title: The inherent rhythmic contraction property of penile tissue in sexually active adult male rats and the effect of sildenafil citrate (Viagra): an in vitro pilot study.
abstract: Isolated human cavernosal muscles and those of various animals have extensively been studied for understanding the causes and treatment of erectile dysfunctions. Usually these tissues are first pretreated with suitable drugs, i.e. Noradrenaline (N-Adr), phenylephrine, carbacol, KCl and nicorandil etc. to induce resting tone or contractions in them, followed by the application of relaxing drugs like sildenafil. We undertook this project to show first of all that these penile tissues were capable of generating rhythmic contractions if properly treated with suitable drugs, either alone or in combination, and then to study the properties of these induced tensions and/or contractions. Attempt was also made to study the effects of sildenafil on various parameters of these contractions. Pretreatment of the tissues with atropine and N-Adr both initiated rhythmic contractions, the atropine effect being more potent (2-1/2 times larger) on the contraction rate while N-Adr effect being significantly higher on the resting tone. Atropine also increased the contraction rate and strength of contractions in the washed tissues or when it was applied in combination with N-Adr. Ach had no effect on the rate and strength of contractions in atropine treated tissues but it decreased contraction rat in washed tissues or when applied in combination with sildenafil. Sildenafil decreased the rate and strength of contractions in all the tissues pretreated with atropine or N-Adr or in the washed tissues. The effect of sildenafil was more potent on atropine treated tissues than those on N-Adr treated ones. Atropine, Acetylcholine (Ach) and sildenafil had no effect on the resting tone of the tissues while N-Adr significantly increased the resting tone in both the atropine treated and washed tissues.
authors.affiliation: Department of Physiology, Faculty of Medicine and Medical Sciences, Umm Al-Qura University, Makkah Almukarramah, Saudi Arabia.
authors.forename: Nabeeh I A
authors.initials: NI
authors.lastname: Rakkah