Biophysical, histopathological and pharmacological characterization of crotamine isoforms F22 and F32.
Toxicon
; 41(4): 493-500, 2003 Mar.
Article
em En
| MEDLINE
| ID: mdl-12657319
Two major crotamine isoforms (F22 and F32) were obtained after three chromatographic steps and were assayed in mouse phrenic nerve-diaphragm preparations. F32 and F22 (0.5 microg/ml, n=4) produced a facilitatory effect, which increased isometric twitch-tension by 300 and 230%, respectively, after a 120 min incubation. At a concentration of 0.1 microg/ml, both isoforms increased the twitch-tension by about 160%. However, when the isoforms were co-incubated (final concentration, 0.5 microg/ml) for 30 min prior to testing, they did not cause the facilitation seen with > or =0.1 microg/ml of each isoform alone. Histologically, F32 and F22 at 0.5 and 1 microg/ml were quantitatively alike in inducing tissue myonecrosis. However, a mixture of the two isoforms (final concentration, 0.5 microg/ml) significantly attenuated the damage seen with either toxin alone. Mass spectrometry analysis showed that the isoforms had the same molecular mass (4.8 kDa) and that they existed as monomers with a highly stable structure. These results indicate that F22 and F32 acted on muscle cells of the mouse phrenic-nerve diaphragm preparation through similar mechanisms. Since the isoforms did not produce the expected summation in the increase in muscle twitch-tension, it is possible that they may have different affinities for the sodium channel subunits.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Venenos de Crotalídeos
Limite:
Animals
Idioma:
En
Revista:
Toxicon
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Reino Unido