THE EFFECT OF ISCHEMIA AND REPERFUSION INJURY ON URETHRAL CLOSURE PRESSURE IN THE RABBIT

B. Hines, MD, B. Hampton, MD, S. Smillen, MD, R. Bercik, R. Porges, MD

   Objective: The purpose of this study was to examine the effect of ischemia and reperfusion injury on urethral closure pressure.

   Materials and Methods: Ten white New Zealand female 4 Kg rabbits were used. Catheterization and urethral pressure measurements were made with an 8 F Lumax catheter placed via a puncture cystotomy into the urethra. Succinylcholine was used to paralyze skeletal muscle and the aorta was cross clamped to induce ischemia. The students t-test was used to analyze all continuous variables.

   Results: The contributions of skeletal muscle, smooth muscle/connective tissue, and vascular pressure in generating urethral closure pressure are respectively 20%, 27% and 53%. After a 3 hour ischemic insult, when measured 3 days later, there was a significant decrease in total urethral closure pressure from 42.3 mmH2O to 37.3 mmH2O p=0.04. There was a significant decrease in the smooth muscle/connective tissue component from 23.3 mmH20 to 19 mmH20 p=0.04. The decrease in smooth muscle/connective tissue accounted for 80% of the total decrease.

   Conclusion: This pilot study suggest that injury to the smooth muscle in the urethra occurs following a 3 hour ischemic insult.