Experimental Study Of Hepatocyte Injury After Cardiopulmonary Resuscitation In Rats

Objective: To investigate the mechanism of hepatocyte injury and effect of astragalosides after cardiopulmonary resuscitation(CPR) in rats. Methods:Cardiac arrest was induced by asphyxiation(succinylcholine) and ice-cold 0.5M KCL in rats and resuscitation efforts were begun five minutes after arrest. 42 male Sprague Dawley rats were randomly divided into 7 groups : sham (control )group; rats after cardiopulmonary resuscitation were allowed to reperfuse spontaneously for 3 hours group, 6hours group, 12hours group and 24hours group; 6hours astragalosides group and 24hours astragalosides group; n=6, per group. Alanine aminotransferase (ALT), Aspartate aminotransferase(AST), levels of tumor necrosis factor α ( TNF- α ) and interleukin-1 β (IL-1β) in blood serum of all groups were measured. The temporospatial cellular reactions were assessed by terminal deoxynucleotidyltransferase-mediated dutp-FITC nick endlabeling(TUNEL) and transmission electron microscope(TEM). Bcl-2, Bax and NF- k B protein expression were studied using immunocytochemistry in all groups. Result: ALT and AST levels in 3 hour group were 392.1u/L±91.8u/L and 367.5u/L±226.0u/L , markedly higher compared to other cardiopulmonary resuscitation groups. We find that the levels of TNF- α and IL-1 β in all groups after cardiopulmonary resuscitation were higher than in control group during the study period (P<0.05), and them in astragalosides groups were lower than in groups after cardiopulmonary resuscitation. TUNEL - positive cells could be observed in the liver of all groups, TUNEL - positive cells in control group was 3.12%±0. 56%; 35.74%±2. 35%, 56.63%±3. 41%, 44.58%±2. 98%, 47.53%±2. 15% at 3 hour, 6hour, 12hour and 24hour group after cardiopulmonary resuscitation;and they were 38.26% ±3. 02%, 28.56%±2. 31% at 6hour and 24hour astragalosides group.Hepatocyte apoptosis was found in all groups with transmission electron microscope .Few Bcl-2 express protein was found in 3 hour group after cardiopulmonary resuscitation and it continuous to increase; Bcl-2- positive cells were 57.79%±8. 35%, 80.32%± 9. 41% at 6 hour, 24hour post-resuscitation group; and they were lower than Bcl-2 protein expression at 6hour , 24hour astragalosides group(P<0.05).Bax protein expression was higher than Bcl-2 in 3hours, 6hours, 12hours groups after resuscitation, led to Bcl-2/Bax ratio imbalance. NF- K B protein expression was 6.17%±9. 41% in sham group; it rose to 69.73%±7. 53% at 3hour after resuscitation; there were 56.23% ±9.41% , 67.70% ±12.52% and 29.8% ±3. 56% NF- K B - positive cells in liver at 6hour, 12hour and 24hour after resuscitation; and it in astragalosides groups was higher than in groups after resuscitation.Conclusion: Hepatocyte undergo damage after CPR in rats.Apoptosis is one mechanism of hepatocyte injury after CPR, the results of this study demonstrate that Bcl-2/Bax ratio imbalance, NF-k B expression are responsible for the hepatocyte apoptosis. astragalosides is protective against hepatocyte injury after CPR in rats.