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. 2009 Aug;120(8):1534-8.
doi: 10.1016/j.clinph.2009.05.017. Epub 2009 Jun 30.

Electrical impedance myography at 50kHz in the rat: technique, reproducibility, and the effects of sciatic injury and recovery

Mohammad A Ahad  1 , Seward B Rutkove
Affiliations

Electrical impedance myography at 50kHz in the rat: technique, reproducibility, and the effects of sciatic injury and recovery

Mohammad A Ahad et al. Clin Neurophysiol. 2009 Aug.

Abstract

Objective: To describe a refined technique for performing electrical impedance myography (EIM) in the rat and assess its reproducibility, long-term stability, and the effects of sciatic nerve injury.

Methods: EIM at 50kHz was performed on the gastrocnemius-soleus complex of the rat hind limb in 12 rats, followed from 6 weeks of age for up to 6 months. Eight additional rats underwent sciatic nerve crush and 6 underwent a sham procedure.

Results: The EIM variables of resistance, reactance and phase demonstrated substantial change with growth until approximately 14 weeks of age, at which point the measurements stabilized, giving mean values of 6.0+/-5.7Omega, 22.1+/-2.1Omega, and 16.5+/-1.1 degrees , respectively, at 16 weeks of age. Immediate reproducibility of technique was high with an intraclass correlation coefficient of 0.91 and higher for all three parameters. Sciatic crush produced marked reductions in the reactance and phase that reversed over a several week period.

Conclusions: These results support that 50kHz EIM can be performed effectively in adult rat models of neuromuscular disease with a straightforward experimental technique and that it is sensitive to neurogenic injury.

Significance: EIM can serve as a new approach to the study of neuromuscular disease in the rat.

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Figures

Figure 1
Figure 1
Rat EIM measurement set-up. The small dot in the center of the electrode array represents the tattoo used as a landmark for repeated positioning of the array.
Figure 2
Figure 2
Change of weight and girth at the tattoo position over time.
Figure 3
Figure 3
Resistance (a), reactance (b), and phase (c) data of the rats, from 6 weeks of age onward. Note gradual reduction in reactance and resistance up to approximately 14 weeks of age, followed by excellent stability over the ensuing several months.
Figure 3
Figure 3
Resistance (a), reactance (b), and phase (c) data of the rats, from 6 weeks of age onward. Note gradual reduction in reactance and resistance up to approximately 14 weeks of age, followed by excellent stability over the ensuing several months.
Figure 4
Figure 4
Immediate reproducibility of the EIM measurements of resistance (a), reactance (b), and phase (c) for the 12 rats. ICC, intraclass correlation coefficient
Figure 5
Figure 5
Resistance (a), reactance (b), and phase (c) data in adult rats undergoing sciatic crush (solid line) and sham surgery (dashed line).
See this image and copyright information in PMC

References

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