Butylidenephthalide Blocks Potassium Channels and Enhances Basal Tension in Isolated Guinea-Pig Trachea

2018

Pharmaceutical Biology

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Context: The rhizome of Ligusticum chuaxiong Hort. (Umbelliferae) has been used by Chinese for several thousand years. Its main constituent, butylidenephthalide (Bdph), was proved to be active in inhibiting rat uterine contractions induced by prostaglandin F2α and was reported to be a nonspecific antispamodic and a blocker of voltage-dependent Ca2+ channels (VDCCs).Objectives: The present study investigates the mechanisms of Bdph for twitch facilitation in ICR mouse vas deferens (MVD).Materials and methods: Electrical field stimulation (EFS, supramaximal voltage ranging from 60–90 V, 1 ms, 0.2 Hz) was applied to the isolated MVD in Krebs solution. Interactions between Bdph (50 µM) and calcium antagonist (verapamil, diltiazem or aspaminol) on the EFS-evoked twitch responses were determined. The number of experiments was 3–18.Results: Bdph (50 µM)-induced twitch facilitations from 100 to 391.9% were unrelated to activation of postjunctional cholinergic or adrenergic receptors. Verapamil and Bdph unabolished the twitch facilitation each other. Diltiazem unabolished the Bdph-induced twitch facilitation. In contrast, Bdph abolished those induced by diltiazem. Aspaminol at 20 μM abolished the Bdph-induced twitch facilitation. In contrast, Bdph abolished those induced by aspaminol. Tetraethylammonium and 4-aminopyridine, the K+ channel blockers, significantly augmented the Bdph-induced twitch facilitation.Discussion and conclusions: Bdph may bind to the different, more and same subtypes of VDCCs from verapamil, than diltiazem, and as aspaminol does on prejunctional membrane, respectively. Besides a blocker of VDCCs, Bdph may be a blocker of K+ channels on prejunctional membrane. Thus, Bdph depolarized the membrane and facilitated the cumulative Ca2+-induced twitch responses.

Section: Discussionmentioning

confidence: 98%

Mechanisms of butylidenephthalide for twitch facilitation in electrically stimulated mouse vas deferens

Shih

2018

Pharmaceutical Biology

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“…Furthermore, Bdph, similar to 4-aminopyridine (Hsu et al. 2014), a voltage-gated K + channel blocker (Choquet and Korn 1992) blocked voltage-gated K + channels to induce membrane depolarization and facilitation. In the present study, Bdph (100 μM) significantly increased the electrically stimulated release of NA from the tissue into the medium.…”

Section: Discussionmentioning

confidence: 98%

“…Recently, we reported that Bdph similarly to 4-aminopyridine, a blocker of the Kv 1 family of K + channels, enhanced the baseline tension of the guinea-pig trachea (Hsu et al. 2014). The binding of Bdph to the K + channels of the smooth muscle cell membrane seems partially reversible, but the binding of Bdph to VDCCs seems irreversible.…”

Section: Discussionmentioning

confidence: 99%

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Butylidenephthalide facilitates contractions via nonspecific binding to receptors in isolated guinea-pig vas deferens

Shih

2019

Pharmaceutical Biology

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Context: Butylidenephthalide (Bdph) has been reported to inhibit rat uterine contractions, but significantly potentiate the noradrenaline (NA)-induced contractions in guinea-pig vas deferens (GPVDs). Objective: The present study elucidates the binding specificity of Bdph in GPVD to potentiate contractions. Materials and methods: Electrical field stimulation (EFS, supramaximal voltage, 1 ms and 1 Hz) or exogenous NA (50 μM) was applied to the GPVD in Krebs or 1/10 Mg-Tyrode’s solution, respectively. After the clonidine (10 nM)-induced twitch inhibition or the exogenous NA-induced contractions reached a constant, Bdph (50 µM) was added 2 min prior to the subsequent addition of NA (50 µM). Three experiments were performed. In the presence of Bdph (100 μM), the release of NA in the medium and remaining NA content in the tissues were determined after EFS-stimulation. Results: Bdph (100 μM) significantly antagonized the clonidine (10 nM)-induced twitch inhibition from 22.5 ± 2.1 to –11.4 ± 1.6% ( n = 6) and dibutyryl-cAMP (300 μM) from 25.7 ± 3.2 to 7.9 ± 4.0% ( n = 8). Bdph (100 μM) significantly increased the electrically stimulated release of NA from 393.0 ± 109.5 to 1000.0 ± 219.1 ng/g ( n = 6). Bdph (50 μM) potentiated the exogenous NA (50 μM)-induced contractions from 3.0 ± 0.06 to 3.9 ± 0.06 g ( n = 3), but after washout of Bdph, the response to NA gradually curtailed. Discussion and conclusions: Bdph action may be through the nonspecific binding of the butylidene group to prejunctional α 2 - and postjunctional α 1 -adrenoceptors to reversibly block K + channels, and irreversibly block VDCCs on the smooth muscle cell membrane, respectively.

“…Thus, when the K + channels were blocked and evoked prolonged repolarization, the nerve ending resulted in more excitability. Recently, we reported that Z-Bdph may be similar to 4-aminopiridine, a blocker of K v 1 family of K + channels, to enhance the baseline tension of guinea-pig trachea (Hsu et al 2014). There are two kinds of potassium channels, Kv1.3 and intermediate K + (IK) channel (K Ca 3.1), in T lymphocytes.…”

Section: Discussionmentioning

confidence: 99%

Lack of effect of Z-butylidenephthalide on presynaptic N-type Ca2+ channels in isolated guinea-pig ileum

Naunyn-Schmiedeberg's Arch Pharmacol

2015

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Z-Butylidenephthalide (Bdph) was reported to more potently inhibit electrically induced twitch responses than acetylcholine-induced tonic contraction in isolated guinea-pig ileum (GPI). The aim of the present study was to investigate the inhibitory effects of Z-Bdph on Ca2+ and K+ channels on GPI. In Locke-Ringer’s solution, both responses were isometrically recorded on a polygraph. Incubation of ω-conotoxin MVIIC, but not Z-Bdph, in the electrically stimulated GPI prior to adding ω-conotoxin GVIA, an irreversible blocker of N-type voltage-dependent Ca2+ channels (VDCCs), protected the binding sites and resulted in the twitch responses reversible by washing, suggesting that Z-Bdph did not bind to the N-type VDCCs. Interestingly, we found Z-Bdph concentration dependently delayed the onsets of K+-induced twitch responses, suggesting that Z-Bdph may be a blocker of K+ channels to interfere extracellular K+ across through the pre-junctional membrane of nerve ending in K+-free medium. Z-Bdph similar to nifedipine non-competitively inhibited cumulative ACh-induced phasic contractions, suggesting that Z-Bdph may bind to L-type of inositol-1,4,5-trisphosphate (IP3)-sensitive Ca2+ channels on the endoplasmic reticulum (ER) membrane. In the presence of verapamil, a L-type Ca2+ channel blocker or Z-Bdph, the twitch inhibitions by either were effectively reversed by exogenous Ca2+, suggesting that they may freely pass through pre-junctional N-type, but not L-type which was blocked at least a part by either, of VDDCs open when each electrical coaxial stimulation (ECS) into intracellular space of cholinergic nerve terminal and trigger release of transmitters. In conclusion, results confirm that Z-Bdph more potently inhibits ECS-induced twitch responses than ACh-induced PCs in GPI and suggest that this effect is not mediated by interaction with presynaptic N-type VDCCs.