Effects of vasoactive intestinal polypeptide (VIP) on lower esophageal sphincter in awake baboons: comparison with glucagon and secretin.

The effects of vasoactive intestinal polypeptide (VIP), glucagon, and secretin on lower esophageal sphincter pressure were investigated in awake baboons. The three hormones were compared with respect to effect on (1) resting lower esophageal sphincter pressure and (2) maximal stimulatory response to pentagastrin. VIP was shown to reduce resting and pentagastrin-stimulated lower esophageal sphincter pressure with significantly greater potency than either secretin or glucagon. For reduction of resting lower esophageal sphincter pressure, the potency ratio of VIP to secretin was 16:1 and of VIP to glucagon was 32:1 (P less than 0.05). For inhibition of pentagastrin-stimulated sphincter pressure, the potency ratio of VIP to secretin was 32:1 and of VIP to glucagon was 64:1 (P less than 0.02). This demonstration of significantly increased potency of VIP over known inhibitory hormones strengthens the suggestion that VIP may have a physiologic role in the control of lower esophageal sphincter function.