The Resistance To Non-depolarizing Muscle Relaxants And Mechanism In Acute Abdomen Rat Abdominal Muscle

BACKGROUND:Acute abdomen is the most common emergency.General anesthesia was commonly used in acute abdomen surgery in current,however,in general anesthesia more muscle relaxant dosage was needed to satisfy the muscle relaxation than normal patients.Muscle rigidity was often observed in patients with acute abdomen with general anesthesia surgery.It suggested that muscle relaxants by acting on neuromuscular junction could not block muscle contraction completely.In this situation muscle rigidity may be caused by intracellular overloaded calcium.The study on muscle sarcoplasmic reticulum function and intracellular calcium levels has not been reported in acute abdomen.The muscle function change and sarcoplasmic reticulum function and protein expression in rat skeletal muscles in acute abdomen were used to investigate the changes and study its possible mechanism in this study.METHODS:This study contains three parts:1)To investigate the changes of cytokines in rats in gastric perforation model and effects of rocuronium on abdominal pressure in rat with acute abdomen,volume-pressure curve:Thirty-six male sprague-dawley rats,weight 220-250g,were randomly divided into sham operation group（group C）,one hour group after perforation（group G1）,and two hours group after perforation（group G2）.After surgical perforation 2ED90 rocuronium was injected through the rat’s tail vein,intra-abdominal pressure changes were determinated and the curve of pressure volume was fitted.2)To investigate the effect of acute abdomen on rectus abdominis muscle function in rats.Rat rectus abdominis musclewas obtained for detection its function in vitro after surgical perforation:peak twitch tension（PT）,maximum peak rise and the maximum decline rate（±dmax/dt）,half relaxation time（1/2RT）,maximal tetanic tension（PO）,force frequency curve and fatigue index（FI）.3)To study the effect of acute abdomen on sarcoplasmic reticulum calcium release and uptake of calcium and Ca²⁺-ATPase（SERCA）activity of rat rectus muscle:After surgical perforation the rectus muscles were quickly obtained to homogenize in ice buffer liquid after weighting and saved in-80 degree Celsius.The changes of sarcoplasmic reticulum calcium uptake and release activity of Ca²⁺-ATPase in acute abdomen rat were detected.The levels of SERCA1,SERCA2 and Ryanodine receptor were determinate by Western blot.RESULTS:1.Statisticallycompared with the control group,the serum levels of IL-6 and TNF-α in the G2 group significantly increased.The volume-pressure relationship curves in the G1 and G2 groups were markedly shifted leftward（P<0.05）.Additionally,the IAP gradually decreased after the administration of rocuronium.However,the decrease in the IAP observed in the control group was markedly higher compared with the two GP groups（P<0.05）.2.The peak twitch tension in the G2 group was significantly lower than that in the control group（P<0.05）.In addition,the half-relaxation time（1/2RT）in the G2 group was significantly increased compared with that in the control group（P<0.01）.The peak tetanus tension in the G2 group was significantly higher than that in the control group（P<0.01）.The force-frequency curve for the sham group was significantly lower than those for the two GP groups（P<0.01）.The fatigue indices for both G1 and G2 groups were markedly lower than those for the control group.3.In rat rectus abdominis muscle,the peak rates of SR Ca²⁺uptake for whole muscle homogenate from animals in G1 and G2 were significantly（P<0.05）reduced by 50.7%and 47.7%,respectively,and the amount of Ca²⁺sequestered during loading was markedly reduced compared with the control group（P<0.05）.Conversely,the rates and amounts of Ca²⁺release evoked through AgN03 in GP animals were reduced compared with control rats.There was no significant difference in SERCA activity between groups.The evolution of AP in two hours did not cause a significant decrease in SERCAla or SERCA2a.Moreover,the RYR protein concentration was not significantly modified（P>0.05）.CONCLUSIONS:The serum levels of IL-6 and TNF-α in the G2 group increased signantly after the gastric perforation.The acute peritonitis induced through artificial gastric perforation attenuated the effect of rocuronium on abdominal wall muscle relaxatio1 after two hours of acute peritonitis.The sarcoplasmic reticulum Ca²⁺-ATPase uptake rate was impaired in acute peritonitis without a significant change in SERCA protein expression.