Gastric emptying after truncal vagotomy and pyloroplasty

Gastric stasis in neuronal nitric oxide synthase-deficient knockout mice

BACKGROUND & AIMS

Nitric oxide (NO) is a major inhibitory neurotransmitter in the gut. This study aimed to identify the effect of chronic deprivation of NO derived from neuronal (nNOS) or endothelial (eNOS) nitric oxide synthase on gastric emptying.

METHODS

nNOS-deficient (knockout) mice were compared with wild-type mice for gastric size, fluoroscopic appearance after gavage of contrast, and histology of the pyloric sphincter. Wild-type mice treated with the NOS inhibitor N(omega)-nitro L-arginine (L-NA) and eNOS-deficient mice were also compared with wild-type and nNOS-deficient mice for liquid and solid gastric emptying.

RESULTS

nNOS-deficient mice showed gastric dilation. Fluoroscopy showed delayed gastric emptying of radiologic contrast. There was no marked localized hypertrophy or luminal narrowing at the pyloric sphincter by histology of relaxed wild-type, nNOS-deficient, and eNOS-deficient tissues. Gastric emptying of both solids (28% +/- 27%) and liquids (22% +/- 18%) was significantly delayed in nNOS-deficient mice compared with control wild-type mice (82% +/- 22% for solids; 48% +/- 17% for liquids). eNOS-deficient mice showed no significant difference from wild-type mice (74% +/- 28% for solids; 47% +/- 23% for liquids). Wild-type mice treated acutely with L-NA showed delay in emptying of solids (43% +/- 31%) but not liquids (39% +/- 15%).

CONCLUSIONS

Chronic depletion of NO from nNOS, but not eNOS, results in delayed gastric emptying of solids and liquids.

Effect of truncal vagotomy on gallbladder bile kinetics in conscious dogs

Previous studies on the effects of vagotomy on gallbladder (GB) motility have yielded conflicting results. The aim of this study was to evaluate the effects of vagotomy on GB motility and bile kinetics using a new method. Twelve dogs were divided into two groups of six (control and pyloroplasty) and, 4 weeks later, underwent truncal vagotomy. A catheter secured in the GB fundus was used to monitor GB volume. After injecting polyethylene glycol (PEG) into the GB, combined measurements of GB volume and PEG concentration enabled GB emptying and bile kinetics to be estimated. Seven and five of the 12 vagotomized dogs were classified as having large and normal fasting GB volumes, respectively. Postprandial GB emptying was impaired when the fasting GB volume was enlarged. In the fasting state, bile kinetics of vagotomized dogs were significantly smaller than the control values. The emptying ability of the GB of vagotomized dogs with large fasting GB volumes was reduced considerably both in the postprandial and the fasting states. Such retention of bile in the GB after vagotomy may facilitate cholesterol crystal nucleation and stone growth.

Muscarinic blockade inhibits gastric emptying of mixed-nutrient meal: effects of weight and gender

We compared the vagal contribution to gastric emptying in lean and obese subjects by monitoring gastric emptying of a meal during muscarinic blockade. Lean (n = 6) and obese subjects (n = 6) underwent two treatments: 1) saline infusion and 2) atropine infusion [0.4 mg/m2 bolus, 0.4 mg. (m2)-1. h-1] for 2 h, initiated 30 min before ingestion of a 600-kcal breakfast (64% carbohydrate, 23% fat, 13% protein) composed of orange juice (labeled with Indium-111), egg sandwich (labeled with Technetium-99m), cereal, milk, and banana. Anterior and posterior images were taken every 90 s for 90 min using a dual-headed camera. Atropine significantly delayed emptying of both solid (P < 0.007) and liquid (P < 0.002). Obese subjects exhibited a greater delay in liquid emptying during muscarinic blockade compared with lean subjects (P < 0.02). Female subjects exhibited a slower rate of gastric emptying and were less sensitive to atropine. These data suggest that obese subjects exhibit altered gastric cholinergic activity compared with lean subjects and that gender differences in gastric emptying rate may be due to differences in autonomic tone.

Gastric emptying of two radiolabelled antacids with simultaneous monitoring of gastric pH

The aim of this study was to assess the gastric emptying rate of two antacids using an scintigraphic technique and simultaneous monitoring of gastric pH in 16 healthy male volunteers. Ten ml of Talcid (hydrotalcite 1 g) and Maalox (Mg-Al-hydroxide), with a similar neutralization capacity, were labelled with technetium-99m using a pyrophosphate bridge. Labelled antacids were given on separate days (within 2 weeks), 1 h after a standard meal. Intragastric pH was measured for at least 4 h, using ambulatory pH-metry with a dual-crystant antimony catheter. Continuous monitoring was started 1 h prior to the meal (baseline) and lasted 3 h (post-prandial, post-antacid and final periods). The antacid capacity of labelled and unlabelled antacids was similar. The mean percentages of antacids retained in the stomach fitted a linear model. The mean half-emptying time of Talcid was 63.9 +/- 27.9 min, while that of Maalox was 57.3 +/- 23.9 min (P = NS). The recordings of gastric pH (mean values of pH for each period) showed a similar profile for both antacids. The mean pH (Maalox vs Talcid) was 1.69 vs 2.07 in the baseline period, 1.95 vs 1.93 in the post-prandial period, 1.79 vs 1.15 in the post-antacid period (P = NS) and 0.4 vs 0.52 in the final period (P < 0.05 vs prior periods). In conclusion, the gastric emptying of Talcid and Maalox was similar and pH profiles were parallel and remained unchanged for the two antacids within the first hour of intake. A significant decrease in pH was observed 1 h after intake of the antacids, suggesting a possible rebound effect.

Gastric emptying of two radiolabelled antacids

The rate of gastric emptying of two antacids, magaldrate and Maalox, was investigated using scintigraphy. Successful labelling of the antacids was carried out with 99mTc. The stability of the 99mTc-labelled antacids was satisfactory and there was no difference in antacid capacity between the labelled and unlabelled antacids. The studies were carried out on 15 healthy male volunteers. After an eight hour fast each subject ingested a standardised meal of 95.7 MJ (400 kcal). One hour later 10 ml of one of the two antacids previously labelled with 99mTc was administered. Serial detection by anterior and posterior projection of the amount of antacid retained in the stomach was performed to determine gastric emptying of antacid. One week later the study was repeated under the same conditions with the other antacid also labelled with 99mTc. The mean (SD) percentages of antacid retained in the stomach fit a linear model with a t1/2 of 86.6 (15.3) minutes for magaldrate and 52.3 (5.2) minutes for Maalox (p less than 0.01). When the mean percentages of retention at six time intervals were compared for both antacids, it was found that Maalox emptied much faster (p less than 0.01 at 15 and 30 minutes, p less than 0.02 at 45, 60, 75, and 90 minutes).

Gastroparesis after a presumed viral illness: clinical and laboratory features and natural history

Gastroparesis after a viral infection has rarely been reported. In this article, we describe the clinical features and long-term outcome of 7 patients who had gastroparesis after a presumed viral illness and who were identified in a retrospective review of 103 consecutive cases of gastroparesis seen at our institution from 1977 through 1988. The three male and four female patients with gastroparesis after a suspected viral illness were young (mean age, 26.9 years) and healthy before the onset of the illness, which manifested as low-grade fever, fatigue, and myalgia with or without diarrhea. A mean of 4.5 days after spontaneous resolution of the viral illness, persistent nausea, vomiting, and epigastric pain developed in these patients. In all seven patients, delayed emptying of the gastric contents was substantiated. Autonomic neuropathy was found in all three patients who underwent autonomic function tests. During a mean follow-up of 32.3 months, five of the seven patients had complete resolution of gastroparetic symptoms, and the other two had considerable improvement of their condition. We conclude that postviral gastroparesis is uncommon, is frequently associated with autonomic dysfunction, and is associated with an apparently excellent prognosis.

Effect of truncal vagotomy on cholecystokinin release, gallbladder contraction, and gallbladder sensitivity to cholecystokinin in humans

The present study was undertaken to investigate the gastric and intestinal phase of stimulation of postprandial gallbladder contraction and endogenous cholecystokinin secretion in patients with truncal vagotomy and pyloroplasty. Gallbladder emptying, measured by cholescintigraphy, and endogenous cholecystokinin secretion, measured by radioimmunoassay, were studied after both intragastric and intraduodenal administration of corn oil. In addition, the gallbladder responsiveness to cholecystokinin was investigated by infusion of stepwise increasing doses of exogenous cholecystokinin. In the 6 patients with truncal vagotomy, plasma CCK and gallbladder responses to intraduodenal fat were significantly delayed compared to normal subjects. In contrast, the onset of the plasma cholecystokinin increase and gallbladder emptying after intragastric fat was significantly earlier in the vagotomized patients compared with the normal subjects. In the normal subjects, plasma cholecystokinin and gallbladder responses to intragastric fat were significantly lower during the first 25 min after stimulation compared with the results after intraduodenal fat, whereas in the patients with truncal vagotomy and pyloroplasty, no differences in plasma cholecystokinin and gallbladder responses were found according to the site of fat stimulation. The gallbladder-emptying response to exogenous cholecystokinin increased significantly in patients who had undergone truncal vagotomy. It is concluded (a) that truncal vagotomy with pyloroplasty influences the timing but not the magnitude of fat-stimulated gallbladder contraction and endogenous cholecystokinin secretion; and (b) that the sensitivity of the gallbladder to endogenous and exogenous cholecystokinin is significantly increased in patients with truncal vagotomy.