Effects of Synthetic ω-Conotoxin on the Contractile Responses of Segments of Rat Ileum, Stomach Fundus and Uterus and Guinea Pig Taenia Coli

Ichida, Seiji; Oka, Hiroaki; Masada, Atsuhiro; Fujisue, Takashi; Hata, Taeko; Matsuda, Narihisa

doi:10.1254/jjp.48.395

Cited by 12 publications

(9 citation statements)

References 15 publications

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“…It has been found that high concentrations of conotoxin (O.3-1O0M) produced contractions of rat gastric fundus and uterus, and enhanced responses of the uterus to acetylcholine and KCI (Ichida et al, 1988). We did not observe any such effects with the lower concentrations of conotoxin used in any of the tissues we studied.…”

Section: Effects Ofconotoxin On Nanc Transmissioncontrasting

confidence: 63%

Effects of ω‐conotoxin GVIA on autonomic neuroeffector transmission in various tissues

Luca

Rand

et al. 1990

British J Pharmacology

101

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1 The effects of co-conotoxin GVIA (conotoxin), a potent inhibitor of neuronal N-type Ca2+ channels, have been examined on responses to stimulation of noradrenergic, cholinergic and non-adrenergic, noncholinergic (NANC) nerves in a range of isolated tissues to investigate the role of conotoxin-sensitive Ca2 + channels in neurotransmission. 2 Contractions elicited by field stimulation of noradrenergic nerves in rat and mouse anococcygeus muscles, rabbit ear artery and rat vas deferens (epididymal portion) were inhibited by conotoxin. Responses to noradrenaline, and to adenosine triphosphate in the vas deferens, were not affected. 3 Positive chronotropic responses to field stimulation of noradrenergic nerves were inhibited by conotoxin in rat and mouse atria, but responses to noradrenaline and tyramine were not affected. 4 The stimulation-induced release of noradrenaline was inhibited by conotoxin in the rabbit ear artery and in rat and mouse atria. 5 Relaxations in response to stimulation of the noradrenergic perivascular mesenteric nerves were reduced or abolished by conotoxin in rat and rabbit jejunum. The response to noradrenaline in rat jejunum was not affected. 6 Contractions elicited by stimulation of cholinergic nerves were inhibited by conotoxin in rat jejunum and mouse ileum (perivascular mesenteric nerves), and in guinea-pig taenia caeci (field stimulation). Responses to acetylcholine in rat jejunum and mouse ileum were not affected. 7 Contractions elicted by stimulation of the cholinergic plus NANC pelvic nerves were inhibited by conotoxin in rabbit colon, and to a lesser extent in guinea-pig colon. The stimulation-induced contraction of the guinea-pig colon was inhibited by conotoxin by a greater proportion in the presence than in the absence of atropine. Responses to acetylcholine were not affected in the rabbit colon but were slightly reduced in the guinea-pig colon. 8 Relaxations in response to field stimulation of NANC nerves were inhibited by conotoxin in guineapig taenia caeci and rat gastric fundus strips, and in rat anococcygeus muscle when the tone was raised by guanethidine but not when it was raised by carbachol. The relaxations produced by sodium nitroprusside in the rat gastric fundus and anococcygeus were not affected. 9 Contractions of the rat bladder elicited by stimulation of the peri-urethral nerves, which are NANCand cholinergically mediated, were relatively insensitive to inhibition by conotoxin. The responses were almost completely abolished by tetrodotoxin. 10 The conotoxin-induced inhibitions of responses to nerve stimulation developed slowly and persisted after removal of conotoxin.11 The inhibitory effect of conotoxin was inversely proportional to the frequency of stimulation (in several preparations) and to the Ca2+ concentration in the bathing solution (in rat vas deferens). These observations suggest that the inhibition by conotoxin of the Ca2+ influx required for excitation-secretion coupling in autonomic nerve terminals is not absolute, and can be overcome by repeated st...

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Section: Effects Ofconotoxin On Nanc Transmissioncontrasting

confidence: 63%

Effects of ω‐conotoxin GVIA on autonomic neuroeffector transmission in various tissues

Luca

Rand

et al. 1990

British J Pharmacology

101

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“…From the previous experiments performed in our lab, we have experienced that at least rat stomach fundus tends to be more responsive to spasmogenics than to spasmolytics, particularly when a combination of these stimulant and relaxant constituents coexists (41). There have also been reports in the literature on the specific spasmogenic activity of particular compounds in rat stomach fundus that had a spasmolytic effect in other tissues from rat and other species (42,43). On the other hand, rat stomach fundus has been reported to be less responsive to spasmolytic activity (44,45).…”

Section: Discussionmentioning

confidence: 99%

Pharmacological Basis for the Medicinal Use of Ginger in Gastrointestinal Disorders

2005

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Ginger (rhizome of Zingiber officinale) has been widely used for centuries in gastrointestinal disorders, particularly dyspepsia, but its precise mode of action has yet to be elucidated. This study was undertaken to study the prokinetic action of ginger and its possible mechanism of action. Prokinetic activity of ginger extract (Zo.Cr) was confirmed in an in vivo test when it enhanced the intestinal travel of charcoal meal in mice. This propulsive effect of the extract, similar to that of carbachol, was blocked in atropine-pretreated mice, a standard cholinergic antagonist. Likewise, Zo.Cr showed an atropine-sensitive dose-dependent spasmogenic effect in vitro as well as in isolated rat and mouse stomach fundus tissues. In atropinized tissue, it showed spasmolytic activity as shown by the inhibition of 5-HT- and K+-induced contractions. A spasmolytic effect was also observed in other gut preparations either as noncompetitive inhibition of agonist dose-response curves, inhibition of high K+(80 mM)-induced contractions, or displacement of Ca2+ dose-response curves to the right, indicating a calcium antagonist effect. Phytochemical analysis revealed the presence of saponins, flavonoids, and alkaloids in the crude extract. These data indicate that Zo.Cr contains a cholinergic, spasmogenic component evident in stomach fundus preparations which provides a sound mechanistic insight for the prokinetic action of ginger. In addition, the presence of a spasmolytic constituent(s) of the calcium antagonist type may explain its use in hyperactive states of gut like colic and diarrhea.

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“…These con tractile responses to omega-CgTX depended upon the presence and/or the influx of ex tracellular calcium and these responses were inhibited by calcium antagonists, suggesting that omega-CgTX might have a calcium agonist-like effect on smooth muscles (6). However, omega-CgTX caused only a nega tive inotropic response in the isolated, blood perfused dog atrium.…”

mentioning

confidence: 93%

“…It was reported that omega-CgTX caused dose-dependent contraction in segments of the rat stomach fundus and uterus (6). These con tractile responses to omega-CgTX depended upon the presence and/or the influx of ex tracellular calcium and these responses were inhibited by calcium antagonists, suggesting that omega-CgTX might have a calcium agonist-like effect on smooth muscles (6).…”

mentioning

confidence: 97%

“…However, the responses to exogenous administration of noradrenaline, acetylcholine and adenosine triphosphate are not affected by omega-CgTX in the same preparations (5). In 1988, Ichida et al (6) reported that a synthetic omega CgTX itself caused a dose-dependent contrac tion of segments of the stomach fundus and uterus. They suggested that omega-CgTX might have a calcium agonist-like effect on smooth muscles.…”

mentioning

confidence: 99%

See 1 more Smart Citation

A Negative Inotropic Effect of Omega-Conotoxin GVIA in Isolated, Blood-Perfused Dog Right Atria.

Ren¹,

Furukawa²,

Karasawa³

et al. 1991

Jpn.J.Pharmacol

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ABSTRACT-Using an isolated, blood-perfused canine atrial preparation, we investi gated the effects of omega-conotoxin GVIA (omega-CgTX), a blocker of N-type voltage-operated calcium channels, on the atrial contractile force and sinus rate. Omega-CgTX in a dose range of 0.3 3 nmol gradually attenuated the atrial contrac tile force in a dose-dependent manner, but did not affect the sinus rate, indicating that it can depress contractility but not pacemaker activity.

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Effects of Synthetic ω-Conotoxin on the Contractile Responses of Segments of Rat Ileum, Stomach Fundus and Uterus and Guinea Pig Taenia Coli

Cited by 12 publications

References 15 publications

Effects of ω‐conotoxin GVIA on autonomic neuroeffector transmission in various tissues

Effects of ω‐conotoxin GVIA on autonomic neuroeffector transmission in various tissues

Pharmacological Basis for the Medicinal Use of Ginger in Gastrointestinal Disorders

A Negative Inotropic Effect of Omega-Conotoxin GVIA in Isolated, Blood-Perfused Dog Right Atria.

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