[The myocardium protective effects of erythropoietin (EPO) in a rat model of asphyxia-induced cardiac arrest/cardiopulmonary resuscitation (CPR)].

OBJECTIVE: To examine the effects of EPO administration on the integrity of myocardium in a rat model of asphyxia-induced cardiac arrest/CPR. METHODS: 24 male Sprague-Dawley (SD) rats were randomly divided into three groups (8 each) to receive (1) cardiac arrest (induced by tracheal catheter clamping for 8 minutes)/CPR (by chest compressions and mechanical ventilation 8 minutes after cardiac arrest), (2) cardiac arrest/CPR +EPO (5 kU/kg, i.v, 3 minutes after restoration of spontaneous circulation (ROSC), and (3) no-treatment (control). The left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVEDP), and maximal positive/negative filling pressure change versus time (±dp/dt max) in the animals were recorded 30, 60, 90, and 120 minutes after ROSC. Blood and heart tissue samples were collected 120 minutes after ROSC for the examination of serum troponin I (cTnI) level, myocardium pathological change (by light/electronic microscopy), and myocardium apoptosis [by terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL) staining]. RESULTS: The LVSP, +dp/dt max and - dp/dt max absolute value in CPR group and EPO group were significantly lower than those of baseline at 30, 60, 90, 120 minutes after ROCS. In comparison with the control group, the LVSP( mm Hg, 1 mm Hg = 0.133 kPa: 119.52±12.68, 134.32±15.78 vs. 165.82±7.05), +dp/dt max (mm Hg/sec: 4457.14±826.22, 6019.85±1192.19 vs. 10325.93±773.09), and - dp/dt max ( mm Hg/sec: - 3956.04±952.37, - 4957.22±838.60 vs. - 8421.33±886.65) were significant lower (all P < 0.01) in the CPR and EPO group 30 minutes after ROSC, and such tendency remained till 120 minutes after ROSC: (LVSP: 124.62±8.07, 145.61±16.70 vs. 162.34±7.63; +dp/dt max: 4977.67±350.40, 7471.62±998.32 vs. 9999.39±727.96; - dp/dt max: - 4145.51±729.77, - 5895.64±787.30 vs. - 8089.75±981.52). Compared to the CPR group, the value of LVSP, + dp/dt max and - dp/dt max at all time points were significantly higher in EPO group (all P < 0.05). The LVEDP value was significantly higher ( P < 0.01) in both CPR and EPO group in comparison with the control (mm Hg/sec: 22.94±3.94, 11.18±2.58 vs. 2.89±0.70) 120 minutes after ROSC, and it was significantly lower in EPO group in comparison with CPR group ( P < 0.05). Light/electronic microscopy revealed myocardial necrosis, inflammatory cell infiltration, myocardial cell membrane integrity loss, mitochondrial swelling, and increased number of apoptotic cardiomyocyte (314.1±30.7 vs. 165.2±45.9 as in control) in CPR group samples. In contrast, the cardiomyocyte morphologic damages were significantly fewer in EPO group, so is the numbers of apoptotic cardiomyocyte (242.1±20.0 vs. 314.1±30.7, P < 0.05). In comparison with the control, the serum cTnI 120 minutes after ROSC was significantly higher (all P < 0.01) in CPR and EPO group (µg/L: 20.70±5.96,16.98±3.81 vs. 2.60±0.86), but no such difference was found between these two groups. CONCLUSION: EPO can attenuate the post resuscitation myocardial injury probably through its mitochondrial protective, anti-apoptotic effect.

[The anti-apoptosis effect of erythropoietin on neonatal rat cardiocytes during hypoxia/reoxygenation injury and its possible mechanism].

OBJECTIVE: To investigate the anti-apoptosis effect of erythropoietin (EPO) on myocardial cells after hypoxia/reoxygenation in vitro, and the relationship among protein kinase C (PKC), the mitochondrial ATP-sensitive potassium (mitoKATP) channel and EPO in the anti-apoptotic signaling pathways. METHODS: Cardiocytes were harvested from neonatal rats and cultured. Cultured myocardial cells were divided into the control group, the hypoxia/reoxygenation group, the EPO group and the chelerythrine group, and a hypoxia/reoxygenation model of cardiocytes was reproduced. Apoptosis rate was assayed by flow cytometry. Flavoprotein fluorescence was scanned by confocal laser microscope to assess the mitoKATP channel activity. RESULTS: Apoptosis rate was significantly higher in hypoxia/reoxygenation group than that of control group [(42.56+/-8.00)% vs. (17.88+/-2.00)%, P<0.05]. There was no statistically significant difference in flavoprotein fluorescence between this group and the control group [(0.278+/-0.170)x10(-2) vs. (0.149+/-0.050)x10(-2), P>0.05]. Myocardial cell apoptosis rate in EPO group was lower than that in hypoxia/reoxygenation group [(22.73+/-5.00)% vs. (42.56+/-8.00)%, P<0.05], and flavoprotein fluorescence intensity was significantly enhanced when compared with hypoxia/reoxygenation group [(2.201+/-1.090)x10(-2) vs. (0.278+/-0.170)x10(-2), P<0.01]. However, when chelerythrine was added, the anti-apoptosis effect of EPO was blocked, and the intensity of cardiocytes flavoprotein fluorescence was decreased [the apoptosis rate was (46.72+/-17.00)% and the flavoprotein fluorescence intensity was (0.986+/-0.320)x10(-2) ]. When compared with EPO group there was statistically significant difference (P<0.01 and P<0.05). CONCLUSION: Myocardial cell apoptosis occurs in hypoxia/reoxygenation injury, and EPO can protect rat cardiomyocytes from hypoxia/reoxygenation induced apoptosis. The protective effect is partly associated with the PKC/mitoKATP pathway.

[Role of macrophage migration inhibitory factor in mice with sepsis and after effect of its intervention].

OBJECTIVE: To investigate the expression profile of macrophage migration inhibitory factor (MIF) in serum and lung tissues of mice with sepsis, and to explore the effect of MIF antagonist ISO-1 on sepsis in a murine sepsis model. METHODS: Sepsis was reproduced in 40 mice by cecal ligation and puncture (CLP). Heart blood was obtained from 8 mice each at 12, 24, 36, 48 hours after CLP. The content of MIF in serum was determined by enzyme linked immunosorbent assay (ELISA). MIF mRNA and protein expressions in lung tissues of septic mice were assessed by reverse transcription-polymerase chain reaction (RT-PCR) or Western blotting. Another group of 40 mice were selected to investigate the role and the impact of MIF antagonist ISO-1 in septic mice. RESULTS: The content of MIF in serum was higher in septic mice than that in sham operation group, and it peaked at 36 hours, and decreased at 48 hours, but still higher than that in sham operation group (all P<0.01). The MIF mRNA and protein expression in lung tissues of septic mice were higher than those in sham operation group, beginning at 12 hours, and peaked at 48 hours (P<0.05 or P<0.01). ISO-1, which was the antagonist of MIF, could elevate the surviving rate of animals with sepsis [60% (12/20) vs. 25% (5/20), P<0.05]. CONCLUSION: MIF plays a role as a late mediator in sepsis, with a high expression of MIF in serum and lung tissue. ISO-1 can elevate the surviving rate in murine model of sepsis. It is concluded that MIF could be taken as a potential target of treatment of sepsis.