New pharmacological aspects of the bronchodilating activity of procaterol

The selectivity of procaterol for beta 2-adrenoceptors vs beta 1-adrenoceptors in animals has been already described. In these studies the ability of procaterol to protect guinea-pig against bronchoconstriction induced by various spasmogens such as histamine, LTC4 and acetylcholine is demonstrated. The results obtained both in anaesthetized animals and in perfused lungs clearly show that procaterol antagonizes not only the direct effect of the bronchoconstrictors quoted above but also their ability to activate arachidonic acid metabolism and to augment the generation of TXA2. Procaterol (0, 3-3 micrograms/Kg i.v.) is more potent than salbutamol in protecting passively sensitized guinea-pig from massive bronchoconstriction following antigen challenge: a phenomenon which is paralleled by an increment of the circulating TXA2. The possibility that the adenylate-cyclase-stimulating properties of procaterol may explain its antiasthmatic activity is discussed.