Changes in Lower Esophageal Sphincter Pressure During Insulin-Induced Hypoglycemia

Abstract

Lower esophageal sphincter (LES) pressure has recently been shown to increase following injection of submaximal doses of pentagastrin or after maneuvers designed to cause endogenous gastrin release. These observations suggested that changes in LES pressure might provide a means to evaluate endogenous gastrin activity in vivo. This study was undertaken to observe possible changes in LES pressure during vagal stimulation of acid secretion following hypoglycemia induced by intravenous injection of 0.2 U per kg of regular insulin. In a group of normal subjects a rapid decrease in LES pressure was consistently noted at the time of occurrence of hypoglycemic symptoms and resulting increased gastric acidity. In each subject the study was repeated on a subsequent day, but with constant neutralization of the stomach by instillation of 0.1 n NaHC03. Under these conditions, consistent increases in LES pressure occurred during the hypoglycemic reaction. Further studies in patients having previous vagotomy and pyloroplasty revealed increased LES pressure during hypoglycemia despite the absence of gastric acid production. No increase in LES pressure was seen during hypoglycemia in patients having vagotomy and subtotal gastrectomy. These results would seem to confirm in man the effect of hypoglycemia on gastrin which has previously been shown in dog preparations. During hypoglycemia gastrin is released from the antrum, but this effect is inhibited by the simultaneous acid secretion. Neutralization of gastric contents or absence of acid secretion during hypoglycemia prevents the inhibitory effect of acid on the antral mucosa. The results of these studies suggest that gastrin release during hypoglycemia in man is not dependent on the vagus nerve.