Biogenic amines and β-endorphin responses in the rat vas deferens

1. 1. Recent studies have demonstrated that activation of opioid peptide receptor by β-endorphin results in a change of bioamines in peripheral tissues. 2. 2. The present results could be interpreted assuming that the action of β-endorphin, on the smooth muscle of the isolated rat vas deferens, is independent of catecholaminergic, cholinergic and tryptaminergic neurotransmission. 3. 3. There is evidence that it is through a specific opioid 'ε{lunate}-receptor' which have been shown a high degree of affinity for β-endorphin.