THE EFFECT OF SUCCINYLCHOLINE ON ENERGY-METABOLISM STUDIED BY P-31-NMR SPECTROSCOPY IN RAT DENERVATED SKELETAL-MUSCLE

Background: The goals of this study were: (1) to demonstrate the diffe rences of metabolic changes induced by succinylcholine (SCh) administr ation between normal and denervated muscle by P-31-NMR spectroscopy: ( 2) to determine whether three kinds of drugs (vecuronium, midazolam an d magnesium sulfate) could prevent these metabolic changes. Methods: F ollowing unilateral sciatic nerve section, 20 male Wistar rats were st udied at three-week intervals. After SCh 1 mg . kg(-1) was administere d intravenously, the changes of the inorganic phosphate/phosphocreatin e (Pi/PCr) ratio, the beta ATP/(PCr+Pi) ratio, and intracellular pH we re measured by P-31-NMR both in normal and denervated hind limb muscle s of 5 rats. The other 15 rats were allocated to the pretreatment grou ps by the following drugs: vecuronium 0.02 mg . kg(-1), midazolam 0.1 mg . kg(-1) and magnesium sulfate 60 mg . kg(-1). After pretreatment 3 min before SCh administration, we measured the same parameters by P-3 1-NMR. Results: SCh administration did not change the Pi/PCr ratio in normal muscle, but significantly increased that in denervated muscle ( P<0.05). This increase of the Pi/PCr ratio was also observed in all pr etreated groups but was minimal as compared with that in non-pretreatm ent denervated muscle. Conclusion: These data suggested that SCh admin istration decreased the level of ''energy reserve'' in denervated musc le, and that this metabolic change was not totally inhibited by vecuro nium, midazolam, or magnesium sulfate.