The Protective Effect Of Small Intestine's Ischemia And Hemodilution To Myocardial Ischemic And Reperfusion Injury In Rabbits

Objective: The objective of our experiment is to observe theprotective effects of preconditioning with small intestine ischemia andnormovolemic hemodilution upon reperfusion injury.Methods: Adult New Zealand rabbits grouped in 3 groups randomly,each of the group have 6 rabbits. GroupⅠ: ischemic-reperfusion;groupⅡ: preconditioning with a 15-min small intestine occlusion; groupⅢ: preconditioning with both a 15-min small intestine occlusion andnormovolemic hemodilution. Heart rate and blood pressure weremonitered during experimental session. CK, CK-MB, LDH and CTnIwere measured after operation completed. The myocardial area at the riskof Ischemia and infarct size was also measured and the stuct of cell andinferior-cell of myocardium was observed under the electron microscope.Results: 1. There were no significant difference among all thegroups about the general average of the basic blood pressure and heartrate. The blood pressure and heart rate is obviously lower than thegroupⅠwhen the arteria intestinales have been deligated (P＜0.05) andslightly higher than before after hemodilution (P＞0.05). 2. The rise aboutCK, CK-MB and LDH at groupsⅡandⅢare obviously lower than thegroupⅠ(P＜0.05), and there is no significant difference between thegroupⅡand groupⅢ(P＞0.05). 3,The area of ischemic area(AR) has no significant difference among all of the groups (P＞0.05), and thegeneral average of it is 55.2％±1.4％. The average infarct size of groupⅡis 21.3±0.7％and groupⅢis 20.9±1.1％, which are both obviouslysmaller than the IR group(P＜0.05), and there is no significant differencebetween groupⅡand groupⅢ(P＞0.05). 4. The results of the electronmicroscope: the necrolysis of muscle fiber and extensive vacuolization ofmitochondria can be observed in groupⅠ. The cell damage to groupⅡand groupⅢis obviously slighter than groupⅠ, and their muscle fiber isalmostly normal with a few vacuolizated mitochondria.conclusion: 1. Preconditioning with small intestine ischemia canreduce the infarct size during the long time ischemia and reperfusion, andagainst the injury of IR and inhibit the rise of myocardium enzyme. 2.Normovolemic hemodilution does not weaken the protective effects ofpreconditioning with small intestine ischemia upon reperfusion injury ofmyocardium.