Urethral responses during selective electrostimulation of lumbosacral spinal nerve roots in the female spinal dog.

Urethral responses on the urethral pressure profile (UPP) during selective electrostimulation of the ventral or dorsal roots in a group of lower lumbar (L5-7) or sacral (S1-3) nerves were observed in female spinal (C1-transected) dogs. The UPPs were recorded by using a balloon catheter, and square pulse wave of 5 V, 10 Hz, 1 msec was applied for electrostimulation of the spinal nerve root. The UPPs were analyzed by dividing the functional profile length (FL) into three equal parts and comparing the height of maximal clossure pressure at each UPP segment. After lumbosacral rhizotomies proximal to the electrodes, stimulation of the lower lumbar ventral roots produced a marked elevation at the proximal third (bladder neck) of UPP, while similar response was found at the middle third (midsphincteric urethra) and distal third (external urethral sphincter) of UPP during the sacral ventral roots stimulation. The stimulation of the dorsal roots of the lower lumbar and sacral nerves also produced a similar response as that of the ventral roots stimulation though less in amplitude. So it could be concluded that in female dog the sphincteric urethra might receive a functional innervation from the lower lumbar and sacral spinal segments in somewhat different manners.