PURPOSE: The present study was undertaken to compare the function of the urinary bladder, reflex changes of the urinary bladder, and bladder outlet, during micturition between mature male and female rats. MATERIALS AND METHODS: Mature male(n=6) and female(n=6) Sprague-Dawley rats weighing 250 to 300gm were used. After each rat was anesthetized with urethane(1g/kga simultaneous recording of the intravesical pressure and voided urinary volume during micturition were recorded. And then, the urethra was ligated placing 4-0 silk tie just distal to the bladder neck. Isovolumetric bladder contractions and urethral pressure were recorded independently. RESULTS: The voided volume and intravesical pressure during micturltion showed no significant differences between mature fema1e and male rats. During reflex bladder contraction, isovolumetric bladder contractions and urethral pressure also showed no significant differences between mature female and male rats. Administration of N-nitro-L-arginine(L-NOARG, 15mg/kg), a nitric oxide synthase inhibitor, intravenously in female rats, reversibly decreased the magnitude(42.5%, p<0.05) and duration(35.4%, p<0.05) of reflex urethral relaxation. There was no effect on reflex urethral relaxation in male rats. Administration of L-NOARG 20mg/kgintravenously in male rats reversibly decreased the magnitude(49.8%, p<0.05) and duration(38.7%, p<0.05) of reflex urethral relaxation. CONCLUSIONS: From the results, it appears that the function of the urinary bladder and the reflex change of the urinary bladder and bladder outlet during micturition showed no significant difference between male and female rats of similar weight. Howerever, the dosage of L-NOARG showed difference of the decreasing level of the magnitude and duration of the urethral relaxation.
Animals ; Female* ; Humans ; Male* ; Neck ; Nitric Oxide Synthase* ; Nitric Oxide* ; Rats* ; Rats, Sprague-Dawley ; Reflex ; Relaxation ; Silk ; Urethra ; Urinary Bladder* ; Urination