Stereoselectivity of butylidenephthalide on voltage-dependent calcium channels in guinea-pig isolated ileum

Wun-Chang Ko, Joen Rong Sheu, Yi Rong Leu, Shu-Huey Tzeng, Chi Ming Chen

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Abstract

Two geometric isomers, the Z- and the E- forms, can be separated from synthetic mixtures of butylide-nephthalide (Bdph). Z-Bdph (50-100 μM) non-competitively inhibited Ca2+-induced contractions in depolarized (K+, 60 mM) guinea-pig ileum longitudinal smooth muscle, with a pD2' value of 3.88 ± 0.20 (n = 5). However, E-Bdph (20-100 μM) competitively inhibited these contractions with a pA2 value of 4.56 ± 0.18 (n = 5) which was significantly (P <0.05) greater than the pD2' value of Z-Bdph. In contrast, the two isomers had no stereoselective inhibitory action on Ca2+ influx through pre- or post-junctional membranes of cholinergic nerve endings from which the transmitter acetylcholine is released or on Ca2+ release from intracellular stores. Therefore, the trans-Z and cis-E forms of Bdph might have geometric stereoselectivity for voltage-dependent calcium channels (VDC) in guinea-pig longitudinal smooth muscle. Both isomers might inhibit more selectively the contractile twitch responses evoked by electrical stimulation than by cumulative acetylcholine or carbachol-induced transient contractions in guinea-pig ileum longitudinal smooth muscle.

Original languageEnglish
Pages (from-to)1121-1125
Number of pages5
JournalJournal of Pharmacy and Pharmacology
Volume49
Issue number11
Publication statusPublished - Nov 1997

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ASJC Scopus subject areas

  • Pharmaceutical Science
  • Pharmacology

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