Effect Of Potassium Chloride On Brain Ischemia Reperfusion Injury Protection During Postresuscitationin Rat With Cardiac Arrest

OBJECTIVE: To determine whether the application of potassium chloride reduce the cerebral ischemia-reperfusion injury of rats or not before cardiopulmonary resuscitation.METHODS: Sprague-Dawley rats were subjected to cardiac arrest by electrical stimulation.Five minutes after onset of stimulation,rats with cardiac arrest were divided into 3 groups.Then rats in each group,respectively,received normal saline with dosage of 3.2 ml/kg body weight(NS group,n=16),1.25%potassium chloride solution with dosage of 3.2 ml/kg body weight(KCL1 group,n=16)and 2.5% potassium chloride solution with dosage of 3.2 ml/kg body weight(KCL2 group,n=16)before conventional cardiopulmonary resuscitation.Serum potassium concentration was measured at baseline,2 min and 10 min after restoration of spontaneous circulation respectively.Neurological deficit scores was evaluated at 24 hours after ROSC in three groups.Rats in each groups were equally divided in to 2 sub-groups.The serum contents of neuron specific enolase and calcium content in brain tissue of 24 h were measured byenzyme-linked-immune sorbent assay and calcium assay kit respectively in the first subgroup.In the second sub-group.The morphological changes of neuron and apoptosis of neuron by TdT mediated dUTP nick end labeling(TUNEL)fluorescence were tested.RESULTS: The electrical stimulation duration,ROSC time,basis of potassium concentration,ratio of ROSC and survival rate of 24 h were no significant difference in three groups of rats(P>0.05).The potassium concentration at two minute after ROSC in KCL1 group(7.34±0.40)mmol/L and KCL2 group(8.00±0.91)mmol/L were significantly higher compared to NS group(5.27±0.44)mmol/L(P<0.01).The potassium concentration at ten minute after ROSC of KCL2 group(5.19 ± 1.04)mmol/L was still significantly higher(P<0.05),while the KCL1 group(4.27±0.86)mmol/L show a mild increased trend without statistical difference(P>0.05)compared with the NS group(3.68 ±0.43)mmol/L.NDS has no obvious difference(P>0.05)in three groups.Serum NSE content of 24 h in the KCL1 group(4.06±0.11)ng/ml and KCL2 group(3.39±0.70 ng/ml)were significantly decreased than the NS group(5.45 ±0.51)ng/ml(P<0.05).At 24 h,brain tissue calcium content tendency in KCL1 group and KCL2 group were respectively(0.62±0.09)mmol/gprot and(0.52±0.11)mmol/gprot,compared to NS group(0.59±0.08)mmol/gprot,there is no significant difference(P>0.05).HE dyeing observation of cell morphology change is neat in KCL1 group and KCL2 group is different with disordered arrangement of NS group of cells.The apoptosis index of 24 h of hippocampal area in KCL1 group and KCL2 were(14.75±5.12)and(12.25±3.09),which are less than NS group(25.75±7.13)significantly(P<0.05).Apoptosis index of cerebral cortex in KCL1 group and KCL2 group were(13.25±4.1)and(9.25±2.7),which were lower than(24.25±8.5)in NS group(P<0.05).CONCLUSION: Application of potassium chloride before CPR can reduce IRI of rat brain,while the mechanism dose not relate to calcium overload.Further study on its mechanism is still needed.