metiamide and phenethylamine

beta-Phenylethylamine (PEA) produced a contraction of the guinea-pig isolated lung parenchymal strip and bronchoconstriction of perfused lungs. Reserpine pretreatment had little effect on these responses indicating a substantial direct effect. Phentolamine (10(-6) and 10(-5) M) had minimal effect on PEA in the lung strip compared with that on noradrenaline, eliminating involvement of alpha-adrenoceptors. PEA was unaffected by atropine (10(-7)M) or a mepyramine (10(-7)M); metiamide (10(-4)M) mixture. The contraction was not therefore mediated via muscarinic or histaminergic receptors. 5-HT and dopamine receptors were also discounted. Possible stimulation of a phenylethylaminergic receptor and its relevance to bronchial asthma is discussed.

Topics: Animals; Atropine; Bronchi; Carbachol; Dopamine; Drug Interactions; Female; Guinea Pigs; Histamine; Lung; Male; Methysergide; Metiamide; Muscle Contraction; Norepinephrine; Phenethylamines; Phentolamine; Propranolol; Pyrilamine; Serotonin