Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Acta Pharmacol Sin. 2011 Jan;32(1):31-7. doi: 10.1038/aps.2010.175. Epub 2010 Nov 29.
To investigate the presynaptic effects of propofol, a short-acting intravenous anesthetic, in the frog neuromuscular junction.
Frog cutaneous pectoris nerve muscle preparations were prepared. A fluorescent tool (FM1-43) was used to visualize the effect of propofol on synaptic vesicle exocytosos in the frog neuromuscular junction.
Low concentrations of propofol, ranging from 10 to 25 μmol/L, enhanced spontaneous vesicle exocytosis monitored by FM1-43 in a Ca(2+)-dependent and Na(+)-independent fashion. Higher concentrations of propofol (50, 100, and 200 μmol/L) had no effect on spontaneous exocytosis. By contrast, higher concentrations of propofol inhibited the Na(+)-dependent exocytosis evoked by 4-aminopyridine but did not affect the Na(+)-independent exocytosis evoked by KCl. This action was similar and non-additive with that observed by tetrodotoxin, a Na(+) channel blocker.
Our data suggest that propofol has a dose-dependent presynaptic effect at the neuromuscular transmission which may help to understand some of the clinical effects of this agent on neuromuscular function.
研究短效静脉麻醉药异丙酚对青蛙神经肌肉接头突触前的作用。
制备青蛙皮胸神经-肌肉标本。使用荧光工具（FM1-43）来观察异丙酚对青蛙神经肌肉接头突触小泡胞吐作用的影响。
低浓度（10-25 μmol/L）的异丙酚以 Ca(2+)依赖和 Na(+)非依赖的方式增强由 FM1-43 监测的自发性囊泡胞吐。更高浓度的异丙酚（50、100 和 200 μmol/L）对自发性胞吐没有影响。相比之下，更高浓度的异丙酚抑制由 4-氨基吡啶诱发的 Na(+)依赖性胞吐，但不影响由 KCl 诱发的 Na(+)非依赖性胞吐。这种作用与钠离子通道阻断剂河豚毒素观察到的作用相似且无累加作用。
我们的数据表明，异丙酚在神经肌肉传递中具有剂量依赖性的突触前作用，这可能有助于理解该药物对神经肌肉功能的一些临床作用。
