by taking the slope of a line fitted to the impedance values between 100-500 kHz, appeared most sensitive to disuse atrophy, the latter decreasing by over 33.0±6.6% (p<0.001), a change similar to the maximum reduction in muscle fiber size. Impedance alterations, however, lagged changes in muscle fiber size.

Conclusions: EIM is sensitive to disuse change in the rat, albeit with a delay relative to alterations in muscle fiber size. Given the rapidity and simplicity of EIM measurements, the technique could prove useful in providing a non-invasive approach to measuring disuse change in animal models and human subjects.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Electric Impedance
  • Hindlimb Suspension / methods*
  • Hindlimb Suspension / physiology*
  • Male
  • Random Allocation
  • Rats
  • Rats, Wistar