The nitric oxide synthase inhibitor, Ng-nitro-l-arginine-methyl-ester, attenuates the delay in gastric emptying induced by hyperglycaemia in healthy humans

Abstract The aim of this study was to determine whether the nitric oxide (NO) synthase inhibitor, N^g‐nitro‐l ‐arginine‐methyl‐ester (l ‐NAME), reverses the effects of acute hyperglycaemia on gastric emptying and antropyloroduodenal (APD) motility. The study had a four‐way randomized crossover (hyperglycaemia vs euglycaemia; l ‐NAME vs placebo) design in a clinical laboratory setting. Seven healthy volunteers [four males; age 30.3 ± 3.8 years; body mass index (BMI) 23.6 ± 1.2 kg m^?2] were the study subjects. After positioning a transnasal manometry catheter across the pylorus, the blood glucose concentration was maintained at either 15 or 5 mmol L^?1 using a glucose/insulin clamp. An intravenous infusion of l ‐NAME (180 μg kg^?1 h^?1) or placebo (0.9% saline) was commenced (T = ?30 min) and continued for 150 min. At T = ?2 min, subjects ingested a drink containing 50 g of glucose made up to 300 mL with water. Gastric emptying was measured using 3D ultrasound, and APD motility using manometry. Hyperglycaemia slowed gastric emptying (P < 0.05), and this effect was abolished by l ‐NAME. l ‐NAME had no effect on gastric emptying during euglycaemia. Hyperglycaemia suppressed fasting antral motility [motility index: 3.9 ± 0.8 (hyperglycaemia) vs 6.5 ± 0.6 (euglycaemia); P < 0.01]; l ‐NAME suppressed postprandial antral motility [motility index: 3.6 ± 0.2 (l ‐NAME) vs 5.1 ± 0.2 (placebo); P < 0.001]. Postprandial basal pyloric pressure was higher during hyperglycaemia (P < 0.001), and lower after administration of l ‐NAME (P < 0.001). Slowing of gastric emptying induced by hyperglycaemia is mediated by NO, and may involve the modulation of tonic pyloric activity.     

Measurements of gastric emptying of low- and high-nutrient liquids using 3D ultrasonography and scintigraphy in healthy subjects

Scintigraphy represents the 'gold standard' for the measurement of gastric emptying. Recent studies suggest that three-dimensional (3D) ultrasonography may allow a precise measure of gastric emptying, given the capacity for accurate volume calculations of the stomach. The aim of this study was to compare measurements of gastric emptying of both low- and high-nutrient drinks by 3D ultrasonography with scintigraphy. Ten healthy young subjects (6M, 4F, age 23.5 +/- 1.5 years) were studied on 2 days. Concurrent measurements of gastric emptying by scintigraphy and 3D ultrasonography were performed after ingestion of 500 mL beef soup (12 kcal) or 300 ml dextrose (25% w/v) (314 kcal) labelled with 20 MBq (99m)Tc-sulphur colloid. There was no significant difference between scintigraphic and ultrasonographic 50% emptying times (T50s) (soup: 27.7 +/- 4.8 min vs 23.8. +/- 4.8 min; dextrose: 122.2 +/- 13.3 min vs 131.9 +/- 10.2 min). There was a close correlation between scintigraphic and ultrasonographic T50s for both soup (r = 0.92, P = 0.0005) and dextrose (r = 0.88, P = 0.0007). For the T50s, the limits of agreement were -15.2 min and +8.1 min for the soup (mean difference -3.6 min) and -35.3 min and +47.6 min for dextrose (mean difference +6.2 min). 3D ultrasonography provides a valid measure of gastric emptying of liquid meals in healthy subjects.