Local Effect of Psychotherapeutic Agents on Rabbit Penile Corpus Cavernosum

Park, Hae Young; Woo, Young Nam

Abstract

The mechanism of erectile dysfunction associated with psychotherapeutic medication is not well defined. To determine whether psychotherapeutic drugs have a direct effect on penile cavernosal smooth muscle, the activity of 4 drugs from 4 major classes of psychotherapeutic agents, chlorpromazine, thioridazine, haloperidol and amitriptyline, was examined in vitro on isolated rabbit corpus cavernosum. Strips of corpus cavernosum were mounted in organ baths for isometric tension studies. The effect of the drugs on resting tension, their relaxant effect on norepinephrine (NE) precontracted tissue, and their effect on electrical field stimulated (EFS) relaxation of NE precontracted tissue were determined. Incubation with any of the drugs did not affect resting tension compared to a control. All drugs produced a dose-dependent relaxation in NE precontracted tissue which were significantly greater than the water treated control (p<0.0001). None of the drugs inhibited EFS relaxation. These result show that these classes of drugs do not affect the basal tone of the corpus cavernosum. All have intrinsic relaxant properties and none interfere with neurally stimulated relaxation. This study suggests that drugs from these 4 major classes of psychotherapeutic agents do not adversely affect penile cavernosal smooth muscle relaxation at the level of the penis and its associated neural elements. It may be inferred that reports of impotence in patients treated with these classes of drugs more likely reflect a central or primary psychopathologic process rather than a local corpus cavernosum effect.