Inhibitory effect of lomerizine, a prophylactic drug for migraines, on serotonin-induced contraction of the basilar artery.

We examined the effects of lomerizine on serotonin (5-hydroxytryptamine, 5-HT)-induced contraction of the basilar artery and compared them with those of nifedipine. Although both lomerizine and nifedipine completely blocked K(+)-induced vasoconstriction, 5-HT-induced vasoconstriction was more strongly inhibited by lomerizine than nifedipine. A 5-HT(2A) antagonist inhibited the 5-HT-induced vasoconstriction, but a 5-HT(1B) antagonist did not. Lomerizine, but not nifedipine, suppressed 5-HT-induced Ca(2+) release in 5-HT(2A)-expressing HEK293 cells. Moreover, neither antagonist affected ATP-induced Ca(2+) release. These results suggest that lomerizine may inhibit not only voltage-dependent Ca(2+) channels but also 5-HT(2A) receptors and so inhibit 5-HT-induced contraction in the basilar artery.