Cholinergic stimulation augments maximal (penta) gastrin-stimulated acid secretion in man

Abstract

In the vascularly perfirsed isolated rat stomach, maximal histamine stimulated acid secretion is higher than maximal gastrin stimulated, and the former may be augmented by concomitant cholinergic stimulation. The purpose of the present study was to examine whether maximal pentagastrin stimulated acid secretion may be augmented by concomitant vagal stimulation in man. Eight students (one female, seven males) gave an informed written consent to participate in the study. Each subject was studied thrice after an overnight fast, and with an interval at least of one week. On the first day maximal pentagastrin stimulated acid secretion was assessed by giving pentagastrin at a dose of 0.1 ~tg/kg/min which previously has been shown to give maximal gastrin stimulated acid secretion. On day two, acid secretion was stimulated by insulin induced hypoglycemia applying glucose clamp technique establishing a blood glucose level of around 2.1 mmol/1 for a 30 min period. On day three, gastric acid secretion was simultaneously stimulated with pentagastrin and hypoglycemia. Insulin induced hypoglycemia was more short-lived than that stimulated by pentagastrin. Therefore maximal acid output (MAO) was higher when stimulated by pentagastrin than by insulin hypoglycemia. Peak acid output (PAO) was, however, closely similar. The combined stimulation induced an increase in PAO in all subjects when compared with that stimulated by pentagastrin or hypoglycemia alone. The augmentation of pentagastrin stimulated PAO when applying hypoglycemia simultaneously was from 5 to 50% with a median value around 20%. The present study shows that insulin induced hypoglycemia to stimulate the vagal nerves and thus gastric acid secretion, is a safe procedure when utilizing the glucose clamp technique. Moreover, pentagastrin stimulated acid secretion does not represent maximal gastric secretory capacity in man.