Effects of electrical stimulation of motor and cutaneous nerves on spinal cord blood flow

The effects of electrical stimulation of the motor and cutaneous branch of the radial nerve on spinal cord blood flow (SCBF) in the cervical region and the correlation between the changes in SCBF and the amplitudes of spinal cord evoked potentials were investigated in cats anesthetized with alpha-chloralose. When measured by the hydrogen clearance technique, with stimuli of the cutaneous branch, the SCBF significantly (P < 0.01) increased from 37 +/- 8 (mean +/- SD) to 59 +/- 27 ml.100 g-1.min-1 at 10 Hz and from 39 +/- 6 to 54 +/- 9 ml.100 g-1.min-1 at 30 Hz, but stimulation of the motor branch had no effect. When measured by laser Doppler flowmetry, stimulation of the motor branch caused a small, transient, and significant increase in SCBF ending within 2 minutes. Stimulation of the cutaneous branch produced a large, prolonged, and significant increase in SCBF. The increase in SCBF produced by stimulation of the cutaneous nerve was significantly greater than that by stimulation of the motor branch. The SCBF was correlated linearly with the amplitude of the spinal cord evoked potential (r = 0.504; P < 0.01). The increase in SCBF caused by radial nerve stimulation may arise from changes in neuronal metabolism via peripheral nerve activation.