Cardiac protection from myocardial ischemic postconditioning and remote postconditioning during myocardial ischemia/reperfusion injury in rabbits / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To observe whether there are some differences between myocardial postconditioning and remote postconditioning, and whether there is additional cardiac protection when they are used combined during myocardial ischemia/reperfusion injury in rabbits.</p><p><b>METHODS</b>Thirty healthy New Zealand rabbits which were randomly divided into 5 groups (n = 5): ischemic control group (CON), sham operation group (Sham), myocardial postconditioning group (MPostC), remote postconditioning group (RPostC), myocardial postconditioning plus remote postconditioning group (MPostC + RPostC). Acute myocardial infarction was induced by 45 minutes occlusion on left circumflex coronary artery (LCX) and 2 hours reperfusion in all anesthetized open-chest rabbits except the Sham, the coronary occlusion and reperfusion were determined by changes of ECG and cardiac color. Skeletal muscle ischemia model was induced by extrinsic iliac arteries occlusion and reperfusion with artery clamps. The condition that the extrinsic iliac arteries were occluded or reperfused could be tested by according to the distal arterial pulse. Plasma creatine kinase (CPK) activity and lactate dehydrogenase (LDH) activity were measured at baseline, the end of ischemia, after 1 hour and 2 hours of reperfusion respectively. The extent of myocardial infarction was assessed by triphenyltetrazolium (TTC) staining and measured by area ratio of AN/AAR.</p><p><b>RESULTS</b>Compared with the Con, myocardial infarct size was significantly reduced in MPostC and RpostC group (P < 0.05). But there was no significant difference between MPostC and RPostC group. Combined MPostC and RPostC markedly enhanced myocardial protection (P < 0.05). The trend of CPK and LDH release was similar to the trend of myocardial infarct size.</p><p><b>CONCLUSION</b>Both MPostC and RPostC induced cardiac protection. There was no significant difference between MPostC and RPostC. Combined MPostC and RPostC induced markedly additive effect on myocardial protection.</p>

Cardioprotective effects of limb ischemic postconditioning by different strength and time in rabbits / 中国应用生理学杂志

<p><b>OBJECTIVE</b>In this study, we try to find the better protocol of limb ischemia postconditioning by observing different protective effects of limb ischemic postconditioning (different strength and time windows in rabbits).</p><p><b>METHODS</b>42 healthy New Zealand rabbits were randomly divided into 7 groups (n = 6): Sham; Control (CON); Skeletal muscle postconditioning (SP); 6 min-delayed skeletal muscle postconditioning (6M-DSP); 1 min-delayed skeletal muscle postconditioning (1M-DSP); Strengthen skeletal muscle postconditioning (SSP); Weakened skeletal muscle postconditioning (WSP). Acute ischemia/reperfusion (I/R) model was induced by 45 minutes occlusion on left circumflex coronary artery (LCX) and 2 hours reperfusion in all anesthetized open-chest rabbits except the Sham. Limb ischemia was induced by external iliac arteries occlusion and reperfusion through artery clamps. The extent of myocardial infarction was assessed by triphenyltetrazolium (TTC) staining. Blood serum creatine kinase (CK) activity and lactate dehydrogenase (LDH) activity were measured at baseline,the end of ischemia, after 1 hour and 2 hours of reperfusion respectively.</p><p><b>RESULTS</b>Compared with the CON, the weight ratio and area ratio of myocardial infarction size were significantly decreased by 49.97% and 43.78% in SP, by 42.32% and 42.68% in 1M-DSP, by 48.36% and 48.86% in SSP (P < 0.05). But there was no significant difference between SP and 1M-DSP and SSP (P > 0.05). Otherwise, compared with the CON, myocardial infarct size was not significantly reduced in 6M-DSP or WSP (P > 0.05). The change of CK was similar to the trend of myocardial infarct size.</p><p><b>CONCLUSION</b>The limb ischemia strength of 5 mini/1 minR x 1 cycle could significantly reduce the myocardial ischemia/ reperfusion injury in rabbits, if it was achieved before myocardial reperfusion.</p>

Effects of rabbit limbs ischemia/ reperfusion on myocardial necrosis and apoptosis / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To investigate the effects of rabbit limbs ischemia/reperfusion on myocardial necrosis and apoptosis in vivo.</p><p><b>METHODS</b>Thirty-six healthy new zealand rabbits were randomly divided into 3 groups: (1) Sham group; (2) I/R(Ischemia/reperfusion) group; (3) RPostC (remote postconditioning) group. The activity of blood serum creatine kinase (CK) and lactate dehydrogenase (LDH) were measured at baseline, the end of ischemia after 60 min and 120 min of reperfusion respectively. The extent of myocardial ischemia and the scope of myocardial infarction were assessed by evans blue and Triphenyl tetrazolium chloride (TTC). The myocardial cell's apoptosis at the area of myocardial ischemia was estimated by Tunel. Protein expression of caspase-3, Bcl-2 and Bax in myocardial ischemic area were analyzed with the method of immunohistochemistry.</p><p><b>RESULTS</b>Compared with I/R group, the myocardial infarct size and the CK activity were significantly reduced in RPostC group. The Tunel positive index of RPostC group in ischemic myocardium was significantly lower than that in I/R group (21.79% +/- 1.07% vs 35.81% +/- 1.10%, P < 0.05). Caspase-3 positive cells index was calculated with randomly selected five regions in each slide and then the positive cells in per hundred cells were calculated. The RPostC group of caspase-3 positive cells was significantly lower than that in I/ R group(25.03% +/- 1.16% as 39% +/- 2.43%, P < 0.05). Compared with the sham group, the Bax protein expression index and the Bcl-2 protein expression index of I/R group and RPostC group were increased. The Bax/Bcl-2 ratio of RPostC group decreased, while it was increased in I/R. Compared with the I/R group, the Bax protein expression and Bax/Bcl-2 ratio of RPostC group significantly reduced, but the expression index of Bcl-2 ratio was significantly increased, the differences were statistically significant.</p><p><b>CONCLUSION</b>Limbs ischemia/postconditioning could significantly reduce necrosis and apoptosis of ischemia/reperfusion myocardium. The mechanism of reducing the myocardial cell apoptosis may have relation to inhibiting the activation of pro-apoptotic gene caspase-3 and increased expression of Bcl-2.</p>

Impact of application time of aspirin and clopidogrel on platelet aggregation in patients with acute coronary syndrome / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the impact of various application time of aspirin and clopidogrel on the circadian rhythm changes of platelet aggregation in patients with acute coronary syndrome.</p><p><b>METHODS</b>Patients with acute coronary syndrome were divided into day-time (8:00) and night-time (20:00) medication group (n = 15 each). After plasma concentration reached steady state, platelet aggregation was assessed at 5 time points within 24 hours with a mobile four-channel whole blood impedance aggregometer. The platelet aggregation was induced by ADP and arachidonic acid. Thereafter, the two groups were exchanged and platelet aggregation was assessed in the same way post plasma steady state.</p><p><b>RESULTS</b>Arachidonic acid-induced platelet aggregation was the highest at 10:00 Am [(7.96 +/- 3.64) ohm] and the lowest at 0:00 [(6.12 +/- 3.29) ohm, P > 0.05] in day-time group. Platelet aggregation was the highest at 20:00 [(9.40 +/- 5.39) ohm] and the lowest at 10:00 [(5.46 +/- 3.93) ohm], P < 0.05). ADP-induced platelet aggregation was the highest at 10:00 and the lowest at 16:00 in day-time group (P > 0.05) and was the highest at 20:00 and the lowest at 10:00 in night-time group (P > 0.05). Platelet aggregation induced by two inducers was significantly higher at 10:00 in day-time group compared to values in night-time group (all P < 0.05).</p><p><b>CONCLUSION</b>Taking aspirin and clopidogrel at 20:00 was superior to taking the same medications at 8:00 for inhibiting peak platelet aggregation in the morning.</p>

Gene polymorphism of CYP450 2C9 and VKORC1 in Chinese population and their relationships to the maintaining dosage of warfarin / 中华流行病学杂志

Objective To investigate the distribution of gene polymorphism of CYP450 2C9 and VKORC1-1639A/G in the Chinese population as well as the difference of genetic polymorphism between Chinese Han population and other ethnic populations.Contribution of CYP2C9 and VKORC1 genotype to the maintenance doses on warfarin was also studied.Methods The genotype and allele frequencies were calculated and compared with those in other populations.One hundred and one patients with stable anticoagulation with warfarin under a target international normalized ratio(INR)of 2.0 to 3.0 were enrolled for studying the relationship between the CYP2C9 and VKORC1 gene polymorphism and the warfarin maintaining dosage.Results CYP450 2C9~*3 + 1075C/A allele frequencies were:AA in 449 cases(92.2%),AC in 36 cases(7.4%)and CC in 2 cases(0.4%),respectively.VKORC1-1639A/G allele frequencies were AA in 415 cases(85.2%),GA in 72 cases(14.8%),but GG in no case(0.0%),respectively.When linear stepwise regression analysis was used to identify factors contributing to warfarin stable dose,the final equation was:ln(D)=0.346 + 0.017(weight)-0.376(CYP450 2C9~*3 + 1075C/A)+ 0.148(VKORC1-1639A/G)-0.002(age)(r=0.827,P=0.02).Conclusion There existed significant gene polymorphism CYP450 2C9~*3 + 1075C/A and VKORC1-1639A/G in the Chinese Han population.Both Gene polymorphisms of CYP450 2C9*3 + 1075C/A and VKORC1-1639A/G were significantly affecting the maintaining dose of warfarin in the Chinese population.

Effects of remote preconditioning induced by skeletal muscle ischemia on myocardial cells apoptosis and roles of opioid receptors in pigs / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effect on myocardial apoptosis and Bcl-2/Bax induced by remote preconditioning (RP) and to discuss the hypothesis from opioid receptors in pigs.</p><p><b>METHODS</b>Skeletal muscle ischemia was performed in pigs by occlusion of the femoral artery (FAO) for 15 min followed by a 10 min of reperfusion. Infarction of the heart was induced by 40 min of left anterior descending coronary artery (LAD) occlusion followed by 120 min reperfusion. In the RP model induced by FAO, the role of opioid receptors was investigated by using antagonist of the opioid receptors (naloxone). The signal transduction pathway of RP was investigated by using hexamethonium. Apoptosis of left ventricular samples from nonischemic and ischemic areas was detected in situ with end-labeling (TUNEL) method and measured by flow cytometry. Bcl-2 and Bax was also measured by flow cytometry.</p><p><b>RESULTS</b>(1) The apoptosis rate in ischemic myocardium in RP group measured by flow cytometry was lower (4.43% +/- 0.74%) compared with that in CONT group (15.4% +/- 1.15%), but Bcl-2/Bax was higher (1.36 +/- 0.09, CONT group: 0.56 +/- 0.08). (2) The protective effect could be prevented by naloxone used before RP protocol (apoptosis rate: 13.0% +/- 0.56% and Bcl-2/Bax: 0.69 +/- 0.18, P < 0.05). (3) Naloxone had no effect on apoptosis rate in CONT group. (4) Hexamethonium used before RP protocol had no effect on apoptosis rate and bcl-2/bax. Apoptotic cardiomyocytes detected in TUNEL correspond to the above.</p><p><b>CONCLUSION</b>RP induced by skeletal muscle ischemia could prevent myocardium from apoptosis, in which Bcl-2 and Bax might take part in regulation and control. Furthermore opioid receptors could take part in triggering the course and a neuronal signal transmission from the remote area to heart could be excluded.</p>

Crosstalk between ERK1/2 and STAT3 in the modulation of cardiomyocyte hypertrophy induced by cardiotrophin-1 / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway and the extracellular signal-regulated kinases 1/2 (ERK1/2) pathway are the two major independent signal transduction pathways. However, it has recently been found that STAT3 may be negatively regulated by ERK1/2 in gp130-dependent signaling. Cardiotrophin-1 (CT-1), a potent novel hypertrophic cytokine, depends on gp130 to induce signaling and depends on STAT3 to exert hypertrophic effect. In this study, we examined whether STAT3 activity was negatively regulated by ERK1/2 during CT-1-induced signaling in rat cardiomyocytes and, if so, whether such crosstalk interfered with the hypertrophic effect of CT-1 and, furthermore, whether the mechanism underlying the crosstalk involved phosphorylation of serine 727 (S727) in STAT3.</p><p><b>METHODS</b>The activities of ERK1/2 and STAT3 were assessed by in-gel kinase assay and Western blot analysis, respectively. The role of S727 phosphorylation in the crosstalk between ERK1/2 and STAT3 was determined by a transient transfection study using a STAT3S727A mutant. Cardiomyocyte hypertrophy was evaluated by the cellular protein-to-DNA ratio and [(3)H]-leucine incorporation.</p><p><b>RESULTS</b>CT-1 simultaneously activated both ERK1/2 and STAT3 in rat cardiomyocytes. Inhibition of ERK1/2 by U0126 resulted in an increase of CT-1-induced tyrosine phosphorylation of STAT3 and, consequently, the protein-to-DNA ratio and [(3)H]-leucine incorporation. Transient transfection of the cells with STAT3S727A had no significant effect on CT-1-induced tyrosine phosphorylation of STAT3.</p><p><b>CONCLUSIONS</b>STAT3 is activated by CT-1 in rat cardiomyocytes, but full activation is mitigated by the simultaneous activation of ERK1/2. The inhibition of ERK1/2 increases the activity of STAT3, which, in turn, enhances the hypertrophic effect of CT-1. The crosstalk between ERK1/2 and STAT3 is independent of the phosphorylation of the S727 in STAT3. Such crosstalk may contribute to the development of adequate cardiac hypertrophy.</p>

Myocardial protection and mechanism of Puerarin Injection on patients of coronary heart disease with ischemia/reperfusion / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To explore the protective effect and the mechanism of Puerarin Injection (PI) on myocardial ischemia reperfusion in patients with coronary heart disease (CHD) and angina pectoris (AP).</p><p><b>METHODS</b>Seventy-eight patients with AP planned to receive the PTCA and stenting treatment were randomly divided and single-blindedly into the conventional group and the PI group. Based on the conventional treatment and pre-operational preparation, the PI group was given 200 ml of PI by intravenous dripping once a day, beginning from one week before operation, but to the conventional group, normal saline was given for instead. The condition of AP attack in balloon dilatatory stage of PTCA was observed and change of ST segment of ECG detected by a 12-lead ECG monitor. The blood levels of von Willebrand factor (vWF:Ag), nitric oxide (NO) and endothelin-1 (ET-1) were also observed before and after treatment.</p><p><b>RESULTS</b>As compared with those in the conventional group, number of patients having AP attack and ST segment change in PTCA process was lessened in the PI group, with blood levels of vWF:Ag and ET-1 obviously lower, and NO content obviously higher than those in the conventional group,</p><p><b>CONCLUSIONS</b>PI could protect the myocardium in 2-3 days after ischemia reperfusion, one of the possible reasons is that PI can simulate the late phase of ischemic preconditioning, which may be related to its effect in lowering plasma vWF:Ag and ET-1, and increasing the serum NO content.</p>