Involvement of nitric oxide in human transient lower esophageal sphincter relaxations and esophageal primary peristalsis.

BACKGROUND & AIMS: Nitric oxide (NO) is well accepted as an inhibitory neurotransmitter in the gastrointestinal tract; however, its role in the triggering of transient lower esophageal sphincter relaxations (TLESRs) in humans remains to be determined. Therefore, the effect of NG-monomethyl-L-arginine (L-NMMA), a specific NO synthase blocker, on gastric distention-induced TLESRs was investigated.

METHODS

Esophageal manometry was performed using a perfused sleeve assembly. The effect of L-NMMA was evaluated on water swallow-evoked primary peristalsis (n = 8; single-blind, placebo-controlled) and on the rate of TLESRs during gastric distention (n = 8; double-blind, placebo-controlled).

RESULTS

L-NMMA increased the amplitude of peristaltic pressure waves in the distal esophagus and increased peristaltic velocity in the proximal esophagus. In contrast, L-NMMA had no effect on basal lower esophageal sphincter pressure, nadir pressure, duration, and area under the curve of lower esophageal sphincter relaxation. L-NMMA significantly inhibited the increase in TLESRs during gastric distention. L-NMMA also increased the intraballoon pressure during distention.

CONCLUSIONS

NO is one of the neurotransmitters involved in the reflex arc mediating the triggering of TLESRs. NO is involved in the timing of human esophageal peristalsis and may exert a tonic inhibition on the proximal stomach.