Experimental Study On Mechanism Of Acute Myocardial Injury Following Cardiopulmonary Resuscitation In Dogs

Objective: By virtue of the model that dogs were induced ventricularfibrillation (VF) by electric shock and resuscitated, we observed changes of Na+-K+ATPase and Ca(2+) ATPase activity, Na+, K+, Ca(2+), TNF and ET contents inmyocardium and venous blood and studied their effect on acute myocardial injurypost resuscitation.Methods: Dogs were induced VF by electric shock and resuscitated withstandard open-chest CPR in 10 minutes. ATPase activity, TNF, ET and cationcontents were measured at 10 minutes after VF, 30min, 2h and 4h post-resuscitationrespectively. 32 dogs were randomly divided into 8 groups: the normal control group(n=t); sham control 1, 2, 3 groups (Dogs were weren' t induced VF, the sample weretaken at 30min, 2h, 4h after operation respectively, each group n=4); experimentalgroups including: VF group (n=4) and postresuscitation l, 2, 3 groups (The samplewere taken at 30min, 2h, 4h postresuscitation respectively, each group n=4).ResuIts: All indexs measured among all the control groups were notsignificantiy different.Compared with those of the normal group: â‘ Myocardial Na+-K+ATPase andCa(2+) ATPase activity decreased significanly (P<0.01 vs P<0.05 ) in eachexperimental group. Ca(2+) ATPase activity reached lowest values (P<0.01) at 30minules post resuscitation. Na+-K+ATPase activity reduced to greatest extent(P<0.01 ) at 2 hours after resuscitation of spontaneous circulation (ROSC). Na+,Ca(2+) contents of myocardium increased evidently (all P<0.01 ) and K+ contentsdecreased significantly (P<0.01 ) at 0.5 hour after CPR. Changes of Na+, K+ contentsbegan to restore and Ca(2+)contents reached peak values at 4 hours post-resuscitation.â‘¡ CK-MB activity of blood rose significanly (P<0.05) at 30 minute aller CPRand reached peak values (P<0.01 ) at 4 hours post-resuscitation. The numberanalyzed indicated that there was significanly negative relation (rr-0.6751' P<0.05 )between myocardial Na+-K+ATPase activity and CK-MB of blood activity in normalcontrol grouP and all experimental grouPs. @ Ca2+ATPase activity in myocardialmitochondria decreased significanly (P<0.01 ) and Ca2+ contents increasedsignificantly (P<0.0l ) at 0.5 hour ther CPR. At 4 hours post resuscitation, Ca2+ATPase activity restored normal while Ca2+contents were still higher than those of thenormal group (P<0.01 ). @ Na+-K+ATPase activity of RBC membrane of allexperimental grouPs was lower than that of the normal grOuP. Ca2+ ATPase activitybegan to decrease significanly (P<0.05) at 30 minute aller resuscitation and kepttill 4 hours post ROSC. Na+, Ca2+contents of RBC increased significanly (P<0.05 )while K+ contents cut down evidently (P<0.05 ) in all experimental groups. We stillfound that there was significantly positive correlation(r=0.7350, P<0.0l ) betWeenmyocardial Ca2+ contents and Ca2+ contents of RBC in normal control grouP and allexPerimental grouPs and there was also sighficanly negative correlation (po-0.5323,P<0.0l ) between myocardial Ca2+ contents and Ca2+ATPase activity of RBC.@Myocardial TNF contents increased significantly (P<0.05 ) at 0.5 hour postresuscitation and kept increasing till 4 hours post CPR. ThF levels of blood in allexperimental groups were higher than those in the normal grouP (P<0.0l ) .@Myocardial ET contents increased distinctly (P<0.0l ) at 30 minutes post CPR andlast to 4 hours post CPR. ET contents of blood began to go uP significanly(P<0.0l ) at 0.5 hour and increased to greatest degree at 2 hours post ROSC. Therewas significantly positive relation (r=-0.7138, P<0.0l ) between ET levels of bloodand myocardial Ca2+ contents in normal control grouP and all experimental grouPs.There was also significanly positive relation betWeen ET levels of blood andmyocardial Ca2+ contents (po0.802l, P<0.0l ) in normal control grouP and allexperimental grouPs.The results of all experimental groups' indexs compared with the respondingsham controI groups' were simiIar t...