The state of urethral musculature during the detrusor areflexia after spinal cord transection.

The state of the urethral musculature was studied using the urethral pressure profile and electromyographic recording in periurethral striated muscle. In dogs under chloralose anesthesia a micturition reflex could be elicited by bladder distension and somatic reflexes could be elicited by various stimuli. Both the urethral profile and electromyographic activity could be recorded immediately after surgical transection of the spinal cord between T2 and T8 but the bladder remained areflexic for more than 12 hr. Pharmacologic analysis of the urethral pressure profile revealed a substantial contribution from both sympathetic and somatic components. The periurethral striated musculature usually responded to bladder filling in a similar manner both before and after transection, although there was no bladder contraction in the latter circumstance. It is concluded that the urethra does not experience the same depression of reflex activity as does the bladder in the acute stage after spinal cord transection.