Adrenergic neuron blocking action of dehydrocorydaline isolated from Corydalis bulbosa

Dehydrocorydaline, an active principle of Corydalis bulbosa alkaloids, in concentrations of 10(-5) M to 5 x 10(-5)M inhibited relaxation and the concomitant release of (3H)-noradrenaline caused by 10(-4)M nicotine and electrical perivascular nerve stimulation in the taenia caecum of guinea pig. The same inhibitory effects were observed on contraction and release of (3H) noradrenaline in the sympathetic nerve-pulmonary artery preparation of rabbit. On the other hand, neither relaxation nor contraction caused by exogenously applied noradrenaline was affected. These results suggest that the inhibitory action of dehydrocorydaline on the relaxation or contraction, produced by nicotine and electrical nerve stimulation, is due to blockade of noradrenaline release from the adrenergic nerve terminals in both the taenia caecum and pulmonary artery. Participation of the adrenergic neuron blocking action of dehydrocorydaline in preventing experimental ulceration is discussed.