CONSISTENT REPEATED M-WAVE AND H-WAVE RECORDING IN THE HIND-LIMB OF RATS

Sensory and motor conduction velocities calculated from latencies of H reflexes and M waves in rat hind limbs have been used to assess exper imental peripheral neuropathy. Amplitudes and latencies vary with reco rding location, and are seldom assessed directly. Using subcutaneous e lectrodes on the foot, we recorded consistent M waves and H reflexes w hile stimulating the sciatic or tibial nerve. The late wave disappeare d when dorsal roots were cut, verifying that it was an H reflex, Howev er, stimulus-response characteristics differed from those in humans: ( a) the threshold was often higher than for M waves; (b) stimulus inten sity eliciting a maximum H-reflex amplitude (H-max) was often higher t han adequate for a maximum M-wave amplitude; and (c) the amplitudes of H reflexes stimulated with intensities supramaximal for the M wave we re over 90% of H-max. H reflexes and M waves recorded repeatedly in ra ts can be useful in assessing sensory and motor function in models of neuropathy, using amplitudes as well as conduction velocities. (C) 199 8 John Wiley & Sons, Inc. Muscle Nerve 21: 1405-1413, 1998.