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|Type:||Artigo de periódico|
|Title:||The effects of Duvernoy's gland secretion from the xenodontine colubrid Philodryas olfersii on striated muscle and the neuromuscular junction: Partial characterization of a neuromuscular fraction|
|Abstract:||The effect of Philodryas olfersii Duvernoy's secretion was studied in vivo in mice and chicks as well as in the mouse phrenic nerve-diaphragm and the chick biventer cervicis preparations. The whole secretion (20-40 mu g/ml) increased the creatine kinase (CK) levels in mice but had no effect on the mouse phrenic nerve-diaphragm preparation, In the chick, the secretion caused head drop and paresia as well as irreversible blockade of the twitch-tension evoked by indirect stimulation in the chick biventer cervicis preparation (50% paralysis in 34.5 +/- 2.7 min, n = 4). The secretion also caused muscle contracture (30% of the maximal twitch-tension generated) after a latency of nearly 9 min. Following fractionation on a Superose 12 FPLC column, the neuromuscular activity was recovered in the high mol, wt fraction (Peak I). At a concentration of 10 mu g/ml in the chick biventer cervicis preparation, Peak I caused 50% paralysis within 18.5 +/- 3.0 min (n = 4), and evoked a strong contracture (70%, of the maximal twitch-tension generated). The contractile responses of the chick preparation to ACh and KCl were partially blocked (90%) by the whole secretion and totally blocked by Peak I. CK release was increased by the whole secretion but not by Peak I. The whole secretion also produced various degrees of muscle cell lysis and extensive widening of the intercellular spaces. The latter showed a loosely arranged membranous network. In general, Peak I caused only minor morphological alterations compared with the whole secretion, although these were still significantly different from those observed in the control preparations. The changes principally involved hypercontraction of the muscle fibers. Based on the above results, we conclude that Peak I contains the factor(s) responsible for the in vitro effects on neuromuscular transmission, whereas the direct myotoxic effect is apparently caused by at least one other component of the Duvernoy's secretion. (C) 1996 Elsevier Science Ltd.|
|Editor:||Pergamon-elsevier Science Ltd|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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