[Neuromuscular Pharmacodynamics of Rocuronium in Diabetic Rats]

Objective To investigate diabetes-mediated changes in the neuromuscular pharmacodynamics of rocuronium in rats. Methods Diabetes mellitus was induced by a single injection of streptozotocin in rats.A total of 24 male SD rats were assigned to four groups using random number table:the normal control group,diabetic 2-week group,diabetic 4-week group,and diabetic 8-week group(6 rats per group).The sciatic nerve was stimulated in a rain-of-four(TOF)pattern,and the twitch tension changes in the tibialis anterior muscle were demonstrated by mechanomyography after intravenous injection of rocuronium in vivo.The time course characteristics of rocuronium,including onset time,and the recovery time from rocuronium injection to TOF ratio 75%(RT75%)and 90%(RT90%),were recorded,and half maximal inhibitory concentration(IC₅₀)values of rocuronium were determined using a four-parameter dose response curve. Results Compared with the normal controls,the diabetic rats had significantly prolonged onset time of rocuronium,while the RT75% and RT90% were decreased at all rocuronium doses(P<0.001).The time course changes became increasingly significant as the duration of diabetes lengthened(P<0.001).The IC₅₀ and 95% confidence interval values for rocuronium in the normal control group,diabetic 2-week group,diabetic 4-week group,and diabetic 8-week group were 0.37(0.35-0.38)mg/kg,0.44(0.43-0.46)mg/kg,0.59(0.57-0.61)mg/kg,and 0.64(0.61-0.66)mg/kg,respectively.IC₅₀ values were significantly higher in the diabetic groups vs.normal control(P<0.001)and gradually increased as the duration of diabetes lengthened(P<0.001).Conclusion Diabetes is associated with the rat skeletal muscle hyposensitivity to rocuronium,which is featured by prolonged onset time of rocuronium,decreased RT 75% and RT 90%,and right shift of the cumulative dose-response curve of rocuronium.