Inhibitory action of capsaicin on cholinergic responses induced by GABAA agonists in the guinea-pig ileum

Tonini, Marcello; Onori, L.; Rizzi, C.A.; Ponti, Fabrizio De; Perucca, Emilio; Budassi, Piero; Crema, A.

doi:10.1016/0014-2999(86)90777-6

Cited by 4 publications

(1 citation statement)

References 10 publications

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“…This is not the first time an interaction has been described between GABA and capsaicin-sensitive nerves in the periphery. Tonini et al (1986) showed that capsaicin (0.2pM given 30min before) attenuated the contractile response to GABAA receptor agonists in the guinea-pig isolated ileum (see also Tonini et al, 1987). From these experiments the authors concluded that capsaicin-sensitive nerves might be involved in the action of GABA in this tissue.…”

Section: Discussionmentioning

confidence: 95%

GABA_A receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves

Maggi

Giuliani

Manzini

et al. 1989

British J Pharmacology

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1 Isolated left atria from reserpine-pretreated guinea-pigs, electrically driven (3 Hz) in the presence of atropine (1.uM), phentolamine (0.3 pM) and propranolol (1I M), responded to a train of stimuli (10 Hz for 2.5 s) with a delayed neurogenic positive inotropic response which was insensitive to hexamethonium (10pM) but abolished by either tetrodotoxin (1 pM), w..conotoxin (0.1 pM), in vitro capsaicin desensitization or desensitization to calcitonin gene-related peptide (CGRP). 2 In these experimental conditions, y-aminobutyric acid (GABA) produced a concentration-related (10.pM-1 mM) positive inotropic response similar to that produced by electrical field stimulation.The effect of GABA was competitively antagonized by bicuculline methiodide (10pM), a GABAA receptor antagonist. 3 The selective GABAA receptor agonists, muscimol and homotaurine mimicked the positive inotropic effect of GABA while baclofen, the selective GABAB receptor agonist, did not. 4 The action of GABA (1 mM) was abolished by either tetrodotoxin (1 pM), c-conotoxin (0.1 pM), in vitro capsaicin desensitization or desensitization to CGRP, while it was unaffected by hexamethonium. In contrast, the inotropic response to CGRP was unaffected by tetrodotoxin, cwconotoxin, bicuculline methiodide, hexamethonium or in vitro capsaicin desensitization, but was abolished by CGRP desensitization. 5 In the spontaneously beating guinea-pig right atrium, GABA (1 pM) produced a small and transient positive chronotropic effect that was no longer observed after in vitro desensitization with capsaicin (1 PM). 6 In the guinea-pig isolated perfused heart from reserpine-pretreated animals (with atropine, phentolamine and propranolol in the perfusion medium), GABA (1 pM) produced a transient tachycardia and a small increase in coronary flow. Both capsaicin (1 pM) and CGRP (1 pM) produced marked tachycardias and increases in coronary flow. After exposure to capsaicin (1 pM), no effect of GABA could be detected. 7 We conclude that, in the guinea-pig heart, GABAA receptors, presumably located on the preterminal region of capsaicin-sensitive sensory nerves, initiate a conducted impulse (since it is tetrodotoxin-sensitive) which leads to transmitter release (endogenous CGRP-like material) by activation of co-conotoxin-sensitive, voltage-sensitive calcium channels and a functional response.

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Section: Discussionmentioning

confidence: 95%

GABA_A receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves

Maggi

Giuliani

Manzini

et al. 1989

British J Pharmacology

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The Role of GABA in the Peripheral Nervous System

Tanaka¹,

Taniyama²

1992

GABA Outside the CNS

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GABA and Gut Motility

Kerr¹,

Ong²

1992

GABA Outside the CNS

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Inhibitory action of capsaicin on cholinergic responses induced by GABAA agonists in the guinea-pig ileum

Cited by 4 publications

References 10 publications

GABA_A receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves

GABA_A receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves

The Role of GABA in the Peripheral Nervous System

GABA and Gut Motility

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Inhibitory action of capsaicin on cholinergic responses induced by GABAA agonists in the guinea-pig ileum

Cited by 4 publications

References 10 publications

GABAA receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves

GABAA receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves

The Role of GABA in the Peripheral Nervous System

GABA and Gut Motility

Contact Info

Product

Resources

About

GABA_A receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves

GABA_A receptor‐mediated positive inotropism in guinea‐pig isolated left atria: evidence for the involvement of capsaicin‐sensitive nerves