Description and validation of isometric tetanic muscle force test in rabbits

Abstract

Isometric tetanic muscle force has been described in a rat model to evaluate motor recovery in a segmental sciatic nerve defect reconstructions. However, to test longer nerve defects, an alternative and larger animal model is necessary. The purpose of this study is to describe and validate a technique for isometric force measurement of the tibialis anterior (TA) muscle in New Zealand rabbits. Muscle preload and electrical stimulation parameters were optimized to obtain the highest tetanic contraction bilaterally in 10 animals. Electrophysiology, muscle weight, peroneal nerve length, and histomorphometry were also analyzed. Only the peroneal nerve length and the ratio of highest muscle force/muscle weight demonstrated the equivalence between the sides. A small variability of TA muscle force and TA muscle weight was observed between the sides suggesting dominance. Optimization of electrical stimulation and preload as well as the use of correct anesthesia were fundamental to acquire the highest muscle force.

Motor Nerve Recovery in a Rabbit Model: Description and Validation of a Noninvasive Ultrasound Technique

“…4,15 Recovery of more than 100% ITF is in line with previously reported data and may be explained by a side preference in the rabbit. 4,9,15,25 This method can be used for other nerves and innervated muscles including brachial plexus injury models. The noninvasive nature allows for longitudinal follow-up and measurement of early recovery, and provides a useful tool for comparative studies of nerve reconstruction strategies.…”

“…This is in line with previous studies that used CMAP in rabbits. 4,15 Previous studies validated muscle cross-sectional area measurement by ultrasound for both the gastrocnemius and tibial muscle in rats. 7,9 In the rabbit, typically only the peroneal branch, innervating the tibialis anterior muscle, instead of the entire sciatic nerve, is grafted.…”

“…The variability of the other outcome measurements was based on previous studies. 4,15 Assuming the same variability would occur in this study, the number of animals needed for 80% power to detect a correlation of at least 0.65 reliably was calculated to be 12.…”

“…Propofol was used in lieu of isoflurane, which has been shown to interfere with skeletal muscle contraction. 4,13 Dextrose 5% was administered intravenously to prevent muscle fatigue.…”

“…3 Those limitations can be overcome using rabbits, in which nerve gaps up to 8 cm are feasible. 4 Furthermore, the rabbit's neuroregenerative and immunological properties more closely mimic the human situation, providing an important step before clinical research. 5,6 To evaluate motor nerve recovery after nerve reconstruction in both rat and rabbit, the easily obtainable wet muscle weight is frequently used.…”