Functional contribution of autonomic innervation to urethral striated sphincter: studies with parasympathomimetic, parasympatholytic and alpha-adrenergic blocking agents in spinal cord injury and control male subjects.

Mechanisms underlying urethral pressure changes at the external sphincter region after administration of neuropharmacologic agents were investigated with cystosphincterometric studies and electromyography of the external urethral sphincter in adult patients with spinal cord injury and control male subjects. Bethanechol chloride, propantheline or phentolamine were administered to 37 spinal cord injury men and 3 normal controls. After cystectomy 3 additional spinal cord injury patients were subjected to bethanechol studies. The results of these studies suggested that the pressure changes in the external sphincter zone were caused predominantly by the concurrent changes produced in the detrusor and/or the smooth muscle components of the proximal urethra and of the external sphincter zone.