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.