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|Type:||Artigo de periódico|
|Title:||New evidence for a presynaptic action of prednisolone at neuromuscular junctions|
|Author:||Dal Belo, CA|
|Abstract:||The action of prednisolone at the neuromuscular junction was studied in mouse isolated phrenic nerve-diaphragm and rat external popliteal/sciatic nerve-tibialis anterior muscle preparations. Prednisolone (0.03 mM and 0.3 mM) did not alter the twitch-tension in phrenic nerve-diaphragm preparations after 120 min, but increased the frequency (170 +/- 4%) and amplitude (200 +/- 13%) of miniature end-plate potentials. Quantal content was not influenced by the glucocorticoid treatment. Prednisolone (400 mug/kg) did not change the twitch-tension in rat external popliteal/sciatic nerve-tibialls anterior muscle preparations. However, this steroid (0.3 mM) prevented the neuromuscular blockade by d-tubocurarine (1.45 muM) in mouse preparations by 70 +/- 10% (P < 0.05). A similar effect (82 +/- 6% protection, P < 0.05) occurred in rats treated with prednisolone (400 mug/kg) before d-tubocurarine (225 mug/kg). In phrenic nerve-diaphragm preparations, prednisolone (0.3 mM) increased (13 4%, p < 0.05) the twitch-tension in the presence of β-bungarotoxin (1 μM), and prevented the blockade produced by this toxin (0.15 μM) in its third phase of action. This presynaptic facilitatory effect may contribute to the usefulness of prednisolone in myasthenia gravis. (C) 2002 Wiley Periodicals, Inc.|
|Editor:||John Wiley & Sons Inc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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