Effects of vasoactive intestinal peptide on resting and pentagastrin-stimulated lower esophageal sphincter pressure.

Vasoactive intestinal peptide (VIP) administered as an intravenous infusion at different doses (0.8, 1.6, and 3.2 micrograms per kg per hr, respectively) inhibited dose-dependently the response of the lower esophageal sphincter to an intravenous injection of pentagastrin (0.6 microgram per kg) in 4 healthy volunteers. Inhibition ranged from about 20% (not significant) with the low dose to about 55% (P less than 0.05) with the high dose. On the other hand, the VIP doses employed did not substantially decrease basal lower esophageal sphincter pressure. Calculated on the basis of plasma levels of the respective peptides, the inhibitory effect of VIP was about one-third of that of secretin. Even at the smallest dose of VIP, plasma levels of radioimmunoassayable VIP (20 to 100 pmoles per liter) markedly exceeded those encountered normally (1 to 19 pmoles per liter). So, the data presented do not support the suggestion that normally circulating VIP essentially contributes to the physiological regulation of the lower esophageal sphincter pressure; they do not exclude, however, such a role for locally released VIP.