AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 2 284-R291, Copyright © 1989 by American Physiological Society
Urethral responses to sacral stimulation in chronic spinal dog
J. S. Walter, J. S. Wheeler, C. J. Robinson, T. Khan and R. D. Wurster
Hines Veterans Affairs Hospital, Rehabilitation Research and Development Center 60141.
Urethral activity was investigated in the awake chronic spinal-injured
canine using urodynamic recordings, video cystofluoroscopy, and urethral
pressure recordings without anesthesia. Bladder contractions and voiding
were induced by electrical stimulation with epidural electrodes inserted
into the sacral canal. Urethral pressure remained elevated during
stimulation and for 1-3 s afterward. Poststimulation voiding occurred with
three different patterns: 1) pulsatile voiding in which squirting of urine
was associated with contractions in the membranous urethra; 2) "on and off"
voiding in which pulsatile flow was interrupted for brief periods of time;
and 3) steady-stream voiding in which nonpulsatile flow was followed by
pulsatile flow. Viewing these voiding patterns with fluoroscopy indicated
that the proximal membranous urethra was important in all of the patterns.
We conclude that in the chronic spinal-injured canine the skeletal muscle
within the membranous urethra (rhabdosphincter) is involved in responses to
sacral stimulation and various voiding patterns.
