Low vagal tone and antral dysmotility in patients with functional dyspepsia.

Effects of acute mental stress on gastric antral motility were investigated in 23 healthy persons and 25 patients with functional dyspepsia (FD). Real-time ultrasonography of gastric antrum was recorded, after ingestion of 500 ml meat soup, during a 4-min resting period, 2.5 min of mental stress, and a 4-min recovery period. Amplitude of antral contractions was scored as a fraction of relaxed area. Motility-index was calculated as the amplitude multiplied by frequency. Measurement of skin conductance reflected sympathetic tone, and respiratory sinus arrhythmia (RSA) was calculated to index vagal tone. Antral motility was reduced by mental stress in the healthy persons, but not in FD patients. Group differences were significant for amplitude (p < 0.002) and motility-index scores (p < 0.02). Sympathetic tone increased during stress in both groups. Vagal tone was lower in the FD patients than in the healthy controls (p < 0.001). The lack of stress-related reduction of motility among patients with FD may, therefore, be a consequence of poor vagal tone.