Effect of glyceryl trinitrate on antral motility and symptoms in patients with functional dyspepsia. 
Nitric oxide (NO) is considered to be an important physiologic non-adrenergic, non-cholinergic vagal transmitter in the neural regulation of gastric adaptive relaxation, which accommodates the gastric fundus to ingested food.  Ten consecutive patients with functional dyspepsia (FD) and erosive prepyloric changes were studied twice on separate days, once without drug administration and once after intake of one tablet of glyceryl trinitrate (GTN), 2.6 mg, 2 h before ingestion of 500 ml meat soup.  Width of antral area, amplitude (maximal area reduction as fraction of relaxed area), and frequency of antral contractions were measured ultrasonographically in standardized sections.  Postprandial abdominal discomfort was scored.  Without GTN, postprandial antral area and symptom scores were positively correlated (r = 0.64, p = 0.05).  After administration of GTN, antral area both fasting and 10 min postprandially was reduced (p = 0.02 and p = 0.01, respectively), whereas amplitude and motility index of antral contractions tended to increase (p = 0.07 and p = 0.09, respectively).  Abdominal discomfort was not significantly reduced by GTN (p = 0.13).  The results suggest a relationship between postprandial antral distension and discomfort.  Moreover, GTN (by generation of NO) reduced abnormal antral filling in patients with FD.