Study On Cerebral Protection Of Rats During Deep Hypothermic Circulatory Arrest

Objective To establish a kind of Deep Hypothermic Circulatory Arrest (DHCA)model in rats. Research on the influence of DHCA on rat life signs and neurologicalfunction.And to study respectively the protective effect and mechanism of nimodipinecombined with intermittent perfusion the protecting liquid of of brain on cerebralischemia reperfusion injury in DHCA. Comparison of their brain protection effect.Toprovide reliable and abundant experimental evidence for clinical application ofDHCA Technology.MethodsThe first part:To establish the rat model of cerebral ischemia:30male SD rats, wererandomly divided into experimental group (two vessel occlusion plus hypotension)and control group (no two vessel occlusion plus hypotension).15rats in each group.Blood pressure and heart rate were monitored and compared between the two groupsof rats before cooling, circulatory arrest (21±1)℃and to32℃rewarming.And withLonga’5grades standard evaluation nervous system injury of4H after reperfusion inrat. By HE staining to observe the pathological changes of brain tissue at24h ofreperfusion.The second part:Study on cerebral protection effect of nimodipine during DeepHypothermic Circulatory Arrest: By two vessel occlusion combined with hypotensionto make the rat models of DHCA.96male SD rats of DHCA model were randomlydivided into DHCA group(simple DHCA)and nimodipine group(DHCA+Nimodipine).Each group were divided into ischemia reperfusion0h（T1）,2h（T2）,6h（T3）,12h（T4），24h（T5）and48h（T6） six subgroups，8rats in each group.The contentof S100in serum and brain water content were measured taken in different timepoints around DHCA. By HE staining to observe the pathological changes of brain tissue.The third part:Study on cerebral protection effect of cerebral protection liquidcombined with nimodipine during Deep Hypothermic Circulatory Arrest:60male SDrats were randomly divided into three groups and20rats in each group. Group A:simple DHCA; Group B: DHCA+intermittent perfusion cerebral protectivefluid;Group C:DHCA+intermittent perfusion cerebral protectivefluid+nimodipine.S100protein content of blood taken in reperfusion24h aroundDHCA was measured in each group.By HE staining and TUNEL staining to observeand measure the apoptosis of nerve cell in brain tissue.ResultsThe first part:(1)Mortality of rats in the experimental group was13.3%, control groupno death in rats.(2)When before cooling and rewarming to32℃,no significantdifference between the two groups of blood pressure and heart rate in rats(P﹥0.05).When stopped circulation blood pressure, heart rate and other indicators aresignificantly different (P<0.01).(3) Evaluation of Longa5level neural system injuryat24h after reperfusion, show that there are significant differences(P<0.05). Thescore in the two groups of rats after reperfusion for24h were Level0, no damage tothe nervous system manifestations.(4)The brain tissue of rats in the experimentalgroup appeared obvious pathological changes after24h, and in the control groupshowed no significant pathological changes.The second part:(1)The content of S100in serum and brain water content began toincrease after ischemia reperfusion2h in DHCA group and the nimodipinegroup,reached the peak after ischemia reperfusion24h,began to decrease afterischemia reperfusion48h.Compared with DHCA group,the content of S100in serumwere lower than DHCA group at each time point in Nimodipine group(P<0.05orP<0.01).(2)Brain water content were lower than that in DHCA group from T2toT5(P<0.05or P<0.01).(3)HE staining showed: Two groups of rats brain tissue showedobvious pathological changes after ischemia reperfusion24h.But compared withDHCA group the nimodipine group was significantly reduced.The third part:Cerebral ischemia of rats in the three groups after reperfusion for 24h,compared with the group A,S100protein content of blood and nerve cellapoptosis index were significantly reduced in the group B and the group C(P<0.01).Comparison between group B and group C in the S100protein content of blood andnerve cell apoptosis index,there were statistically significant differences(P<0.01).Conclusions(1)Using the two vessel occlusion and low blood pressure to the preparation of ratDHCA model of cerebral ischemia,is reasonable, feasible, economic. Provides basicconditions and experimental basis for brain protection technology of DHCA.(2)Given nimodipine can significantly reduce brain injury and brain edema. Also caninhibit the apoptosis of cortical neurons. Have a good protective effect on neuronalinjury induced by DHCA.(3)Given the intermittent perfusion oxygenated cerebral protective fluid cansignificantly reduce brain damage. Also can inhibit the apoptosis of hippocampal andcortical neurons.After the joint application of it and nimodipine,cerebral protectiveeffect is better than simple perfusion cerebral protective fluid.