Interaction of glucagon and pentagastrin on pepsin secretion in healthy subjects

The effect of pentagastrin in step-wise increasing doses of 0 . 02, 2 . 0 and 20 nmol/kg/h (0 . 01, 1 . 0, and 10 . 0 micrograms/kg/h) on pepsin and acid secretion was studied in seven healthy subjects. The study was repeated on another day during infusion of glucagon in a dose of 103 pmol/kg/h (0 . 36 micrograms/kg/h) which results in plasma-glucagon concentrations comparable with those seen after a protein-rich meal. Pepsin output was maximal after 0 . 2 nmol/kg/h (0 . 1 microgram/kg/h) of pentagastrin and 20 nmol/kg/h (10 micrograms/kg/h) resulted in a marked decrease. The dose of pentagastrin required for half-maximal pepsin output was less than 0 . 1 nmol/kg/h (0 . 05 micrograms/kg/h). When the study was repeated during infusion of glucagon, the dose-response curve was shifted to the right. The highest pepsin output was obtained with 20 nmol/kg/h (10 micrograms/kg/h) of pentagastrin and D50 increased to well over 1 microgram/kg/h. The dose of pentagastrin required for half-maximal acid secretion was about 0 . 3 nmol/kg/h (0 . 15 micrograms/kg/h) indicating that the sensitivity of the chief cells to pentagastrin is more than three times that of the parietal cells.