Effect of adrenergic blockade on gastric secretion altered by catecholamines in rats.

The effect of adrenergic blockade on gastric secretion altered by catecholamines was studied for 4 hr after injection in rats with chronic gastric fistulas. The alpha-adrenergic blockers phenoxybenzamine and phentolamine significantly inhibited the basal secretion of HCl and pepsin. Blockade of the beta-adrenergic receptors with propranolol did not change this secretion. Practolol in small doses slightly increased and in larger doses inhibited HCl out-put. Of the catecholamines, adrenaline and dopamine most markedly reduced HCl and pepsin secretion, while noradrenaline and isoprenaline had a weaker effect. Neither alpha- nor beta-adrenergic blockers prevented the inhibitory action of the catecholamines employed, but intensified the depression of the gastric secretion provoked by them. Adrenergic blockers inhibited secretion after catecholamines as well as basal secretion. This indicates that these two antagonistic groups of compounds act independently on the mechanism controlling gastric secretion. It is unlikely that this takes place indirectly through changes in the blood supply of the gastric mucosa.