Abstract: AIM: To observed the effects of BWYJ (a naftopidil ramification) on intracellularlar free Ca²⁺ ([Ca²⁺]_i) in smooth cells (SMCs) in order to further explore its vasodilative mechanisms. METHODS: The [Ca²⁺] _i was determined with the Fura-2 /AM loaded SMCs in aorta of rabbit, and the effects of BWYJ on the elevation induced by NA, and high potassium and 5-HT were observe. RESULTS: In the Fura-2 /AM loaded SMCs, BWYJ had no effect on the resting [Ca²⁺] _i, but it reduced the increase of [Ca²⁺] _i induced by NA and 5- HT, and there was no influence on the increase of [Ca²⁺] _i induced by high potassium. CONCLUSION: The vasodilative mechanisms of BWYJ may be related to its inhibitive effects on the Ca²⁺-influx and Ca²⁺-release mediated by α₁- and 5-HT₂A receptors. It inhibits the release of intracellular calcium, and the result is it decrease the [Ca²⁺] _i in SMCs.

Key words: BWYJ, naftopidil, intracellularlar free Ca²⁺ ([Ca²⁺] i), noradrenaline, KCl, 5-HT