Selective release of ATP from sympathetic nerves of rat vas deferens by the toxin TsTX-I from Brazilian scorpion Tityus serrulatus

Selective release of ATP from sympathetic nerves of rat vas deferens by the toxin TsTX-I from Brazilian scorpion Tityus serrulatus

Author Conceição, Isaltino Marcelo da Autor UNIFESP Google Scholar
Jurkiewicz, Aron Autor UNIFESP Google Scholar
Fonseca, Daniela R. Google Scholar
Opperman, Andrea R. Google Scholar
Freitas, Thalma A. Google Scholar
Lebrun, Ivo Google Scholar
Garcez-do-Carmo, Lúcia Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Butantan Inst
Universidade de São Paulo (USP)
Abstract 1 the effects of the main component of the Tityus serrulatus scorpion venom, toxin TsTX-I, were studied on the contractility and release of neurotransmitters in the rat vas deferens. Since TsTX-I is known to act on sodium channels, we used veratridine, another sodium channel agent, for comparison.2 Toxin TsTX-I induced concentration-dependent contractions with an EC50 value of 47.8+/-0.1 nM and a maximum effect of 84.4+/-10.4% of that for BaCl2.3 Contractions by TsTX-I were abolished by denervation or tetrodotoxin (0.1 muM), showing that the toxin effects depend on the integrity of sympathetic nerve terminals.4 To check for the presence of a noradrenergic component, experiments were conducted after removal of adrenergic stores in nerve terminals by reserpinization (10 mg kg(-1), 24 h prior to experiments) or blockade of alpha(1) adrenoceptors by prazosin (30 muM), showing that these procedures did not modify the response to TsTX-I, and therefore that adrenoceptors were not involved in contractions.5 To check for the presence of a purinergic component, experiments were carried out after blockade of P-2X receptors by suramin (0.1 mM) or desensitization by alpha,beta-methylene-ATP (30 muM). These agents greatly abolished the contractile response to TsTX-I (about 83% by desensitization and 96% by suramin), showing the involvement of purinergic receptors.6 the release of noradrenaline and purinergic agents (ATP, ADP, AMP and adenosine) was detected by HPLC. Together, the total release of purines in the presence of TsTX-I was about 42 times higher than in the control group. in contrast, TsTX-I did not modify the overflow of noradrenaline, showing that the release was selective for purines.7 the release of purinergic agents was reduced by the N-type calcium channel blocker omega-conotoxin GVIA (1 muM) and by the P/Q-type blocker omega-conotoxin MVIIC (1 muM), showing that the effects of TsTX-I are calcium-dependent.8 the results show that TsTX-I produced a selective release of purines from postganglionic sympathetic nerves in the rat vas deferens.
Keywords VAS deferens
toxin TsTX-I
cotransmission
ATP
adrenoceptors
Language English
Date 2005-02-01
Published in British Journal of Pharmacology. London: Nature Publishing Group, v. 144, n. 4, p. 519-527, 2005.
ISSN 0007-1188 (Sherpa/Romeo, impact factor)
Publisher Nature Publishing Group
Extent 519-527
Origin http://dx.doi.org/10.1038/sj.bjp.0706062
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000227330600009
URI http://repositorio.unifesp.br/handle/11600/28121

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