['In vitro, nitric oxide (NO) has been shown to be the neurotransmitter responsible for gastric relaxation. In vivo gastric relaxations can be controlled via reflex pathways originating in the duodenum. The aim of this study was to determine whether NO was involved in gastric relaxation in vivo in conscious dogs induced by intraduodenal administration of intralipid. Gastric tone was monitored with a flaccid bag introduced into the stomach via a gastric cannula and connected to a barostat. Intralipid administration into the duodenum caused a gastric relaxation (420 +/- 11 ml, n = 6) sensitive to inhibition by nitro-L-arginine (L-NNA) (5 mg kg-1 i.v.). This inhibitory effect of L-NNA was reversed by L-arginine (100 mg kg-1 i.v.).'] Is intralipid-induced gastric relaxation mediated via NO?