Perception of phasic tension changes in the proximal stomach in man

Abstract

Distension protocols of the proximal stomach in volunteers elicit symptoms resembling those observed postprandially in functional dyspepsia patients. There is increasing evidence that fundic tension more than fundic elongation determines the intensity of those symptoms. In distension studies, there is a simultaneous activation of tension and elongation receptors. When phasic contractions occur on a fixed volume, phasic tension changes are generated. Erythromycin (Ery) enhances fasting gastric fundus tone and phasic fundic contractions in man (Bruley des Varannes, 1995). Aim: To study the perception of spontaneous and erythrnmycin induced phasic changes in fundic wall tension in healthy volunteers. Methods: In 24 healthy volunteers (8 women, mean age 24.0 + 2.0 y) a barostat balloon was placed in the stomach after an overnight fast. Simultaneously stationary antro-duodenal manometry was performed. The correct position of both probes was checked fluoroscnpically. After an accommodation period of 20 min graded isnvolumetric distentions were applied (100 ml increments during 2 rain). Perception was noted using a validated score (0-6) at each distension step to determine the threshold for sensation. After a 20 minute accommodation period, the balloon was inflated with a fixed volume just below the volume necessary to induce the first perception during 10 minutes. The volunteers were asked to indicate a perception score, at least every 30 seconds or sooner if they noticed any change in perception, on a keypad connected to the recording computer. In this isovolumetric mode, phasic tension rises are recognized as pressure peaks. Tracings were visually analyzed. An increase of intra-balloon pressure of 5 mmHg above the baseline was considered as a phasic contraction. If this increase of pressure was followed within 10 seconds with an increase in perception score, contraction was considered as recognized. Twenty minutes later, 200 mg of Ery was given IV over 20 rain. After 10 minutes the balloon was again inflated at the same volume. Results (mean -+ SEM) were compared using paired t test. Results: Before Ery 48.4 + 4.2% of phasic fundic contractions were recognized. Only 48.5% of these fundic contractions were followed by propagated antral contractions. The percentage recognized contractions was similar whether the fundic contraction was followed by an antral contraction or not. During Ery the recognition of phasic contractions rose to 59.8 + 3.1% (p=0.05). Conclusions: In healthy volunteers, phasic fundic tension changes can be generated and perceived. Increasing the intensity of those changes with Ery sensitizes the recognition scores. These findings provide further evidence that fundic tension receptor activation causes epigastric symptoms.