EFFECTS OF NITROGLYCERIN ON LIQUID GASTRIC-EMPTYING AND ANTROPYLORODUODENAL MOTILITY

The effects of the nitric oxide donor nitroglycerin on gastric emptyin g and antropyloroduodenal motility were evaluated in nine healthy male subjects (ages 19-36 yr). Antropyloroduodenal pressures were recorded with a manometric assembly that had nine side holes spanning the antr um and proximal duodenum and a pyloric sleeve sensor; gastric emptying was quantified scintigraphically. In each subject, the emptying of 30 0 ml of 25% glucose labeled with Tc-99m was assessed on two separate d ays during intravenous infusion of either nitroglycerin (5 mu g/min in 5% dextrose) or 5% dextrose (control). Studies were performed with th e subject in the supine position; blood pressure and heart rate were m onitored. Nitroglycerin had no significant effect on blood pressure or heart rate. Nitroglycerin slowed gastric emptying (P < 0.02), and thi s was associated with greater retention of the drink in the proximal s tomach (P < 0.05). In both nitroglycerin and control studies, ingestio n of the drink was associated with an increase in the number of isolat ed pyloric pressure waves (P < 0.05) and antral pressure wave sequence s (P < 0.05). Nitroglycerin reduced the number of isolated pyloric pre ssure waves (P < 0.05), basal pyloric pressure (P < 0.05), and the num ber of antral pressure wave sequences (P < 0.05), but not the total nu mber of antral pressure waves. The rate of gastric emptying and the nu mber of isolated pyloric pressure waves were inversely related during control (P = 0.03) and nitroglycerin (P < 0.05) infusions. We conclude that in normal subjects, 1) gastric emptying of 300 ml of 25% glucose is inversely related to the frequency of phasic pyloric pressure wave s, and 2) nitroglycerin in a dose of 5 mu g/min inhibits pyloric motil ity, alters the organization but not the number of antral pressure wav es, and slows gastric emptying and intragastric distribution of 25% gl ucose.