Role of striated sphincter muscle in urethral closure under stress conditions: an experimental study.

The three-component mechanism for urethral closure under stress conditions is composed of urethral tension, passive pressure transmission and reflex pressure transmission. The reflex pressure transmission is regarded as a global result of the striated muscles of the urethra and the pelvic floor. In this experimental study, the question of what peak the reflex pressure reaches and which parts of the striated sphincter muscles produce the reflex pressure transmission is examined. The urodynamic and operative experiment was carried out on 12 female German shepherd mutts, whereby the passive and the reflex pressure transmissions were brought about by the Credé maneuver and by induced sneezing, respectively, in differentiated experimental phases. It was shown that the amount of reflex pressure transmission alone totals 89%, which is added onto the given urethral tension and passive pressure transmission. Furthermore, this animal experiment demonstrates that the reflex pressure transmission is created almost solely by the periurethral striated sphincter muscles, whereas the participation of the intraurethral striated sphincter muscles lies at a low 4%.