Effect of L-arginine on lower oesophageal sphincter motility in man

Objective inhibitory responses of the lower oesophageal sphincter (LOS) are mediated via an L-arginine/nitric oxide (NO) pathway, L-arginine is known as the precursor of NO. We have studied the effect of intravenous L-arginin e on LOS motility in man. Design Twelve healthy subjects participated in a double-blind, placebo-cont rolled randomized study. Methods We investigated the effect of continuous infusion of L-arginine (50 0 mg/kg body weight/120 min) in six subjects under fasting conditions. Six other subjects were studied under postprandial conditions. LOS pressure (LO SP), swallow-induced LOS relaxations and transient lower oesophageal sphinc ter relaxations (TLOSR) were measured with sleeve manometry combined with p H metry. The meal consisted of a carbohydrate-high fat meal, Blood samples were taken before and after administration of L-arginine or saline to deter mine plasma levels of amino acids, cholecystokinin and gastrin, Results Plasma levels of arginine and citrulline significantly(P < 0.05) in creased during L-arginine infusion, L-arginine did not affect plasma hormon e levels. Under fasting conditions, LOSP and TLOSR were not influenced by L -arginine. Ingestion of the carbohydrate-high fat meal significantly decrea sed LOSP, L-arginine did not significantly influence TLOSR frequency, eithe r under fasting conditions or postprandially, Conclusions These results suggest that in humans under fasting or postprand ial conditions intravenous infusion of L-arginine does not influence LOS mo tility, (C) 2000 Lippincott Williams & Wilkins.