Dermatome mapping in the rat hindlimb by electrical stimulation of the spinal nerves.

In rats treated with Evans blue (i.v.), electrical stimulation of the lumbar spinal nerves produced an extravasation zone in the skin. Stimulation of L1 produced extravasation in the lower abdomen; that of L2, in the cranial region of the hindlimb; that of L3, in the ventral region of the hindlimb and the medial paw; that of L4, in the lateral region of the hindlimb and the middle paw; that of L5, in the caudal region of the hindlimb and the lateral paw; and that of L6, in the caudal region of the hindlimb and the scrotum. Since the substance P antagonist FK224 inhibited the extravasation caused by stimulation of the sciatic nerve, the extravasation zones appeared to be related to antidromic activation of afferent C-fibers. Thus, a dermatome of afferent C-fibers was revealed in rats.