Effect of Sildenafil on Esophageal Motor Function in Healthy Volunteers

Seo, Won Tae; Park, Hyo Jin; Kim, Jung Hwan; Ji, Sang Won; Lee, Sang In; Park, In Suh

Abstract

BACKGROUND/AIM: Nitric oxide (NO), the nonadrenergic, noncholinergic inhibitory neurotransmitter, plays a role in controlling esophageal motor function by causing guanosine 3', 5'-cyclic monophosphate (cGMP) accumulation in circular smooth muscle of the esophagus and lower esophageal sphincter (LES). Increase in the intracellular concentration of cGMP as a second messenger produces relaxation of smooth muscle. It is metabolized by phosphodiesterase (PDE). Sildenafil, a drug used to improve the functional impotence, shows an inhibitory effect on the smooth muscle cells of the human corpus cavernosum by blocking type V PDE that destroys cGMP. The aim of this study was to investigate the effects of sildenafil on the esophageal motility.
METHODS
Eight male subjects without any evidence of esophageal motor dysfunction were enrolled in this study. On first day, 20 ml of distilled water (placebo) was infused into the stomach. On second day, 0.8 mg/kg of sildenafil powder dissolved in water was infused into the stomach. We measured the amplitude of esophageal body contractions and LES pressure at each day. In addition, plasma cGMP levels were assayed by ELISA method.
RESULTS
There were no significant differences in esophageal manometric findings in the placebo group, but significant decreases in LES pressure as well as amplitude of peristaltic contractions at smooth muscle portion of esophagus were noted in sildenafil group. Sildenafil showed its maximum effect in lowering LES pressure on 30 minutes after ingestion, and also in decreasing the amplitude of peristaltic contractions at smooth muscle portion of esophagus on 15 minutes after ingestion. There was no difference in the propagation velocity of peristalsis and plasma cGMP levels after sildenafil treatment.
CONCLUSION
Sildenafil showed inhibitory effects on smooth muscle of esophageal body and LES in human.