COMPARATIVE-STUDIES ON URETHRAL FUNCTION

Urethral pressure profiles (in vivo), opening pressures, and flow rate s at opening pressure (in vitro) were determined for female, male, pre gnant, ovariectomized (OVX), OVX and then estrogen-treated, and OVX an d then progesterone-treated rabbits. Using the isolated whole-urethra preparation, we determined the opening pressures and flow rates as wel l as the effects of 250 mu M phenylephrine, 250 mu M bethanechol, and 120 mM KCl on the urethral opening pressure and flow rate. The results demonstrated that (1) the urethral pressure profiles were similar for male and female rabbits, (2) ovariectomy and pregnancy decreased the urethral pressure profiles, (3) estrogen therapy partially reversed th e effect of ovariectomy on the urethra, and (4) progesterone therapy h ad little effect on the urethral pressure profile. With regard to open ing pressure and flow, (1) flow at opening pressure was lower in the m ale than in the female; (2) the opening pressure was increased by ovar iectomy; (3) phenylephrine and KCl stimulated a greater response in th e male than in the female, whereas the response to bethanechol was sig nificantly lower in the male than in the female; (4) the male had the greatest resistance to flow among all the groups; and (5) ovariectomy increased the resistance to flow and estrogen treatment reversed the e ffect of ovariectomy. In conclusion, ovariectomy had significant effec ts on urethral function that were reversed by estrogen therapy but not by progesterone therapy.