Fig. 1.

The isolated bladder-urethra preparation. The double-lumen urethral catheter consisted of external PE-160 tubing for urethral perfusion and internal PE-50 tubing for recording urethral perfusion pressure (UPP). A cone-shaped plug fashioned from a 200-μl Eppendorf pipette tip and serving as the tip of the double-lumen urethral catheter was seated in the bladder neck to separate the urethra from the bladder functionally. Separate PE-50 tubing was used for bladder filling and pressure recording.