Effects of sildenafil on esophageal motility of normal subjects

Sildenafil shows an intense and prolonged inhibitory effect on the smooth m uscle cells of corpus cavernosum arterioles by blocking phosphodiesterase t ype 5 that inactivates the nitric oxide-stimulated cyclic guanosine monopho sphate. We investigated if this inhibitory effect is also displayed on smoo th muscle cells of the esophagus. In 16 normal subjects (9 men and 7 women, mean age 34 years, range 22-56) esophageal motility was recorded by means of a low-compliance manometric system with side holes for the esophageal bo dy and a sleeve for the lower esophageal sphincter (LES). After a basal per iod of 60 min, a tablet of sildenafil 50-mg ground and dissolved in water w as infused in the stomach in eight subjects (group A.) and a placebo tablet in the other eight subjects (group B), randomly and in a double-blind mann er; the recording continued for another 60 min. LES tone and postdeglutitiv e residual pressure, as well as amplitude, propagation velocity, and onset latency of contractions were measured each minute, the values averaged ever y 5 min, and the mean of the entire basal and postinfusion periods was calc ulated. The postinfusion values were compared with the basal values in each group and with the corresponding values of the other groups. The percent v ariations of postinfusion values with respect to basal values were also com pared. Sildenafil induced a statistically significant decrease of LES tone, residual pressure, wave amplitude, and propagation velocity and a signific ant increase of onset latency of pressure waves in comparison with the valu es of the basal period and placebo. The inhibitory effect reached its maxim um 10-15 min after the infusion and lasted about 1 hr. In conclusion, silde nafil markedly inhibits the motor activity of the esophageal musculature by decreasing LES pressure, wave amplitude, and propagation velocity and incr easing the onset latency of pressure waves.