The relationship between blood gastrin levels and gastric secretion in conscious dogs

1. In conscious dogs with gastric fistulae and Heidenhain pouches, acid and pepsin secretion, immunoreactive plasma pancreatic polypeptide (PP) and gastrin were measured following intravenously administered pentagastrin, cholinomimetics, and intragastric administration of milk. 2. Pentagastrin did not raise endogenous plasma gastrin. There was a significant positive dose-response relationship between pentagastrin and acid and fistula pepsin secretions, but not between plasma gastrin of endogenous origin and gastric secretion. 3. Carbachol raised plasma gastrin immunoreactivity; but in no instance was there a significant relationship between gastric secretion and plasma gastrin immunoreactivity. Gastric acid secretion faded, but plasma gastrin concentrations did not. 4. PP plasma immunoreactivity was elevated by methacholine and carbachol. Its levels correlated significantly with gastric acid secretion. Pentagastrin did not raise PP and its levels did not, therefore, correlate with gastric acid secretion. 5. Intragastric milk raised plasma gastrin immunoreactivity, but the acid secretion per pg of plasma gastrin was much smaller than with the cholinomimetics. Ganglionic blocking agents depressed both plasma gastrin and acid and pepsin secretion. 6. The results suggest that cholinomimetics sensitize parietal cells to the stimulating action of gastrin.