Pyloric pressure response to insulin-induced hypoglycemia in humans

The pyloric pressure response to insulin-induced hypoglycemia was studied. Studies were performed in 102 experiments on 38 normal subjects. During insulin-induced hypoglycemia, pyloric pressure increased from 5.5 +/- 1.2 to 10.8 +/- 1.1 mmHg (P less than 0.02). This increase in pyloric pressure ws not due to a direct effect of insulin, duodenal acidification, or the release of corticosteroids or growth hormone. Glucagon doses of 2 and 5 micrograms . kg-1 . h-1 increased pyloric pressure from 4.7 +/- 1.1 to 6.7 +/- 0.5 mmHg (P less than 0.05) and from 4.7 +/- 1.1 to 8.5 +/- 1.1 mmHg (P less than 0.02), respectively. Pyloric pressures were increased to 10.8 +/- 0.9 (P less than 0.01) and 13.0 +/- 1.4 mmHg (P less than 0.01) at 0.1 and 0.2 micrograms . kg-1 . min-1 of epinephrine, respectively. Neither cholinergic blockade nor alpha-adrenergic blockade significantly affected the pyloric pressure response to insulin hypoglycemia. beta-Adrenergic blockade abolished the pyloric pressure responses to both insulin hypoglycemia and epinephrine. Neither beta- nor alpha-adrenergic stimulation altered the basal pyloric pressure. In contrast, the combination of isoproterenol and phenylephrine increased the pyloric pressure significantly from 4.2 +/- 0.8 to 12.0 +/- 1.7 mmHg ( P less than 0.01). These observations suggest that insulin hypoglycemia increases pyloric pressure by an adrenergic mechanism that requires stimulation of both alpha- and beta-receptors.