The effects of isoprenaline and noradrenaline on pentagastrin-stimulated gastric acid secretion and mucosal blood flow in the dog.

1. Isoprenaline (0.02 to 2.0 mug kg(-1) min(-1)) inhibited gastric secretion in response to pentagastrin in both conscious and anaesthetized dogs and in response to feeding in conscious dogs.2. The inhibition was unaffected during cardiac beta-adrenoceptor blockade by propranolol.3. The inhibition was not due to decreased mucosal blood flow.4. This effect of isoprenaline is different from its effect on histamine-induced gastric secretion.5. Noradrenaline (0.05-2.0 mug kg(-1) min(-1)) also decreased gastric secretion but it was less effective than isoprenaline.6. The mechanism of action of noradrenaline is probably a decrease in mucosal blood flow.