Perception of changes in wall tension of the proximal stomach in humans

Abstract

Background: Hypersensitivity to distension of the stomach is a frequent finding in functional dyspepsia. During gastric distension studies both wall tension and elongation are increased.

Aim: We wished to distinguish changes in wall tension from changes in elongation in the genesis of perception of mechanical stimuli originating from the proximal stomach in healthy subjects.

Subjects and methods: Twenty six volunteers were studied using gastric barostat and antroduodenal manometry. In 14 subjects, stepwise isobaric and isovolumetric distensions were performed before and during erythromycin infusion. In all volunteers, on a separate occasion, phasic contractions of the proximal stomach were detected as intraballoon pressure increases during fixed volume inflation. These contractions were matched with perception changes during two 10 minute periods, before and during administration of erythromycin.

Results: Erythromycin significantly lowered the perception and discomfort thresholds during stepwise gastric distension. During fixed volume inflation, erythromycin increased the number and amplitude of fundic contractions and enhanced their perception from 51.1 (7.4)% to 64.0 (4.7)%. The proportion of perception score increases coinciding with fundic contractions increased from 47.3 (0.7)% to 81.5 (0.5)%. The amplitude of correctly identified isolated fundic pressure waves was higher compared with non-identified waves.

Conclusions: These results support the hypothesis that changes in gastric wall tension may be involved in the genesis of symptoms originating from the stomach.

Figure 1

Schematic model of the proximal stomach wall with muscular component, in series tension receptor, and in parallel elongation receptor. The four panels represent the behaviour of the model in various experimental conditions. Top: Neutral condition; second panel: during distension both elongation and tension receptors are activated (Act). Muscular contraction status is unchanged; third panel: during relaxation, elongation but not tension receptors are activated. The muscular component is lengthened; bottom: during isometric contraction only tension receptors but not elongation receptors are activated. The muscular component is shortened. Inact, inactivated.

Figure 2

Influence of intravenous (IV) erythromycin on tone of the proximal stomach. Gastric tone is reflected by the volume of a barostat balloon in the proximal stomach. Intraballoon pressure is kept constant at a fixed pressure selected to obtain an initial volume of approximately 400 ml. Values are mean (SEM). Student's t test: **p<0.01 (n=14).

Figure 3

Influence of erythromycin 10 mg/min given intravenously on motor activity of the stomach and duodenum. Combined barostat of the proximal stomach and antroduodenal manometry in a healthy volunteer. The highest trace represents intraballoon volume. The second and third channels show antral pressure, and the four other channels duodenal pressure. Erythromycin induced enhancement of fundic tone (represented as a decrease in intraballoon volume) which preceded the appearance of antral phase III-like contractions.

Figure 4

Distension-perception relation during isovolumetric distensions of the proximal stomach. A barostat balloon placed in the proximal stomach is inflated stepwise with increasing volumes (step increment 100 ml, step duration two minutes). Perception of abdominal discomfort is recorded at the end of each distension step on a scale ranging from 0 to 6, before and during intravenous infusion of erythromycin. Erythromycin (10 mg/min) significantly enhanced perception of gastric distension. Values are mean (SEM) perception scores (area under the curve; p<0.01) (n=14).

Figure 5

Perception of phasic activity of the proximal stomach. Combined barostat of the proximal stomach and antroduodenal manometry in a healthy volunteer. The highest trace represents perception score. The second and third traces shows intraballoon pressure and volume, respectively. The six other traces represent antroduodenal manometry. This tracing illustrates fundic pressure waves propagated or not to the antrum. Some of the fundic pressure waves were identified by the volunteer.