Adenosine potentiation of neuromuscular blocking agents in guinea-pigs

We have investigated the effects of adenosine i.v. on neuromuscular block induced 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 same 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). Adenosine 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%, respectively, for rocuronium, vecuronium and pipecuronium; P < 0.05). Time to maximal block after rocuronium was significantly prolonged by adenosine (1.4-2.1 min; P < 0.05) and time to maximal block after vecuronium and pipecuronium was unchanged by adenosine. Time to maximal recovery of twitch tension after administration of the ED50 of all neuromuscular blocking agents was prolonged significantly by adenosine (4.5-10.7 min, 8.2-15.8 min and 47.0-128.7 min, respectively, for rocuronium, vecuronium and pipecuronium; P < 0.05). 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 guinea-pig preparation.