We have investigated the effects of adenosine i.v. on neuromuscular block i
nduced by rocuronium, vecuronium and pipecuronium in an in vivo guinea-pig
sciatic nerve-tibialis anterior preparation. The ED50 Of each neuromuscular
blocker was determined from cumulative log dose-response regression lines
(n = 14). In separate experiments, adenosine 0.1 mg kg(-1) min(-1) or the s
ame volume of 0.9% NaCl was given i.v. via a constant infusion and the ED50
Of each neuromuscular blocking agent was then administered (n = 24). Adeno
sine 0.1 mg kg(-1) min(-1) increased significantly maximal block induced by
the ED50 of these neuromuscular blockers (55-72%, 49-73% and 60-96%, respe
ctively, for rocuronium, vecuronium and pipecuronium; P < 0.05). Time to ma
ximal block after rocuronium was significantly prolonged by adenosine (1.4-
2.1 min; P < 0.05) and time to maximal block after vecuronium and pipecuron
ium was unchanged by adenosine. Time to maximal recovery of twitch tension
after administration of the ED50 of all neuromuscular blocking agents was p
rolonged significantly by adenosine (4.5-10.7 min, 8.2-15.8 min and 47.0-12
8.7 min, respectively, for rocuronium, vecuronium and pipecuronium; P < 0.0
5). We conclude that continuous infusion of adenosine 0.1 mg kg(-1) min(-1)
potentiated the effects of neuromuscular blocking agents in this in vivo g
uinea-pig preparation.