Effects of l-stepholidine on isolated rabbit basilar artery, mesenteric artery, and thoracic aorta

l-Stepholidine (SPD) has been shown to be effective in treating migraine, but its mechanism is not clear. So the effects of SPD on isolated rabbit basilar artery (BA), mesenteric artery (MA) and thoracic aorta (TA) were studied. The contractions of BA and MA were induced by KCl (10-160 mmol.L-1) and the contraction of TA was caused by 5-HT (0.1-100 mumol.L-1). Ketanserin was used as reference. SPD (0.1-0.2 mmol.L-1) relaxed the contractions of BA and MA induced by KCl in a noncompetitive manner with pD'2 3.4 +/- 0.3 and 4.0 +/- 0.3, respectively. SPD had no selectivity in BA and MA. SPD also inhibited the contraction of TA induced by 5-HT with pA2 9.7 +/- 2.0 and pD'2 5.4 +/- 0.6, which showed a dual of both competitive and noncompetitive antagonisms. These results suggested that SPD had a blockade effect on the calcium channel and 5-HT2 receptors.