nitroarginine and Gastric-Dilatation

Impaired gastric accommodation and gastric dysrhythmia are common in gastroparesis and functional dyspepsia. Recent studies have shown that synchronized gastric electrical stimulation (SGES) accelerates gastric emptying and enhances antral contractions in dogs. The aim of this study was to investigate the effects and mechanism of SGES on gastric accommodation and slow waves impaired by vagotomy in dogs. Gastric tone, compliance, and accommodation as well as slow waves with and without SGES were assessed in seven female regular dogs and seven dogs with bilateral truncal vagotomy, chronically implanted with gastric serosal electrodes and a gastric cannula. We found that 1) vagotomy impaired gastric accommodation that was normalized by SGES. The postprandial increase in gastric volume was 283.5 +/- 50.6 ml in the controlled dogs, 155.2 +/- 49.2 ml in the vagotomized dogs, and 304.0 +/- 57.8 ml in the vagotomized dogs with SGES. The ameliorating effect of SGES was no longer observed after application of N(omega)-nitro-L-arginine (L-NNA); 2) vagotomy did not alter gastric compliance whereas SGES improved gastric compliance in the vagotomized dogs, and the improvement was also blocked by L-NNA; and 3) vagotomy impaired antral slow wave rhythmicity in both fasting and fed states. SGES at the proximal stomach enhanced the postprandial rhythmicity and amplitude (dominant power) of the gastric slow waves in the antrum. In conclusion, SGES with appropriate parameters restores gastric accommodation and improves gastric slow waves impaired by vagotomy. The improvement in gastric accommodation with SGES is mediated via the nitrergic pathway. Combined with previously reported findings (enhanced antral contractions and accelerated gastric emptying) and findings in this study (improved gastric accommodation and slow waves), SGES may be a viable therapy for gastroparesis.

Topics: Animals; Compliance; Disease Models, Animal; Dogs; Electric Stimulation Therapy; Enzyme Inhibitors; Fasting; Female; Gastric Dilatation; Gastric Emptying; Gastroparesis; Muscle Contraction; Nitrergic Neurons; Nitric Oxide Synthase; Nitroarginine; Periodicity; Postprandial Period; Stomach; Vagotomy

Pentagastrin enhanced the volume increase caused by isobaric gastric distension in conscious dogs. This effect could be abolished by inhibitors of acid secretion and mimicked by histamine. The increased compliance after pentagastrin was not affected by L-nitroarginine (L-NNA), a blocker of nitric oxide (NO) synthase. L-NNA itself reduced the volume increases caused by isobaric gastric distension. Intralipid administration into the duodenum led to a gastric relaxation sensitive to inhibition by L-NNA. The inhibitory effect of L-NNA was partially reversed by L-arginine. Pentagastrin induces a gastric relaxation via a mechanism that involves gastric secretion but not nitric oxide, whereas intraduodenal intralipid induces a gastric relaxation via a NO-dependent mechanism.

Topics: Animals; Arginine; Dogs; Fat Emulsions, Intravenous; Gastric Acid; Gastric Dilatation; Gastric Emptying; Nitric Oxide; Nitroarginine; Pentagastrin; Stomach