The effect of alpha-adrenoceptor stimulation and blockade on the static urethral sphincter function in healthy females.

The influence of noradrenaline and prazosin on the urethral closure function was evaluated in 10 healthy female volunteers. Measurements of pressure at varying cross sectional areas were carried out at the bladder neck, in the high pressure zone, and in the distal urethra. Prazosin reduced the static pressure, predominantly in the midportion of the urethra, whereas noradrenaline caused no significant pressure change. The urethral resistance to dilatation and the hysteresis were unaffected by the two agents. It is suggested that the response to prazosin is related to decreased activity of the urethral smooth as well as of the striated muscles, the latter as a result of a reduced somatomotor output from the central nervous system.