Spasmolytic effects of isocorydine on isolated vascular strips

d-Isocorydine (Isoc) is an alkaloid isolated from. It is similar to papaverine (Pap) in structure. Comparing with Pap, the spasmolytic effects of Isoc on the strips of aorta, portal vein and coronary artery have been studied. 1. Spiral strips of rabbit aorta. Noradrenaline (NA) 0.1μg/ml produced a strong contraction, antagonized by Isoc. Papaverine (Pap) produced an antagonism similar to that by Isoc. ID: Isoc 56±28μg/ml, Pap 63±31μg/ml (P>0.5). 2. Longitudinal strips of rabbit portal vein. NA 1μg/ml produced consistent contractions which were inhibited by both Isoc and Pap. ID: Isoc 25±11μg/ml, Pap 20±9μg/ml (P>0.5). 3. Spiral strips of bovine coronary artery. Isoc 30μg/ml caused a striking relaxation of the strips made contracted with K 40 mM. This relaxant effect was similar to that of Pap 30μg/ml. These results suggest that Isoc is a nonspecific vasodilator.