Drug actions at mammalian motor nerve endings: the suppression of neostigmine-induced fasciculations by vecuronium and isoflurane.
The occurrence of fasciculations following administration of agents is a well-known pharmacologic phenomenon. Using the cat soleus nerve-muscle preparation, intravenous neostigmine doses between 20-200 micrograms/kg evoked fasciculations in a dose-related manner. The data demonstrate that the fasciculations were the result of the direct effect of neostigmine acting at the motor nerve endings. Vecuronium in a dose-related manner (3 and 5 micrograms/kg iv) suppressed this prejunctional activity of neostigmine. The prejunctional effect of vecuronium explains its effectiveness in preventing succinylcholine-induced fasciculations. In the presence of isoflurane (end-tidal concentration 0.20-0.25%), the suppressant effect of vecuronium on motor nerve endings was enhanced. The prejunctional action of isoflurane may be a major contribution to the additive effects of non-depolarizing muscle relaxants and potent inhalation agents.
D000818:Animals; D002415:Cats; D005207:Fasciculation / Q000139:chemically induced / Q000517:prevention & control*; D007530:Isoflurane / Q000627:therapeutic use*; D009046:Motor Neurons / Q000187:drug effects; D009132:Muscles / Q000294:innervation; D009388:Neostigmine / Q000037:antagonists & inhibitors*; D009411:Nerve Endings / Q000187:drug effects; D014673:Vecuronium Bromide / Q000627:therapeutic use*
D009388:Neostigmine; D014673:Vecuronium Bromide; D007530:Isoflurane