An alpha 1-adrenoceptor-sensitive mechanism is responsible for the adrenergic inhibition of insulin secretion in the pig pancreas.

The alpha-adrenoceptor subtype mediating inhibition of insulin secretion in the pig was examined in an isolated pancreas preparation perfused with 5 mM glucose. It was found that noradrenaline and the alpha 1-adrenoceptor agonist phenylephrine, but not the alpha 2-adrenoceptor agonist UK 14,304, inhibited insulin secretion. The effect of noradrenaline was abolished by the alpha 1-adrenoceptor antagonist prazosin but was not affected by the alpha 2-adrenoceptor antagonist idazoxan. The inhibitory effect of phenylephrine was also inhibited by prazosin. Thus, in the pig, the alpha-adrenoceptor subtype inhibiting insulin secretion is of the alpha 1-type, which is different from the subtype involved in other species.