Effect of ω-agatoxin-IVA on autonomic neurotransmission
1994; Elsevier BV; Volume: 261; Issue: 1-2 Linguagem: Inglês
10.1016/0014-2999(94)90303-4
ISSN1879-0712
Autores Tópico(s)Neurobiology and Insect Physiology Research
Resumoω-Agatoxin-IVA, a peptide from the venom of the funnel-web spider Agelenopsis aperta and a P type Ca2+ channel inhibitor, was examined for effects on responses to nerve stimulation in isolated autonomic neuroeffector preparations from the rabbit, guinea-pig and rat. Ca2+-dependent, tetrodotoxin sensitive, noradrenergic excitatory responses of rabbit pulmonary artery, rat vas deferens, and anococcygeus muscles, and cholinergic guinea-pig myenteric plexus preparations (all highly sensitive to the N type Ca2+ channel inhibitor ω-conotoxin-GVIA) were unaffected by ω-agatoxin-IVA (100 nM). Similarly, the neurogenic response of rat bladder, which has cholinergic, and non-adrenergic non-cholinergic (NANC) excitatory components, and the NANC inhibitory response of rat jejunum (atropine 0.5 μM- and guanethidine 5.0 μM-treated), which are partially sensitive and insensitive to ω-conotoxin-GVIA, respectively, were unaffected by ω-agatoxin-IVA (100 nM). Neurogenic NANC inhibitory responses of the guinea-pig taenia caecum, and rat anococcygeus muscles (atropine- and guanethidine-treated, and tone raised with prostaglandin F2α), were also insensitive to ω-agatoxin-IVA. These results suggest that P type Ca2+ channels, if present, play an insignificant role in supplying the Ca2+ necessary for neurotransmitter release in the peripheral autonomic nervous system.
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