Evaluation Of Hepatic Funtion By ¹³C-methacetin Breath Test In Rats With Alcohol-induced Acute Liver Injury

Objective: To investigate the characteristics of ¹³C-methacetin breath test (¹³C -MBT) as a tool to monitor hepatic function of rats with acute liver injury induced by alcohol, and the relations between these results with those of hepatic pathological changes and biochemical tests of the liver function and the expression of cytochrome P45O1A2(CYP1A2) in liver tissues.Methods: Gavage of alcohol was adopted to duplicate rats acute liver injury model. Thirty-two healthy female Wistar rats, weighing 180-220g, were randomly divided into four groups, normal control group,acute liver injury groups with different alcohol volume 4g/kg,6g/kg,8g/kg.Infrared isotope spectrometry (IRIS) was used to design the detect program and the method of rats ¹³C -MBT. And after ¹³C-methacetin administered by gavage,thirty-one breath samples were taken and measured every two minutes within 60 minutes.The changes of the three parameters of the duration to peak (T) of ¹³CO₂ DOB (delta over baseline) curve, ¹³CO₂ maximum metabolisation Velocity (MVmax) and ¹³CO₂ cumulative dose within 60 minutes (CUM60) were determined. The hepatic pathological changes and biochemical tests of the liver function were also determined. Moreover, correlation between the parameters of ¹³C -MBT and these indexes of hepatic pathological changes and biochemical tests were analyzed. The expression of cytochrome P450 1A2 (CYP1A2) in liver tissues was observed by immunohistochemistry technique.Results: The parameter of ¹³C -MBT T significantly discriminated between controls (27.63±1.69min) and acute liver injury rats of 4g/kg (16.63±1.77min),6g/kg (12.75±2.05min),8g/kg (10.88±2.23min)(F=118.63,p<0.001). MVmax existed statistically significant differences between rats of control group (36.11±3.09%) and all acute liver injury groups (4g/kg group 49.01±2.79%,6g/kg group 61.63±3.75%,8g/kg group 75.90±3.79%, F=203.26,p<0.001). The same results were obtained by compared CUM60 between four groups (control group 33.26±3.44%,4g/kg group 47.40±3.07%,6g/kg group 59.34±2.04%,8g/kg group 70.16±2.07%,F=271.32,p<0.001). The parameters of 13C -MBT T of acute liver injury rats were significantly correlated to liver index, hepatic pathological grades and aspartate aminotransferase (AST), total bilirubin(TBIL), total bile acid (TBA) and AKP(p all less than 0.05).MVmax and CUM60 of acute liver injury rats were significantly correlated to liver index, hepatic pathological grades and aspartate aminotransferase (AST), total bilirubin(TBIL),γ-glutamyl transferase(GGT), total bile acid (TBA) and AKP(p all less than 0.05).The expression of CYP1A2 in rats liver tissues of acute liver injury was increased under the observation by light microscope.Conclusions: The parameters of ¹³C -MBT can sensitively discriminate normal controls and acute liver injury rats as a tool to evaluating liver function;The parameters of ¹³C -MBT MVmax and CUM60 vary with the degrees of liver injury:the latter increase, the former increases, so it can reflect the degrees of hepatic pathological alteration of acute liver injury;T,MVmax and CUM60 had changed when the liver function was slightly injuried, while indexes of biochemical test did not change, ¹³C -MBT can earlier make diagnosis in acute alcoholic liver injury than biochemical test.