The Involvement Of Thioredoxin In Myocardial Ischemia Reperfusion Injury With Stress Hyperglycemia In Rats

Objective By analyzing the expression of Trx at different times andobserving the different effects of SHG on ischemia(I) and reperfusion(R)periods during MIRI, to investigate the involvement of thioredoxin(Trx) inmyocardial injury aggravated by stress hyperglycemia(SHG) in differentperiods of myocardial ischemia/reperfusion injury(MIRI) in rats.Methods and materials50adult SD rats were randomly divided intofive groups,of which sham group and high glucose group were only exposedwithout left anterior descending coronary artery(LAD) occlusion,and the restgroups that underwent ligation were subjected to30minutes of coronaryocclusion and followed by3hours of reperfusion to make myocardial ischemiareperfusion models. The experiment groups were as follows:(1) sham group(SHAM);(2) the high glucose group (HG):500g/L high glucose wasintravenously infused for3.5h;(3)the normal saline control group(CON):normal saline was given for3.5h;(4)the ischemia of high glucosegroup(HGI):500g/L high glucose1ml was injected one time, and then acontinuous intravenous pump was given until the end of I,normal saline wasgiven during R;(5)the reperfusion of high glucose group (HGR):normal salinewas infusion during I,then500g/L high glucose was given until the end of R.We monitored the blood glucose levels at different times of theexperiment:before I,25min after I,1.5h after R,3h of R, respectively.After R,serum lactate dehydrogenase(LDH) levels were determined.Evans blue stainingmethod to measure the myocardial infarct size(IS), the expression of Trx wasmeasured by Western Blot． Results1. After intravenously infusing of high glucose, serum LDH levels did notchange significantly, but when the body was suffered from MIRI, serum LDHlevels were significantly increased, the serum LDH level in CON group, HGIgroup, HGRgroup were were(2270.37±192.43) mmol/L,(2929.38±203.94)mmol/L,(2410.94±174.35) mmol/L respectively(P<0.05)2. Compared with the SHAM group, the serum LDH level of CON groupwas2.65times (2270.37±192.43VS857.86±28.06, P<0.05),and the HGIgroup,HGRgroup were3.41times (2929.38±203.94VS857.86±28.06, P <0.05) and2.81times(2410.94±174.35VS857.86±28.06, P<0.05),respectively.3. Compared with the CON group, the serum LDH level of HGIgroup was1.29times(2929.38±203.94VS2270.37±192.43, P<0.05),while HGRgroupwas1.06times(2410.94±174.35VS2270.37±192.43, P>0.05).4. There were significant myocardial infarct size in rats with myocardialischemia-reperfusion. Compared with the CON group, the HGIgroup wassignificantly expanded (46.93±3.52)%VS (36.53±3.06)%,(P<0.05).5. The Trx expression levels in rats with myocardial ischemia/reperfusioninjury were significantly higher than SHAM group and HG group (P>0.05).Compared with CON group, HGIgroup and HGRgroup showed a significantlyhigher in Trx level(P<0.05),and there were significant difference between HGIgroup and HGRgroup in Trx level (P<0.05).Conclusion Stress hyperglycemia during ischemia can aggravatemyocardial ischemia/reperfusion injury in rats,and at the same time causeincreased expression of Trx which may be involved into the process of myocardialanti-oxidative damage.