The classification of adrenoceptors and their effects on gastric acid secretion.

The actions of adrenoceptor agonists and antagonists are by no means agreed even though experiments with adrenal medulla extract date back to the beginning of the century. This review will consider the work of my own group and that of others in an attempt to classify the adrenoceptors which modulate gastric acid secretion. There are a number of factors to consider. Species differences are important and particular attention will be given to results from rat, dog and human. The secretagogue used is also important because the effect of adrenoceptor agonists and antagonists can be modified by the choice of histamine, muscarinic agonist, (penta) gastrin or food. Other factors include the gastric model used and the presence or absence of anaesthesia. The broad conclusions are that both alpha- and beta-adrenoceptors can inhibit gastric acid secretion. Both beta 1- and beta 2-adrenoceptors mediate inhibition of pentagastrin-induced secretion while alpha-adrenoceptors are important in the reduction of histamine-induced gastric acid secretion.