Myocardial Ischemia-reperfusion In Diabetic Rats Research Articles

ACTIVATION OF KLOTHO/SIRT1 SIGNALING PATHWAY ATTENUATES MYOCARDIAL ISCHEMIA REPERFUSION INJURY IN DIABETIC RATS.

Diabetes and myocardial ischemia reperfusion (MIR) injury are characterized by oxidative stress, inflammation, autophagy disorders, and cardiac contractile dysfunction. Klotho and SIRT1 regulate the level of oxidative stress to participate in the regulation of many physiological functions such as cell survival, aging, apoptosis, autophagy, mitochondrial biogenesis, and inflammation. We hypothesized that the activation of Klotho/SIRT1 signaling pathway could attenuate MIR in diabetic rats. Type 1 diabetes and MIR injury model were established to examine this hypothesis in vivo . Primary rat cardiomyocytes and H9c2 cells were exposed to high glucose conditions and hypoxia/reoxygenation (H/R) insult in vitro . Hemodynamic parameters of heart function, myocardial infarct size, oxidative stress, markers of MIR injury or cell viability, and the mRNA and protein expression of Klotho and SIRT1 were measured. There was lower expression of Klotho and SIRT1 in diabetic MIR hearts than in nondiabetic rats, as well as significantly increased oxidative stress levels and decreased autophagy levels. Recombinant Klotho (rKlotho) protein and the SIRT1 agonist SRT1720 could significantly attenuate MIR injury in diabetes by activating Klotho/SIRT1 signaling pathway to reduce oxidative stress and restore autophagy levels. These findings suggest that the Klotho/SIRT1 pathway plays an important role in MIR injury in diabetic rats, and rKlotho protein and agonist SRT1720 have therapeutic potential for alleviating diabetic myocardial IR injury by activating Klotho/SIRT1 to reduce oxidative stress and restore autophagy levels.

Rev-erbs agonist SR9009 alleviates ischemia-reperfusion injury by heightening endogenous cardioprotection at onset of type-2 diabetes in rats: Down-regulating ferritinophagy/ferroptosis signaling

The complex progression of type-2 diabetes (T2DM) results in inconsistent findings on myocardial susceptibility to ischemia-reperfusion (IR). IR injuries in multiple organs interconnect with ferroptosis. Targeting Rev-erbs might limit ferroptosis, with increasing attention turning to the application of circadian medicine against IR injuries. However, whether the Rev-erbs agonist SR9009 could mitigate diabetic IR injury remains unknown. Here, we investigated the susceptibility to IR at onset of T2DM in rats and its potential association between SR9009 and ferritinophagy/ferroptosis signaling. Onset of T2DM model was induced with a high-fat diet and the intraperitoneal injection of a low dose of streptozotocin. Myocardial IR model was established as well. Rats’ general characteristics, cardiac function, glycolipid profiles, serum biochemistry, apoptosis index (AI) and morphological histology were observed and analyzed. Western blot and immunofluorescence (IF) were employed to evaluate the expression of ferritinophagy/ferroptosis signaling and its co-localization. Glycolipid profiles and cardiac diastolic function were significantly impaired in diabetic rats. CK-MB, AI levels and ferritinophagy/ferroptosis-related proteins expression decreased towards myocardial IR in diabetic rats compared to non-diabetic rats’. The ferroptosis inducer Erastin up-regulated SOD, MDA, and AI levels, as well as the expression of ferritinophagy/ferroptosis-related proteins in diabetic rats towards IR. Treatment with SR9009 down-regulated the degree of myocardial injury and ferritinophagy/ferroptosis-related proteins expression compared to diabetic rats treated with or without Erastin. Onset of T2DM activated endogenous cardioprotection against the susceptibility to myocardial IR injury, and SR9009 exogenously enhanced this endogenous mechanism and alleviated myocardial IR injury at onset of T2DM by down-regulating ferritinophagy/ferroptosis signaling.

Role of HDAC3 in renal injury induced by myocardial ischemia-reperfusion in diabetic rats

Objective To evaluate the role of histone deacetylase 3 (HDAC3) in renal injury induced by myocardial ischemia-reperfusion (I/R) in diabetic rats. Methods SPF healthy adult male Sprague-Dawley rats, weighing 210-220 g, were used in this study.Diabetes mellitus was induced by intraperitoneal injection of 1% streptozotocin 60 mg/kg.Eighteen diabetic rats were divided into 3 groups (n=6 each) using a random number table method: sham operation group (group S), group I/R and HDAC3 inhibitor RGFP966 group (RG). The myocardial I/R model was established by ligation of the left anterior descending coronary artery for 30 min followed by 120-min reperfusion.RGFP966 10 mg/kg was intraperitoneally injected at 1 h before myocardial ischemia in group RG.The right internal carotid artery was isolated at 120 min of reperfusion for measurement of serum lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), creatinine (Cr) and urea nitrogen concentrations.Renal tissues were obtained for examination of the pathological changes and for determination of the expression of HDAC3, silent information regulator 1 (SIRT1) and interleukin-1β (IL-1β). The damage to the renal tubules was scored. Results Compared with S group, the serum LDH, CK-MB, Cr and urea nitrogen concentrations and renal tubular damage score were significantly increased, the expression of HDAC3 and IL-1β was up-regulated, and the expression of SIRT1 was down-regulated in group I/R (P<0.05). Compared with group I/R, the serum LDH, CK-MB, Cr and urea nitrogen concentrations and renal tubular damage score were significantly decreased, the expression of HDAC3 and IL-1β was down-regulated, and the expression of SIRT1 was up-regulated in group RG (P<0.05). Conclusion Up-regulated expression of HDAC3 is involved in renal injury induced by myocardial I/R in diabetic rats. Key words: Histone deacetylases; Diabetes mellitus; Myocardial reperfusion injury; Acute kidney injury

Role of NLRP3 inflammasome in pyroptosis during myocardial ischemia-reperfusion in diabetic rats

Objective To evaluate the role of NOD-like receptor 3 (NLRP3) inflammasome in pyroptosis during myocardial ischemia-reperfusion (I/R) in diabetic rats. Methods SPF male Sprague-Dawley rats, aged 6-8 weeks, weighing 210-230 g, were studied.Type 1 diabetes mellitus (DM) was induced by intraperitoneal injection of 1% streptozotocin 60 mg/kg.Forty-two rats with type 1 DM were divided into 4 groups using a random number table method: sham operation group (DS group, n=6), myocardial I/R group (DI/R group, n=12), myocardial I/R plus caspase-1 inhibitor Ac-YVAD-CMK group (DI/R+ Ac group, n=12) and myocardial I/R plus NLRP3 inhibitor BAY11-7082 group (DI/R+ BAY group, n=12). Eighteen healthy adult male Sprague-Dawley rats were selected and randomly divided into sham operation group (group S, n=6) and myocardial I/R group (group I/R, n=12). Myocardial I/R was induced by 30 min occlusion of the left anterior descending branch of the coronary artery followed by 120 min reperfusion at 8 weeks after successful establishment of the type 1 DM model.Ac-YVAD-CMK 1.5 mg/kg and BAY11-7082 5 mg/kg were intraperitoneally injected at 10 min before reperfusion in DI/R+ Ac group and DI/R+ BAY group, respectively.At the end of reperfusion, the myocardial infarct size was measured using TTC staining, the activities of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) in serum were detected by enzyme-linked immunosorbent assay, the ultrastructure of myocardium was observed by transmission electron microscopy, and the expression of NLRP3, pro-caspase-1, caspase-1, apoptosis-associated speck-like protein containing CARD (ASC) and interleukin-1 (IL-1β) in myocardial tissues was detected by Western blot. Results Compared with group S or group DS, the activities of serum CK-MB and LDH were significantly increased, and the expression of NLRP3, pro-caspase-1, caspase-1, ASC and IL-1β was down-regulated in I/R and DI/R groups (P<0.05). Compared with group DI/R, the percentage of myocardial infarct size and activities of serum CK-MB and LDH were significantly decreased, and the expression of NLRP3, pro-caspase-1, caspase-1, ASC and IL-1β was down-regulated in group I/R, the percentage of myocardial infarct size and activities of serum CK-MB and LDH were significantly decreased, and the expression of pro-caspase-1, ASC and IL-1β was down-regulated in group DI/R+ Ac, and the percentage of myocardial infarct size and activities of serum CK-MB and LDH were significantly decreased, and the expression of NLRP3, pro-caspase-1, caspase-1, ASC and IL-1β was down-regulated (P<0.05), and the pathological changes of myocardium were significantly attenuated in group DI/R+ BAY. Conclusion The mechanism of pyroptosis during myocardial I/R may be related to the activation of NLRP3 inflammasome in diabetic rats. Key words: Diabetes mellitus; Myocardial reperfusion injury; Pyroptosis; NOD-like receptor protein 3

The Roles of Autophagy in Acute Lung Injury Induced by Myocardial Ischemia Reperfusion in Diabetic Rats

Patients with diabetes are vulnerable to myocardial ischemia reperfusion (IR) injury, which may also induce acute lung injury (ALI) due to overaccumulation of reactive oxygen species (ROS) and inflammation cytokine in circulation. Despite autophagy plays a significant role in diabetes and pulmonary IR injury, the role of autophagy in ALI secondary to myocardial IR in diabetes remains largely elusive. We aimed to investigate pulmonary autophagy status and its roles in oxidative stress and inflammation reaction in lung tissues from diabetic rats subjected to myocardial IR. Control or diabetic rats were either treated with or without autophagy inducer rapamycin (Rap) or autophagy inhibitor 3-methyladenine (3-MA) before myocardial IR, which was achieved by occluding the left anterior descending coronary artery for 30 min and followed by reperfusion for 120 min. Diabetic rats subjected to myocardial IR showed more serious ALI with higher lung injury score and WET/DRY ratio and lower PaO2 as compared with control rats, accompanied with impaired autophagy indicated by reduced LC-3II/LC-3I ratio and Beclin-1 expression, decreased superoxide dismutase (SOD) activity, and increased 15-F2t-Isoprostane formation in lung tissues, as well as increased levels of leukocyte count and proinflammatory cytokines in BAL fluid. Improving autophagy with Rap significantly attenuated all these changes, but the autophagy inhibitor 3-MA exhibited adverse or opposite effects as Rap. In conclusion, diabetic lungs are more vulnerable to myocardial IR, which are involved in impaired autophagy. Improving autophagy could attenuate ALI induced by myocardial IR in diabetic rats, possibly through inhibiting inflammatory reaction and oxidative stress.

Mechanism of myocardial ischemia/reperfusion-induced acute kidney injury through DJ-1/Nrf2 pathway in diabetic rats.

The objective of the present study was to investigate acute kidney injury (AKI) induced by myocardial ischemia/reperfusion (MIR) in diabetic rats and elucidate its underlying mechanism. A rat model of MIR was established by left anterior descending coronary artery occlusion for 30 min, followed by reperfusion for 2 h. Rats were randomly divided into four groups: i) Sham group, ii) sham + MIR group, iii) diabetic group and iv) diabetes + MIR group. Myocardial injury was detected by plasma creatine kinase isoenzyme MB and lactate dehydrogenase assays. AKI induced by MIR in diabetic rats was characterized by increases in cystatin C and β2-microglobulin levels. Oxidative stress injury was accompanied by an increase of malondialdehyde levels and a decrease of total antioxidative capacity in the renal tissues. Immunohistochemistry and western blot analysis demonstrated that the expression of DJ-1 and nuclear factor erythroid 2-related factor 2 (Nrf2) were significantly increased in the diabetes + MIR group compared with that in the sham + MIR and diabetic groups. Taken together, these results suggested that AKI induced by MIR in diabetic rats may be associated with activation of the DJ-1/Nrf2 pathway.

Effects of N-acetylcysteine on caveolin-3 expression during myocardial ischemia-reperfusion in diabetic rats

Objective To evaluate the effects of N-acetycysteine on the expression of caveolin-3 (Cav-3) during myocardial ischemia-reperfusion (I/R) in diabetic rats. Methods Twenty-four pathogen-free healthy adult male Sprague-Dawley rats, weighing 230-270 g, were divided into 3 groups (n=8 each) using a random number table: myocardial I/R group (group I/R), diabetes mellitus plus myocardial I/R group (group D) and N-acetycysteine group (group NAC). Diabetes mellitus was induced by injection of streptozotocin 60 mg/kg via the tail vein and confirmed by blood glucose ≥16.7 mmol/L 3 days later.At 1 week after successful establishment of the model, N-acetycysteine 1.5 g·kg-1·d-1 was injected through a gastric tube into stomach for 4 consecutive weeks in group NAC, and the equal volume of normal saline was given for 4 consecutive weeks in I/R and D groups.Myocardial I/R was then induced by 30 min ligation of the left anterior descending branch of the coronary artery followed by 2 h of reperfusion.At the end of reperfusion, the myocardial infarct size was determined by triphenyl tetrazolium chloride staining, the levels of serum creatine kinase-MB (CK-MB) and 15-F2t-Isoprostane were measured by enzyme-linked immunosorbent assay, and the expression of myocardial Cav-3, Akt, phosphor-Akt (p-Akt), endothelial nitric oxide synthase (eNOS) and phosphor-eNOS (p-eNOS) was detected by Western blot. Results Compared with group I/R, the myocardial infarct size and levels of serum CK-MB and 15-F2t-Isoprostane were significantly increased, and the myocardial Cav-3, p-Akt and p-eNOS expression and NO level were decreased in group D (P<0.05). Compared with group D, the myocardial infarct size and levels of serum CK-MB and 15-F2t-Isoprostane were significantly decreased, and the myocardial Cav-3, p-Akt and p-eNOS expression and NO level were increased in group NAC (P<0.05). Conclusion N-acetycystein can activate Akt/eNOS/NO signaling pathway through up-regulating myocardial Cav-3 expression, thus reducing myocardial I/R injury in diabetic rats. Key words: N-acetylcysteine; Diabetes mellitus; Myocardial reperfusion injury; Coated pits, cell-membrane

Role of JAK2/STAT3 signaling pathway in brain injury induced by myocardial ischemia-reperfusion in diabetic rats

Objective To evaluate the effects of Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) signaling pathway on the brain injury induced by myocardial ischemia-reperfusion (I/R) in diabetic rats. Methods Pathogen-free male Sprague-Dawley rats, weighing 200-220 g, were used in this study.Diabetes mellitus was induced by intraperitoneal 1% streptozotocin 60 mg/kg and confirmed by blood glucose level ≥16.7 mmol/L 3 days later.Twenty-four rats with diabetes mellitus were randomly allocated into 3 groups (n=8 each) using a random number table: sham operation group (group S), I/R group, and myocardial I/R + AG490 (JAK inhibitor) group (group IA). Myocardial I/R was induced by occlusion of the anterior descending branch of the left coronary artery for 30 min, followed by 120 min of reperfusion in the rats anesthetized with pentobarbital sodium.AG490 3 mg/kg was injected intravenously at 20 min before reperfusion in group IA.The rats were sacrificed at 120 min of reperfusion, and the brains were removed for determination of caspase-3 and nuclear factor kappa B (NF-κB) activities (using colorimetric method), cell apoptosis (by TUNEL), and expression of interleukin-1 (IL-1), IL-6, IL-8, Bax, Bcl-2, cytochrome C (Cyt c), phosphorylated JAK2 (p-JAK2), and phosphorylated STAT3 (p-STAT3) (by Western blot). Apoptosis index was calculated. Results Compared with group S, the expression of Bax, Cyt c, IL-1, IL-6, IL-8, p-JAK2 and p-STAT3 was significantly up-regulated, the expression of Bcl-2 was down-regulated, and NF-κB and caspase-3 activities and apoptosis index were increased in I/R and IA groups (P<0.05). Compared with group I/R, the expression of Bax, Cyt c, IL-1, IL-6, IL-8, p-JAK2 and p-STAT3 was significantly down-regulated, the expression of Bcl-2 was up-regulated, and NF-κB and caspase-3 activities and apoptosis index were decreased in group IA (P<0.05). Conclusion Inflammatory responses mediated by JAK2/STAT3 signaling pathway are involved in the brain injury induced by myocardial I/R in diabetic rats. Key words: Janus kinase 2; STAT3 transcription factor; Diabetes mellitus; Myocardial reperfusion injury; Brain injuries

Effect of ischemic postconditioning on brain injury induced by myocardial ischemia-reperfusion in diabetic rats

Objective To evaluate the effects of ischemic postconditioning on brain injury induced by myocardial ischemia-reperfusion (I/R) in diabetic rats.Methods Diabetes mellitus was induced by intraperitoneal streptozotocin 60 mg/kg and confirmed by blood glucose level ＞ 16.7 mmol/L.Thirty male Sprague-Dawley rats,weighing 220-280 g,in which diabetes mellitus was successfully induced,were randomly allocated into 3 groups (n =10 each) using a random number table:group sham operation (group S),group I/R and group ischemic postconditioning (group P).Myocardial I/R was induced by occlusion of the anterior descending branch of the left coronary artery in I/R and P groups.Group P received 3 cycles of 10 s reperfusion followed by 10 s ischemia at the end of myocardial ischemia.The rats were sacrificed at 120 min of reperfusion and the brains were removed for microscopic examination and for determination of cell apoptosis (by TUNEL) and expression of interleukin-6 (IL-6),IL-8,IL-10,glycogen synthase kinase-3 beta (GSK-3β) and phosphorylated GSK-3β (pGSK-3β) (by immuno-histochemistry).Apoptotic index was calculated.Results Compared with group S,apoptotic index was significantly increased,IL-6 and IL-8 expression was up-regulated,and IL-10 and pGSK-3β expression was downregulated in I/R and P groups (P ＜ 0.01).Compared with group I/R,apoptotic index was significantly decreased,IL-6 and IL-8 expression was down-regulated,and IL-10 and pGSK-3β expression was up-regulated in group P (P＜0.01).There was no significant difference in GSK-3β expression among the 3 groups (P ＞ 0.05).The pathologic changes were significantly attenuated in group P as compared with group I/R.Conclusion Ischemic postconditioning can attenuate brain injury induced by myocardial I/R in diabetic rats,and inhition of activity of GSK-3β may be involved in the mechanism. Key words: Diabetes mellitus; Myocardial reperfusion injury; Brain injuries; Ischemic postconditioning

Changes in expression of DJ-1 protein during myocardial ischemia-reperfusion in diabetic rats

Objective To evaluate the changes in the expression of DJ-1 protein during myocardial ischemia-reperfusion (I/R) in diabetic rats.Methods Fifty male Sprague-Dawley rats,weighing 220-280 g,were used in this study.Type 1 diabetes mellitus was induced by intraperitoneal streptozotocin 65 mg/kg and confirmed by fasting blood glucose ＞ 16.7 mmol/L.Forty animals with type 1 diabetes mellitus were randomly divided into 3 groups:diabetes group (group D,n =10),diabetic sham operation group (group DS,n =15) and diabetic I/R group (group DIR,n =15).Another 10 non-diabetic rats in which citrate buffer 6 ml/kg was injected intraperitoneally were served as control group (group C).Myocardial I/R was produced by occlusion of the anterior descending branch of left coronary artery for 30 min followed by 120 min reperfusion in group I/R.At 120 min of reperfusion,5 rats were sacrificed and myocardial specimens were c(on)tained for determination of infarct size in groups DS and DIR,and 10 rats were sacrificed and myocardial specimens were obtained for microscopic examination and for determination of cell apoptosis,malondialdehyde (MDA) content,superoxide dismutase (SOD) activity and expression of DJ-1 and phosphatase and tensin homologue (PTEN) protein.Apoptotic index (AI) was calculated.Linear correlation between the expression of DJ-1 protein and MDA content,SOD activity,AI and expression of PTEN protein was analyzed.Results Compared with group DS,the myocardial infract size was significantly increased in group DIR (P ＜ 0.05).Compared with group C,MDA content and AI were significantly increased,SOD activity was decreased,the expression of DJ-1 was down-regulated,and the expression of PTEN protein was up-regulated in groups D,DS and DIR (P ＜ 0.05).Compared with groups D and DS,MDA content and AI were significantly increased,SOD activity was decreased,the expression of DJ-1 was down-regulated,and the expression of PTEN protein was up-regulated in group DIR (P ＜ 0.05).There was no significant difference in the parameters mentioned above between groups D and DS (P ＞ 0.05).There was linear correlation between the expression of DJ-1 protein and MDA content,SOD activity,AI and expression of PTEN protein and the correlation coefficients (r) were-0.734,0.593,-0.818,and-0.812 in turn.Conclusion Down-regulation of DJ-1 protein expression is involved in myocardial I/R injury in diabetic rats via decreasing anti-oxidative stress responses and upregulating PTEN protein expression. Key words: Intracellular signaling peptides and proteins; Myocardial reperfusion injury; Diabetes mellitus

The protective role of hydrogen sulfide in myocardial ischemia–reperfusion-induced injury in diabetic rats

BackgroundHydrogen sulfide (H2S) displays anti-inflammatory and cytoprotective activities to attenuate myocardial ischemia–reperfusion (MIR)-induced injury, but its role in MIR in diabetics is not known. This study was undertaken to investigate whether H2S plays a protective role in MIR in diabetic rats. MethodsDiabetes was induced by streptozocin in Wistar rats, which were subjected to myocardial ischemia by blocking the left circumflex artery for 30min, followed by 2h reperfusion. dl-propargylglycine (PAG) and sodium hydrosulfide (NaHS) were administered to the rats to investigate their effects on severity of MIR-induced injury. ResultsDiabetic rats had smaller myocardial infarct sizes and higher serum levels of H2S (both P<0.05) than non-diabetics when they underwent MIR. MIR significantly increased the serum level of H2S (49.5±7.1μM), H2S-synthesizing activity (7.4±1.6nmol/mg) and the myocardial infarct size (44.0±7.2%), compared with sham-operated diabetic rats (21.7±2.1μM, 0.15±0.4nmol/mg and 1.2±0.4%, respectively). Administration of NaHS increased the H2S level (65.8±6.9μM) and had little effect on H2S production activity (6.5±2.2nmol/mg), while PAG reduced both the H2S level (29.2±5.0μM) and H2S-synthesizing activity (2.2±1.8nmol/mg). NaHS significantly reduced the myocardial infarct size (31.2±4.7%), inhibited the production of lipid peroxidation, MPO activity, and cell apoptosis, and downregulated expression of caspase-3, Fas, FasL, and TNF-α, which had been elevated by MIR, while PAG further increased the myocardial infarct size (58.3±5.9%), and displayed opposite effects. ConclusionsThe study indicates that H2S may play a protective role in MIR-induced myocardial injury in diabetics by its anti-apoptotic, anti-oxidative and anti-inflammatory activities.

Ginsenoside Rb1 Preconditioning Enhances eNOS Expression and Attenuates Myocardial Ischemia/Reperfusion Injury in Diabetic Rats

Diabetes mellitus is associated with decreased NO bioavailability in the myocardium. Ginsenoside Rb1 has been shown to confer cardioprotection against ischemia reperfusion injury. The aim of this study was to investigate whether Ginsenoside Rb1 exerts cardioprotective effects during myocardial ischemia-reperfusion in diabetic rats and whether this effect is related to increase the production of NO via enhancing eNOS expression in the myocardium. The myocardial I/R injury were induced by occluding the left anterior descending artery for 30 min followed by 120 min reperfusion. An eNOS inhibitor L-NAME or Rb1 were respectively administered 25 min or 10 min before inducing ischemia. Ginsenoside Rb1 preconditioning reduced myocardial infarct size when compared with I/R group. Ginsenoside Rb1 induced myocardial protection was accompanied with increased eNOS expression and NO concentration and reduced plasma CK and LDH (P < 0.05). Moreover, the myocardial oxidative stress and tissue histological damage was attenuated by Ginsenoside Rb1 (P < 0.05). L-NAME abolished the protective effects of Ginsenoside Rb1. It is concluded that Ginsenoside Rb1 protects against myocardium ischemia/reperfusion injury in diabetic rat by enhancing the expression of eNOS and increasing the content of NO as well as inhibiting oxidative stress.

Effects of Shenfu injectio on expression of PTEN and PI3K during myocardial ischemia-reperfusion in diabetic rats

Objective To investigate the effect of Shenfu injectio （SFI） on the expression of phosphatase and tensin homolog deleted on chromosome 10 （PTEN） and phosphatidylinositol 3-kinase （PI3K） during myocardial ischemia-reperfusion （IR） in diabetic rats. Methods Thirty adult male diabetic SD rats weighing 220- 280 g were used in this study. Diabetes mellitus was induced with intraperitoneal streptozotocin 60 mg/kg and confirmed by fasting blood glucose 〉 16.7 mmol/L. The animals were randomly divided into 3 groups （ n = 10 eacb）：group Ⅰ sham operation （group S）; group Ⅱ IR and group Ⅲ SFI. Myocardial IR was produced by occlusion of left anterior descending branch （LAD） of coronary artery for 30 min followed by 120 min reperfusion in group IR and SFI. LAD was exposed but not occluded in group S. SFI was infused iv at 10ml·kg^-1·h^-1 before opening the thoracic cavity and at 3ml·kg^-1·h^-1 after opening the thoracic cavity in group SFI until the end of operation. Equal volume of Lactated Ringer＇s solution and hydroxyethyl starch was infused instead of SFI in group S and IR. The rats were killed and hearts removed at 120 min of reperfusion for microscopic examination and determination of cardiomyocyte apoptosis （by TUNEL）and expression of FIEN and PI3K （by immunohistochemical method）. PTEN/PI3K ratio, myocardial infarct size of left ventricle and apoptosis index were calculated. Correlation between apoptosis index and PTEN/PI3K ratio was analyzed. Results Myocardial infarct size and apoptosis index were significantly increased, while expression of PTEN and PI3K was up-regulated in group IR and SFI as compared with group S （P 〈 0.05 or 0.01）. PTEN/PI3K ratio was significantly decreased in group SFI as compared with group S （ P 〈 0.05 ） . Myocardial infarct size and apoptosis index were significantly decreased, PTEN expression was down-regulated, PI3K expression was up-regulated and PTEN/PI3K ratio was significantly decreased in group SFI as compared with group IR（ P 〈 0.05）. Myocardial pathological damage was attenuated in group SFI as compared with group IR. Apoptosis index was positively correlated to PTEN/PI3K ratio （ r = 0.452, P 〈 0.05）. Conclusion SFI can attenuate myocardial IR injury via down-regulating the expression of PTEN, up- regulating the expression of PI3K and activating PI3K/Akt signal pathway in diabetic rats. Key words: SHENFU DECOCTION; Diabetes mellitus; Myocardial reperfusion injury; 1-phosp- hatidylinositol 3-kinase; PTEN phosphohydrolase