Endorphins--a role in lower urinary tract function? The effect of opioid blockade on the detrusor and urethral sphincter mechanisms.

A single blind trial of the effect of opioid blockade on lower urinary tract function, assessed urodynamically, is reported. Twenty patients (10 male, 10 female) were studied by filling and voiding cystometry and urethral pressure profilometry before and after the administration of a potent opioid antagonist, naloxone. A significant rise in subtracted detrusor pressure was demonstrated throughout bladder filling. Cystometric bladder capacity was reduced at both first and urgent desire to micturate. Significant reduction of the urethral closure pressure was also seen. These effects represent evidence of an endogenous opioid dependent element in the control of lower urinary tract function.