Effect of intravenous anesthetic propofol on synaptic vesicle exocytosis at the frog neuromuscular junction.
OBJECTIVE
To investigate the presynaptic effects of propofol, a short-acting intravenous anesthetic, in the frog neuromuscular junction.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Luciana Ferreira
LF
Leite
Renato Santiago
RS
Gomez
Matheus de Castro
Mde C
Fonseca
Marcus Vinicius
MV
Gomez
Cristina
C
Guatimosim
D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D005089:Exocytosis / Q000187:drug effects*; D005456:Fluorescent Dyes / Q000032:analysis; D009469:Neuromuscular Junction / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology*; D011726:Pyridinium Compounds / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D011892:Rana catesbeiana; D013572:Synaptic Vesicles / Q000187:drug effects*
D018686:Anesthetics, Intravenous; C073804:FM1 43; D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D015742:Propofol