Gastric histamine release during insulin and pentagastrin infusion in patients with duodenal ulcer

Thirteen patients with proven duodenal ulcer were studied by a combined insulin/pentagastrin gastric secretion test. Acid output, gastric histamine output, and plasma histamine levels were measured. There were no significant changes in gastric or plasma histamine levels during insulin-induced acid secretion (median basal 0.62 nmol 10 min-1; median highest fraction 0.89; median basal plasma 4.87 nmol 1-1; median highest plasma 6.89). After pentagastrin infusion there was an immediate increase in gastric histamine to a peak (median 1.62 nmol 10 min-1 p less than 0.01) followed by a fall and then a second peak (median 3.18 p less than 0.002). The biphasic nature of the gastric histamine release is unexplained. The occurrence of acid secretion without histamine release during insulin infusion suggests that the changes induced by pentagastrin are not simply a passive "washout" of histamine during acid secretion. The lack of histamine release during insulin infusion is not compatible with the theory that histamine is the common final transmitter to the parietal cell.