| Bupivacaine is one of lipid soluble amide long-acting local anesthetics as a commonlyused in clinic. It can induce local anesthetic systemic toxicity when plasma bupivacaineconcentration grow fast as a result of accidental intravascular or intrathecal injection oradministration of an excessive dose. Systemic reactions to local anesthetics primarily involvethe central nervous system (CNS) toxicity and the cardiovascular system. A lot of laboratorystudies and clinical reports have shown that infusion of lipid can reliably reversecardiovascular collapse (CC) which is induced by bupivacaine. But there is still controversiesthat how to use epinephrine combination in lipid resuscitation protocols. In this study, thechapter one was established the model of New Zealand rabbits’s cardiotoxicity induced bycontinuous bupivacaine intravenous infusion. Then used this model to performed to assess theeffect of lipid emulsion combined with epinephrine of three different doses to resuscitate thecardiovascular collapse induced by bupivacaine. In vivo and in vitro experiments had showedthat bupivacaine could leading to cell apoptosis.In chapter two we researched the effect oflipid emulsion is associated with inhibition of the apoptosis of H9c2cells caused bybupivacaine and the target for anti-apoptosis of decrease mitochondria membrane potential inthis protection processing.Part1: Establishment of the model of New Zealand rabbits’s cardiotoxicity induced bycontinuous bupivacaine intravenous infusionObjective This study was to establish the model of New Zealand rabbits’s cardiotoxicityinduced by continuous bupivacaine intravenous infusion.Methods Fourteen pentobarbital-anesthetized rabbits were given endotracheal intubation and mechanical ventilation (100%oxygen). All the animals were randomly divided into2groups: control group (group C) and group L. After a30minutes stabilization period,bupivacaine was administered at a rate of1.5mg·(kg·min)-1until the heart rate decreased to60beats/min and the mean blood pressure were below to20mmHg. Once reached the pointand maintained10s, external chest compressions were started immediately. At1minute,group L (n=7) were received3mL·kg-120%intralipid and followed by a continuously infusedat the rate of0.5mL·(kg·min)-1. While the group C (n=7), received3mL·kg-10.9%salineand followed by a continuously infused at the rate of0.5mL·(kg·min)-1. The ECG andarterial pressure were continuously monitored to20minutes. Arterial blood gas analysis weredone at the time of T0and T4.Results Mean blood pressure and Heart Rate at group L and C were lower than the baseline,and group L was significantly higher than group C at T1, T2, T3, T4(P<0.05). The data of pH,PaO2at T4, the group L was significantly higher than group C (P<0.05); And the data ofLactic acid, PaCO2in group C was significantly higher than group L (P<0.01).Conclusion The model of intravenous injection bupivacaine in rabbits to cause cardiotoxicitywas successes.In this model, the lipid emulsion was more effectively than saline in theresuscitation.Part2: A comparison of lipid combined with epinephrine in resuscitating the cardiotoxicityafter intravenous injection of bupivacaine in rabbitsObjective This study was performed to assess the effect of lipid emulsion combined withepinephrine of three different doses to resuscitate the cardiovascular collapse induced bycontinuous bupivacaine intravenous infusion.Methods Thirty five pentobarbital-anesthetized rabbits were given endotracheal intubationand mechanical ventilation (100%oxygen). All the animals were randomly divided into5groups. After a30minutes stabilization period, bupivacaine was administered at a rate of1.5 mg·(kg·min)-1until the heart rate decreased to60beats/min and the mean blood pressurewere below to20mmHg. Once reached the point and maintained10s, external chestcompressions were started immediately. At1minute, group L, L5, L25, L50(n=7) werereceived3mL·kg-120%intralipid and followed by a continuously infused at the rate of0.5mL·(kg·min)-1. Additionally, the group L5, L25, L50, were infused epinephrine5,25,50μg·kg-1respectively. While the group C (n=7), received3mL·kg-10.9%saline andfollowed by a continuously infused at the rate of0.5mL·(kg·min)-1. The ECG and arterialpressure were continuously monitored to20minutes. The numbers of rabbits which return ofspontaneous circulation were record at T1, T2, T3, T4.Results Mean blood pressure at T1, group L5, L25, L50were significantly higher than groupC, L (P<0.05), and group L25, L50were significantly higher than group L5, group L50wassignificantly higher than group L25(P<0.05). MAP at T2, group C was significantly lowerthan other four groups, group L25was significantly higher than group L5(P<0.05); GroupL,L5, L25were significantly higher than group C at T3, T4(P<0.05); MAP at T4, groupL25wassignificantly higher than group L50(P<0.05). HR in group C, L, L5were significantly lowerthan group L25and group L50at T1(P<0.05). HR at T2, group L25, L50were significantlylonger than group C (P<0.05); HR in group C was significantly lower than other four groupsat T3, T4(P<0.05); HR at T4group L25was significantly higher than group L50(P<0.05). PRduration and QRS duration in group C were significantly longer than other four groups(P<0.05), but group C, L, L50were significantly longer than the baseline (P<0.05) at T4.After20minutes, five of seven rabbits in group lipid emulsion plus a single25μg·kg-1epinephrine injection survived.Conclusion In this model, the cardiovascular collapse induced by bupivacaine can beeffectively reversed by the lipid emulsion combined with a single epinephrine injection of25μg·kg-1. Part3The inhibitory action of lipid emulsion on the apoptosis induced by bupivacaine inH9c2cellsObjective To investigate the effect of lipid emulsion on apoptosis induced by bupivacaineand research the target for anti-apoptosis effection.Method H9c2cells were treated with different drugs for24hours:cell with DMEM (groupControl),1.03mmol/L bupivacaine (group Bup),2%lipid emulsion (group LE),2%LE+1.03mmol/L bupivacaine (group LE+Bup). Cell apoptosis were investigated withflowcytometry. In addition, mitochondrial membrane potential and the survival rate(determined by MTT method) were studied. Cleaved caspase-3and caspase-3expressionWestern blot.Results There were significant difference among groups (F=78.460； F=227.108；F=173.471；F=164.346；F=165.463；all P values<0.01) in cell survival rate, apoptotic, JC-1polymer/monomer, Cleaved Caspase-3protein and the ratio of Cleaved Caspase-3/Caspase-3.Cell survival rate in group Bup was lower than the other three groups（P<0.01）, the rate inLE+Bup group much higher than Bup group and lower than group Control (P<0.05). Therewas significant difference between group Bup and other groups on apoptotic rate (P<0.01),in group LE+Bup was higher than that in Control, LE group and lower than that in Bupgroup (all P values<0.01). The ratio of polymer/monomer in group Bup (0.32±0.03) waslower than Control group (0.96±0.65）（P<0.01），and the ratio in LE+Bup group (0.46±0.04) was higher than Bup group (P<0.01). Caspase-3, Cleaved Caspase-3protein weremeasured by Western blot, there were no significant difference in all groups and bupivacaineincreased the level of Cleaved Caspase-3, which could be decreased by lipid emulsion(P<0.01).Conclusion Bupivacaine could reduce H9c2cells apoptosis.2%LE can inhibit mitochondrialpotential depolarization and decrease Cleaved caspase-3expression all associating withreduction of apoptosis. The apoptosis caused by bupivacaine can sharply reduced by2% lipid emulsion and showed the effect of cardiopretection. |
PDF Full Text Request