Dose response relationship for recuronium and succinylcholine on different muscles preparation

ABSTRACT

Twenty male rabbits weighing 1-1.5 kg were anaesthesized and gastrocnemius, orbicularis oris, and orbicularis oculi muscles were prepared. They were divided into two equal groups according to relaxant received. First group were injected intravenously [I.V.] by serial doses of rocuronium, starting by small effective doses till a complete blocking dose to all muscles prepared [100% muscle twitch depression]. The second group received succinylcholine by serial doses, to complete blocking dose to all muscles prepared. The% twitch depression, onset time of the effective dose that lead to 90% twitch depression and its duration of action from injection to 90% recovery of the twitch height, and the effective dose 50 for each muscle was determined.It was found that gastrocnemius muscle was the first to be affected by both rocuronium and succinylcholine with short onset time and prolonged duration of action than other two muscles which showed earlier recovery. The effective dose with 50% twitch highest depression [ED50] in both groups of muscles due to recuronium and succinylcholine were compared. We concluded that gastrocnemius muscle was the first muscle to be affected by depolarizing and non depolarizing muscle relaxants and fascial muscles were lately affected with earlier recovery. The complication of these findings were discussed