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Objective:To investigate the role of Caveolin (Cav-3)/extracellular signal-regulated kinase (ERK) signaling pathway in reduction of myocardial ischemia-reperfusion (I/R) injury by morphine preconditioning in rats with chronic heart failure.Methods:Clean-grade healthy adult male Sprague-Dawley rats, weighing 200-250 g, were used in this study.Chronic heart failure was induced by ligating the left anterior descending coronary artery for 6 weeks.Thirty-six Langendorff-perfused hearts with chronic heart failure were divided into 4 groups ( n=9 each) by a random number table method: myocardial I/R group (group IR), morphine preconditioning group (group MP), morphine preconditioning plus methyl-β-cyclodextrin group (group MP+ MβCD), and methyl-β-cyclodextrin group (group MβCD). Global myocardial I/R was induced by 30 min ischemia followed by 120 min reperfusion.In group MP, after 15 min of equilibration, hearts were subjected to 3 cycles of 5 min perfusion with K-H solution containing 1 μmol/L morphine for preconditioning followed by 5 min perfusion with K-H solution, 30 min in total, and after the end of treatment, hearts were subjected to 30 min ischemia followed by 120 min reperfusion.In group MP+ MβCD, hearts were perfused with K-H solution containing 200 μmol/L methyl-β-cyclodextrin at 10 min before preconditioning with morphine, and the other treatments were similar to those previously described in group MP.In group MβCD, hearts were perfused with K-H solution containing 200 μmol/L methyl-β-cyclodextrin at 40 min before ischemia, and the other treatments were similar to those previously described in group IR.At the end of 15 min of equilibration (T 0) and 5 and 10 min of reperfusion (T 1, 2), coronary outflow was collected for determination of actate dehydrogenase (LDH) activity by chemical colorimetry.Myocardial infarct size (IS) and area at risk (AAR) were measured, and IS/AAR was calculated at the end of 120 min reperfusion.Myocardial tissues of left ventricle were taken to detect the expression of Cav-3, ERK1/2 and phosphorylated ERK1/2 (p-ERK1/2) by Western blot, and p-ERK1/2/ERK1/2 ratio was calculated. Results:Compared with group IR, IS, IS/AAR and LDH activity in coronary outflow were significantly decreased, the expression of Cav-3 was up-regulated, and p-ERK1/2/ERK1/2 ratio was increased in group MP ( P<0.05). Compared with group MP, IS, IS/AAR and LDH activity in coronary outflow were significantly increased, the expression of Cav-3 was down-regulated, and p-ERK1/2/ERK1/2 ratio was decreased in group MP+ MβCD ( P<0.05). Conclusions:The mechanism by which morphine preconditioning reduces I/R injury may be related to activation of Cav-3/ERK signaling pathway in rats with chronic heart failure.
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Objective@#To evaluate the role of morphine preconditioning on necroptosis during myocardial ischemia-reperfusion (I/R) injury in the rats with heart failure.@*Methods@#Clean-grade adult male Sprague-Dawley rats, weighing 200-230 g, were injected with 2 mg/kg doxorubicin via the tail vein once a week for 6 consecutive weeks to establish the chronic heart failure model.Thirty rats with chronic heart failure at the end of 8th week were divided into 3 groups (n=10 each) using a random number table method: sham operation group (group S), I/R group and morphine preconditioning group (group MPC). Myocardial I/R was induced by occlusion of anterior descending branch of left coronary artery for 30 min followed by 120 min reperfusion in each group except group S. In group MPC, the rats were subjected to 3 cycles of 5-min infusion of 0.1 mg/kg morphine via the femoral vein at 5 min intervals before ischemia.The animals were sacrificed at the end of reperfusion, and the myocardial specimens were obtained for determination of the area at risk (AAR), infarct size (IS), expression of Fas mRNA (by quantitative real-time polymerase chain reaction) and expression of Fas, receptor-interacting protein 1 (RIP1) and RIP3 (by Western blot). The IS/AAR ratio was calculated.@*Results@#Compared with group S, the IS and IS/AAR ratio were significantly increased at the end of reperfusion, and the expression of Fas protein and mRNA, RIP1 and RIP3 was up-regulated in group I/R (P<0.05). Compared with group I/R, the IS and IS/AAR ratio were significantly decreased at the end of reperfusion, and the expression of Fas protein and mRNA, RIP1 and RIP3 was down-regulated in group MPC (P<0.05).@*Conclusion@#The mechanism by which morphine preconditioning reduces myocardial I/R injury is related to inhibiting necroptosis in the rats with heart failure.
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Objective To evaluate the role of morphine preconditioning on necroptosis during myocardial ischemia-reperfusion (I/R) injury in the rats with heart failure.Methods Clean-grade adult male Sprague-Dawley rats,weighing 200-230 g,were injected with 2 mg/kg doxorubicin via the tail vein once a week for 6 consecutive weeks to establish the chronic heart failure model.Thirty rats with chronic heart failure at the end of 8th week were divided into 3 groups (n=10 each) using a random number table method:sham operation group (group S),I/R group and morphine preconditioning group (group MPC).Myocardial I/R was induced by occlusion of anterior descending branch of left coronary artery for 30 min followed by 120 min reperfusion in each group except group S.In group MPC,the rats were subjected to 3 cycles of 5min infusion of 0.1 mg/kg morphine via the femoral vein at 5 min intervals before ischemia.The animals were sacrificed at the end of reperfusion,and the myocardial specimens were obtained for determination of the area at risk (AAR),infarct size (IS),expression of Fas mRNA (by quantitative real-time polymerase chain reaction) and expression of Fas,receptor-interacting protein 1 (RIP1) and RIP3 (by Western blot).The IS/AAR ratio was calculated.Results Compared with group S,the IS and IS/AAR ratio were significantly increased at the end of reperfusion,and the expression of Fas protein and mRNA,RIP1 and RIP3 was up-regulated in group I/R (P＜0.05).Compared with group I/R,the IS and IS/AAR ratio were significantly decreased at the end of reperfusion,and the expression of Fas protein and mRNA,RIP1 and RIP3 was down-regulated in group MPC (P＜0.05).Conclusion The mechanism by which morphine preconditioning reduces myocardial I/R injury is related to inhibiting necroptosis in the rats with heart failure.
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Objective To evaluate the role of μ opioid receptor in morphine preconditioning-induced reduction of myocardial ischemia-reperfusion (I/R) injury in rats with chronic heart failure.Methods Adult male Sprague-Dawley rats,weighing 170-230 g,in which chronic heart failure was induced by injecting doxorubicin via the tail vein,were studied.The rats were sacrificed and their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95％ O2-5％ CO2 at 37 ℃.Forty isolated rat hearts with I/R injury were randomly divided into 4 groups (n=10 each):group I/R,morphine preconditioning group (group MP),μ opioid receptor antagonist CTOP plus morphine preconditioning group (group CTOP+MP) and CTOP group.Myocardial I/R was induced by occlusion of the left coronary artery for 30 min followed by 120 min of reperfusion.In group MP,the hearts were perfused with K-H solution for 15 min,with K-H solution containing 1 μmol/L morphine for 5 min and with K-H solution for 5 min,3 cycles in total,and then the model of myocardial I/R was established.The hearts were perfused with K-H solution containing 1 μmol/L CTOP starting from 10 min before morphine preconditioning until 5 min of ischemia in group CTOP + MP.The hearts were perfused with K-H solution containing 1 μmol/L CTOP starting from 40 min before ischemia until 5 min of ischemia in group CTOP.The coronary effluent was collected at 15 min of equilibration (baseline) and 5 and 10 min of reperfusion to detect the activity of lactate dehydrogenase (LDH).Myocardial infarct size (IS) and the area at risk (AAR) were measured by 2,3,5-triphenyl-tetrazolium staining,and IS/AAR percentage was calculated.The expression of Bcl-2 and Bax mRNA was determined using uantitative real-time polymerase chain reaction,and the ratio of Bcl-2/Bax was calculated.Results Compared with group I/R,the IS and IS/AAR percentage were significantly decreased,the activity of LDH in coronary effluent was decreased,the expression of Bax mRNA was downregulated,the expression of Bcl-2 mRNA was up-regulated,and the Bcl-2/Bax ratio was increased in group MP (P＜0.05),and no significant change was found in the IS or IS/AAR percentage in CTOP and CTOP+ MP groups (P＞0.05).Compared with group MP,the IS and IS/AAR percentage were significantly increased,the activity of LDH in coronary effluent was increased,the expression of Bax mRNA was up-regulated,the expression of Bcl-2 mRNA was down-regulated,and the Bcl-2/Bax ratio was decreased in group CTOP+MP (P＜0.05).Conclusion The mechanism by which morphine preconditioning reduces myocardial I/R injury may be related to activating μ opioid receptors and thus maintaining the balance between Bcl2 and Bax gene expression in the rats with chronic heart failure.
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Objective To investigate the role of p38 mitogen-activated protein kinase (p38MAPK) signaling pathway in reduction of myocardial ischemia-reperfusion (I/R) injury by morphine preconditioning in the rats with chronic heart failure in vitro.Methods Adult male Sprague-Dawley rats,weighing 200-230 g,aged 6-7 weeks,in which doxorubicin 2 mg/kg was injected via the tail vein once a week for 6 consecutive weeks to induce chronic heart failure,were studied.At the end of 8th week,30 rats with chronic heart failure were randomly divided into 5 groups (n =6 each) using a random number table:sham operation group (group Sham),I/R group,morphine preconditioning group (group MPC),SB203580 (p38MAPK inhibitor) + morphine preconditioning group (group SBM),and SB203580 group (group SB).The hearts were quickly excised and passively perfused in a Langendorff apparatus and subjected to 30 min of occlusion of the anterior descending branch of the left coronary artery followed by 120 min of reperfusion to establish the model of myocardial I/R injury.After equilibration,the hearts were subjected to 3 cycles of 5 min perfusion with K-H solution containing morphine 1 μmol/L at 5-min intervals before ischemia in group MPC.In group SBM,the hearts were perfused with K-H solution containing SB203580 (5 μmol/L) for 45 min starting from l0 min before morphine preconditioning until 5 min of ischemia.In group SB,morphine preconditioning was not performed,and the hearts were only perfused with K-H solution containing SB203580 (5 μmol/L) starting from 40 min before ischemia until 5 min of ischemia.At 15 min of equilibration (baseline),5 and 10 min of reperfusion,the coronary effluent was collected to detect the activity of lactate dehydrogenase (LDH) using the chemical colorimetry.At 10 min of reperfusion,the expression of phosphor-p38MAPK (p-p38MAPK) in the myocardium was determined by Western blot in Sham,I/R and MPC groups.At 120 min of reperfusion,the area at risk (AAR),total areas of right and left ventricles (LV+RV),and infarct size (IS) were measured,and the IS/AAR ratio was calculated.Results Compared with group Sham,the LDH activity in coronary effluent during reperfusion and IS/AAR ratio were significantly increased in the other groups,and the expression of p-p38MAPK was significantly up-regulated in I/R and MPC groups (P＜0.05).Compared with group I/R,the LDH activity in coronary effluent during reperfusion was significantly decreased,the expression of p-p38MAPK was significantly up-regulated,and the IS and IS/AAR ratio were significantly decreased in group MPC (P＜0.05),and no significant change was found in the LDH activity in coronary effluent,IS and IS/AAR ratio in SBM and SB groups (P＞0.05).Compared with group MPC,the LDH activity in coronary effluent during reperfusion was significantly increased,and the IS and IS/AAR ratio were significantly increased in group SBM (P＜0.05).Conclusion The mechanism by which morphine preconditioning reduces myocardial I/R injury is related to activation of p38MAPK signaling pathway in the rats with chronic heart failure in vitro.
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Objective To investigate microRNAs ( miRNAs) expression profiling of cardiomyocytes in rats with heart failure, and predict miRNAs-regulated target genes and their functions.Methods Total of 18 male SD rats weighing 200-220 g were randomly divided into 2 groups:the control group ( CON) and the heart failure group (HF).The rats in HF group were injected by adriamycin via tail vein to induce heart failure, meanwhile in CON group, rats were received an equal volume of 0.9% sodium chloride intravenously.The cardiomyocytes isolated from the rat hearts in two groups and cultured overnight.After that, total RNA was extracted and then subjected to miRNA microarray to screen differentially expressed miRNAs.The reults of microarray were further verified by quantitative real-time PCR ( qRT-PCR ) .The target genes regulated by differentially expressed miRNAs were predicted by the software of Targetscan and miRanda.Bioinformatics analysis was performed to predict the miRNAs-regulated target genes and analyze the enriched gene ontology ( GO) and signaling pathway ( KEGG Pathway) .Results The results of miRNA microarray showed that a total of 37 miRNAs were differentially expressed in HF group as compared to CON group, among which 22 miRNAs were up-regulated and 15 miRNAs were down-regulated (P<0.01, FDR<0.05).The expression of miR-133b-5p (t=14.56, P<0.01), miR-6216 (t=9.32, P<0.01) and let-7e-5p (t=13.92, P<0.01) which were detected by qRT-PCR exhibited the similar tendency of up or down regulation to those shown in microarray results.Bioinformatics analysis indicated that miRNAs-regulated target genes were significantly enriched in 31 GOs (P<0.01, FDR<0.05) and 12 signal pathways (P<0.05, FDR<0.05), among which ubiquitin-proteasome system, MAPK signaling pathway and Toll like siganling pathway exhibited a higher enrichment. Conclusion MiRNA expression profile on cardiomyocytes in rat with adriamycin-induced heart failure was significantly changed.These differentially expressed miRNAs might participate in the process of heart failing by regulating their target genes in rat cardiomyocytes.
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Objective To evaluate the role of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways in reduction of ischemia-reperfusion (I/R) injury by morphine preconditioning in the rats with heart failure.Methods Adult male Sprague-Dawley rats,weighing 200-230 g,in which doxorubicin 2 mg/kg was injected via the tail vein once a week for 6 consecutive weeks to induce chronic heart failure,were studied.At the end of 8th week,45 rats with chronic heart failure were randomly divided into 5 groups (n =9 each) using a random number table:sham operation group (group S),group I/R,morphine preconditioning group (group MPC),SP600125 (JNK inhibitor) + morphine preconditioning group (group MSP) and SB203580 (p38MAPK inhibitor) + morphine preconditioning group (group MSB).Myocardial I/R was induced by 30 min occlusion of the anterior descending branch of the coronary artery followed by 120 min reperfusion in each group except group S.In group MPC,the rats were subjected to 3 cycles of 5-min infusion of 0.1 mg/kg morphine via the femoral vein at 5 min interval before ischemia.In MSP and MSB groups,SP600125 0.5 mg/kg and SB203580 0.2 mg/kg were injected via the femoral vein,respectively,at 10 min before morphine preconditioning.The animals were sacrificed at 120 min of reperfusion,and the myocardial specimens were obtained for determination of the total areas of right and left ventricles (LV+RV),area at risk (AAR),infarct size (IS),and expression of PKC δ in myocardial tissues (by immunohistochemistry),and IS/AAR ratio was calculated.Results There was no significant difference in LV+RV and AAR between the five groups (P＞0.05).Compared with group S,IS and IS/AAR were significantly increased,and the expression of PKC δ was upregulated in I/R and MSB groups (P＜0.05).Compared with group I/R,IS and IS/AAR were significantly decreased,and the expression of PKC δ was down-regulated in MPC and MSP groups (P＜0.05).Compared with group MPC,IS and IS/AAR were significantly increased,and the expression of PKC δ was upregulated in group MSB (P＜0.05),and no significant change was found in the parameters mentioned above in group MSP (P＞0.05).Conclusion Activation of p38MAPK signaling pathway is involved in reduction of myocardial I/R injury by morphine preconditioning,and the mechanism is related to down-regulation of PKC δ expression in rats with heart failure;JNK signaling pathway is not involved in this process.
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Aim To investigate the roles of mitogen-ac-tivated protein kinases ( MAPK ) pathways in the pro-tective effects of remifentanil preconditioning against is-chemia/reperfusion injury of isolated heart in rats with heart failure. Methods Adult male SD rats were injected with adriamycin via tail vein for 6 weeks to induce heart failure. The rats were confirmed chronic heart failure through echocardiography and randomly divided into 9 groups(n=6)as follows: sham group, ischemia/reperfusion group ( IR) , remifentanil precon-ditioning group( RPC) , ERK inhibitor PD98059+RPC group ( RPD ) , p38 inhibitor SB203580 +RPC group ( RSB ) , JNK inhibitor SP600125 + RPC group ( RSP ) , and the inhibitor control groups ( PD , SB and SP) . All hearts were linked to the Langendorff ap-paratus. The coronary effluent was collected to detect the activity of lactate dehydrogenase ( LDH ) at base-line, 5 min and 10 min after reperfusion, respectively. Infarct size ( IS) and area at risk ( AAR) were deter-mined by 2, 3, 5-triphenyl-tetrazolium (TTC) staining at the end of reperfusion. Left ventricular developed pressure ( LVDP), ± dp/dtmax and heart rate ( HR) were recorded to evaluate cardiac function in each group. Results When compared with IR group, RPC significantly reduced IS / AAR and decreased the ac-tivity of LDH at 5 min and 10 min after reperfusion. However, SP600125 almost thoroughly abolished the protective effects of RPC, as evidenced by the in-creased value of IS / AAR and the high activity of LDH. In addition, PD98059 also partly blocked the effects of RPC, while SB203580 showed no influence on RPC. Meanwhile, the hemodynamic parameters such as LVDP, HR and ± dp/dtmax were not signifi-cantly different in any group except sham group. Con-clusion JNK and ERK pathways may play an impor-tant role in cardioprotective effects of remifentanil pre-conditioning against ischemia/reperfusion injury in rats with heart failure.
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Objective To evaluate the role of nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signal transduction pathway in mitigation of myocardial ischemia-reperfusion injury by intrathecal morphine postconditioning in rats.Methods Forty-eight male Sprague-Dawley rats in which intrathecal catheters were successfully placed without complications,weighing 250-350 g,were randomly assigned into 8 groups (n =6 each):normal saline group (NS group),morphine postconditioning group (Mp group),1-NG-nitroarginine methyl ester (L-NAME,NO synthase inhibitor) + morphine postconditioning group (L-NAME + MP group),ODQ (guanylate cyclase inhibitor) + morphine postconditioning group (ODQ + MP group),KT5823 (PKG inhibitor) + morphine postconditioning group (KT5823 + MP group),L-NAME group,ODQ group and KT5823 group.Myocardial ischemia was induced by 30 min of occlusion of anterior descending branch of left coronary artery followed by 2 h of reperfusion.At 25 rin of ischemia,normal saline 10 μl was intrathecally infused over 5 min in group NS,and morphine (3 μg/kg,10 μl) was intrathecally infused over 5 min in group MP.L-NAME (30 nmol,10 μl),ODQ (11 nmol,10 μl) and KT5823 (20 pmol,10 μl) were intrathecally injected at 10 rin before morphine postconditioning in L-NAME + MP,ODQ + MP and KT5823 + MP groups,respectively.Before myocardial ischemia (T0),at 25 and 30 min of ischemia (T1-2),and at 120 min of reperfusion (T3),MAP and HR were recorded,and rate-pressure product (RPP) was calculated.The rats were sacrificed at T3,and myocardial specimens were obtained for determination of myocardial infarct size as a percentage of area at risk (IS/AAR).Results MAP,HR and RPP were significantly lower at T1-3 than at T0 in each group.Compared with group NS,MAP was significantly increased at T3,and IS/AAR ratio was decreased in MP group,and no significant changes were found in the other groups.Compared with group MP,IS/AAR ratio was significantly increased in L-NAME + MP,ODQ + MP and KT5823 + MP groups,and no significant changes were found in the other groups.Conclusion NO-cGMP-PKG signal transduction pathway plays an important role in mitigation of myocardial ischemia-reperfusion injury by intrathecal morphine postconditioning in rats.
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Objective To evaluate the roles of 1-phosphatidylinositol 3-kinase (PI3K) and extracellular signal-regulated kinase (ERK) signaling pathways in reduction of ischemia-reperfusion (I/R) injury to the isolated hearts by morphine preconditioning in the rats with chronic heart failure.Methods Adult male Sprague-Dawley rats,weighing 200-230 g,in which doxorubicin 2.0 mg/kg was injected via the tail vein once a week for 6 weeks to induce chronic heart failure,were studied.At the end of 8th week,42 rats with chronic heart failure were randomly divided into 7 groups (n =6 each) using a random number table:sham operation group (group S),I/R group,morphine preconditioning group (group MP),PD98059 (ERK inhibitor) + morphine preconditioning group (group PD + MP),wortmannin (PI3K inhibitor) + morphine preconditioning group (group WT + MP),PD98059 group (group PD) and wortmannin group (group WT).The hearts were quickly excised and passively perfused in a Langendorff apparatus and subjected to 30 min of occlusion of the left coronary artery followed by 2 h of reperfusion to establish the model of I/R injury.In group S,the hearts were only sutured,but not ligated and were continuously perfused with K-H solution for 195 min.In group I/R,the hearts were perfused with K-H solution for 45 min before ischemia.In group MP,the hearts were perfused with K-H solution for 15 min,with K-H solution containing morphine 1 μmol/L for 5 min and then with K-H solution for 5 min (3 cycles in total) before ischemia.In PD + MP and WT + MP groups,the hearts were perfused with K-H solution containing PD98059 (10 μmol/L) and wortmannin (100 nmol/L),respectively,starting from 10 min before morphine preconditioning until 5 min of ischemia.In PD and WT groups,the hearts were perfused with K-H solution containing PD98059 (10 μmol/L) and wortmannin (100 nmol/L),respectively,starting from 40 min before ischemia until 5 rin of ischemia.At 15 min of equilibration (baseline) and 5 and 10 min of reperfusion,the coronary flow was collected to detect the activity of lactate dehydrogenase (LDH).Infarct size (IS) and area at risk (AAR) were measured at the end of reperfusion and IS/AAR ratio was calculated.Results Compared with group S,LDH activity was significantly increased at 5 and 10 min of reperfusion,IS and IS/AAR ratio were also increased (P ＜ 0.05),and no significant change was found in AAR in group I/R (P ＞ 0.05).Compared with group I/R,LDH activity was significantly decreased at 5 min of reperfusion,IS and IS/AAR ratio were also decreased (P ＜ 0.05),and no significant change was found in AAR in group MP,and no significant change was found in LDH activity,IS,AAR and IS/AAR ratio in WT and PD groups (P ＞ 0.05).Compared with group MP,LDH activity was significantly increased at 5 and 10 min of reperfusion (P ＜ 0.05),and IS and IS/AAR ratio were decreased in group PD + MP,and no significant change was found in LDH activity,IS,AAR and IS/AAR ratio in group WT + MP (P ＞ 0.05).Conclusion Activation of ERK signaling pathway is involved in reduction of I/R injury to isolated hearts by morphine preconditioning in rats with chronic heart failure,however,PI3K signaling pathway has no such effect.
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Objective To evaluate the effects of morphine preconditioning on the expression of microRNAs (miRNAs) during hypoxia-reoxygenation (H/R) in isolated cardiomyocytes in rats with heart failure.Methods Healthy adult male Sprague Dawley rats,w eighing 200-220 g,were used in this study.Adriamycin 2.0 mg/kg was injected once a week for 6 weeks via the tail vein to induce heart failure.The cardiomyocytes were isolated from the failing hearts of rats and seeded in 24-well plates or in 60 mm diameter dishes.The cells were then randomly divided into 3 groups (n =16 each) using a random number table:control group (group C); group H/R;morphine preconditioning group (group MP).The cells were cultured in normal culture atmosphere in group C.After being exposed to hypoxic air (5％ CO2-95％ N2) for 90 min,the cells were returned to the high-glucose DMEM supplemented with 10％ newborn bovine serum and were then cultured for 120 min in H/R and MP groups.In group M,the cells were cultured in morphine culture medium (final concentration of morphine 0.3 μmol/L) for 10 min and then were returned to the culture medium without morphine and cultured for 30 min immediately before hypoxia.At 120 min of reoxygenation,the cells of 8 wells in each group were chosen to detect the cell viability and lactate dehydrogenase (LDH) activity (by Typan blue staining).All the RNAs were extracted from the cardiomyocytes of the left 8 wells in each group and subjected to miRNA microarray to screen differentially expressed miRNAs.Results The cell viability was significantly lower,the activity of LDH was higher,the expression of miR-6216 and let7e-5p was higher,and the expression of miR-133b-5p was lower in H/R and MP groups than in group C (P ＜ 0.05).Compared with H/R group,the cell viability was significantly increased,the activity of LDH was decreased,the expression of miR-133b-5p was up-regulated,and the expression of miR-6216 and let-7e-5p was down-regulated in MP group (P ＜ 0.05).Conclusion Morphine preconditioning reduces H/R injury to isolated cardiomyocytes in rats with heart failure through regulating the expression of miRNAs such as miR133b-5p,miR-6216 and let-7e-5p.
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Objective To evaluate the role of opioid receptors and phosphatidylinositol 3-kinase/proteinserine-threonine kinases (PI3K/Akt) and extracellular signal-regulated kinase (ERK) signaling pathways in reduction of hypoxia/reoxygenation (H/R)-induced injury to cardiomyocytes by remifentanil preconditioning in rats.Methods Primary cardiomyocytes were obtained from adult male Sprague-Dawley rats and cultured in DMEM culture medium.The cells were seeded in 48-well plates (density 2 × 104 cells/ml,500 μl/well) and randomly divided into 12 groups (n =9 each):control group (group C),group H/R,hypoxia preconditioning group (group HPC),remifentanil preconditioning (RPC) group,naltrindole (δ receptor antagonist) + RPC group,nor-binaltorphimine (κ receptor antagonist) + RPC group (BNI + RPC group),wortmannin (PI3K inhibitor) + RPC group (W+ RPC group),PD98059 (ERK inhibitor) + RPC group (PD + RPC group),NTD group,BNI group,W group and PD group.In group H/R,the cardiomyocytes were exposed to 90 min of hypoxia,followed by 120 min of reoxygenation.In group HPC,the cardiomyocytes were exposed to 10 min of hypoxia,followed by 30 min of reoxygenation before H/R.In group RPC,the cardiomyocytes were preconditioned with remifentanil with the final concentration of 1 μmol/L for 10 min,followed by 30 min routine culture before H/R.In NTD + RPC,BNI + RPC,W + RPC and PD + RPC groups,naltrindole 5μmol/L (final concentration),nor-binaltorphimine 5 μmol/L (final concentration),wortmannin 0.1 μmol/L (final concentration) and PD98059 30μmol/L (final concentration)were added,respectively,and then the cells were coincubated with remifentanil for 10 min,followed by 30 min routine culture before H/R.The viability of cardiomyocytes,cell apoptosis and activity of lactate dehydrogenase (LDH) in the culture medium were detected.The apoptosis rate (AR) was calculated.Results Compared with group C,the viability of cardiomyocytes,AR and activity of LDH in the culture medium were significantly increased in group H/R (P ＜ 0.05).Compared with group H/R,the viability of cardiomyocytes,AR and activity of LDH in the culture medium were significantly decreased in HPC,RPC and BNI + RPC groups (P ＜ 0.05),and no significant changes were found in the parameters mentioned above in NTD + RPC,W + RPC,PD + RPC,NTD,BNI,W,and PD groups (P ＞ 0.05).The viability of cardiomyocytes was significantly lower,and the AR and activity of LDH in the culture medium were higher in NTD + RPC,BNI + RPC,W + RPC,and PD + RPC groups than in RPC group (P ＜ 0.05).Conclusion Remifentanil preconditioning activates PI3K/Akt and ERK signaling pathways possibly through activating δ opioid receptors thus attenuating H/R-induced injury to cardiomyocytes in rats.