Objective: To investigate the function of the ATP-sensitive K+(KATP) channel activation on the protective effect of hypercarbonic acidosis preconditioning on rabbit myocardial cells. Methods: Thirty-two rabbits were randomly divided into 4 groups (n = 8 for each group): pseudo-operation group (group P), ischemia and reperfusion group(group IR), hypercarbonic acidosis group(group H) and hypercarbonic acidosis+ glybenzcyclamide group (group H+G). Animals were ventilated normally in group IR and group P, tidal volume 15 mL/kg, breathing rate 35 bpm .The PETCO_2 was maintained at the level of 40-50 mm Hg for 30 minutes. Animals received low-frequency, low volume ventilation in group H group H+G, tidal volume 10 ml/kg, breathing rate 25 bpm to achieve hypercarbonic acidosis. The target value of PETCO_2 was 75-85 mm Hg. This value was maintained for 5 minutes. The animals then were ventilated normally to make the PETCO_2 return to 40-50 mm Hg. Animals were injected with 0.3 mg/kg glybenzcyclamide 10min before achieving hypercarbonic acidosis with hypoventilation in group H+G. Animals received ligation of left anterior branch artery for 30 minutes and reperfusion for 180 minutes in each group except P group. The myocardial ischemia area, the myocardial infarction area and their ratios were calculated by the ismaeil methods. Results: The ratio of the myocardial infarction area to the myocardial ischemia was significantly less in group H than those of group IR and group H+G (P < 0.01). The value of the ratio was similar between group H+G and group IR(P > 0.05). Conclusion: Hypercarbonic acidosis preconditioning can protect the cardiomyocytes by activating the KATP channel.

Objective To investigate the effect of high concentration carbon dioxide preconditioning on lipid peroxidation during myocardial ischemia-reperfusion (I/R) in rabbits. Methods Twenty-four New Zealand white rabbits weighing 2.0-3.9 kg were randomly divided into 3 groups ( n = 8 each): sham operation group (group S) , I/R group, high concentration carbon dioxide preconditioning group (group H) . The amimals were tracheal intubated and mechanically ventilated. In groups S and I/R, fresh gas flow was set at 0.3 L/min (100% O2 ), respiratory rate 30-40 bpm and tidal volume IS ml/kg, and PETCO2 was maintained at 40-50 mm Hg for 30 min. In group H, fresh gas flow was set at 0.3 L/min (100% O2), respiratory rate 20-30 bpm and tidal volume 10 ml/kg, PETO2 was maintained at 75-85 mm Hg for 5 min, and then all the ventilatory parameters were adjusted to the same as those in groups S and I/R. Myocardial I/R was produced by occlusion of left anterior descending branch of coronary artery for 30 min followed by 3 h reperfusion after preconditioning in groups I/R and H. The animals were sacrificed at the end of reperfusion and myocardial tissues obtained for determination of the superoxide dismutase (SOD) activity and malondialdehyde (MDA) content and examination of the ultrastnicture of myocardium with the transmission electron microscope. Results The SOD activity was significantly lower, while MDA content higher in group I/R than in group S ( P ＜ 0.01) . The SOD activity was significantly higher, while MDA content lower in group H than in group I/R ( P ＜ 0.01) . The myocardial injury was attenuated in group H compared with group I/R. ConclusionHigh concentration carbon dioxide preconditioning can reduce myocardial I/R injury in rabbits through inhibiting lipid peroxidation.

This study observed the protective effect of hypercapnic acidosis preconditioning on rabbit heart suffered from ischemia-reperfusion injury. Hypercapnic acidosis was established in animals with mechanical hypoventilation before ischemia-reperfusion. Thirty-two rabbits were randomly divided into 4 groups, with each having 8 animals in term of the degree of acidification: hypercapnic acidosis group A (group A), hypercapnic acidosis group B (group B), hypercapnic acidosis group C (group C), ischemia and reperfusion group (group IR). Animals in group IR were ventilated normally (tidal volume: 15 mL/kg, breathing rate 35 bpm). The PETCO(2) was maintained at the level of 40-50 mmHg for 30 min. Animals in groups A, B, C received low-frequency, low-volume ventilation to achieve hypercarbonic acidosis and the target levels of PETCO(2) were 75-85,65-75, 55-65 mmHg, respectively, with levels being maintained for 5 min. The animals then were ventilated normally to lower PETCO(2) to 40-50 mmHg. The left anterior branch artery of all the animals was ligated for 30 min and reperfused for 180 min. Then the infarct size was calculated. The cardiomyocytes were morphologically observed and ECG and hemodynamics were monitored on continuous basis. Acid-base balance was measured during procedure. Our results showed that the infarct size was (48.5+/-11.5)% of the risk area in the control group and (42.4+/-7.9)% in group C (P>0.05). Mean infarct size was significantly smaller in group B (34.5%+/-9.4%) (P<0.05 vs control group) and group A (31.0%+/-9.1%) (P<0.01 vs control group). It is concluded that HA-preconditioning can effectively protect the myocardium.
Acidosis, Respiratory/*physiopathology ; Hypercapnia/*physiopathology ; Ischemic Preconditioning, Myocardial/*methods ; Myocardial Reperfusion Injury/*prevention & control ; Random Allocation

Objective To construct a lentiviral vector of RNA interference (RNAi) of PKCγ gene. Methods The effective sequence of siRNA targeting PKCγ gene was confirmed in our previous study. The complementary DNA containing both sense and antisense oligo DNA of the targeting sequence was designed, synthesized and cloned into the pGCSIL-GFP vector, which contained U_6 promoter and green fluorescent protein (GFP) . The resulting lentiviral vector containing PKCγshRNA was named lentivinis RNAi vector of PKCγ, and it was confirmed by realtime PCR and sequencing. 293T cells were cotransfected with lentiviral vector pGCSIL-CTP, pHelper 1.0 and pHelper 2.0. All virus stocks were produced by calcium phosphate-mediated transfection. The titer of virus was tested according to the expression level of GFP. Results PCR and DNA sequencing demonstrated that the lentivirus RNAi vector of PKCγ producing PKCγshRNA was constructed successfully. The titer of concentrated virus was 1 ×10~9 TU/ml. Conclusion The lentivinis RNAi vector of PKCy was constructed successfully.

Objective To evaluate the role of silent information regulator 1 (SIRT1) signaling pathway in endotoxin-induced acute lung injury (ALI) in rats.Methods Ninety-six clean-grade healthy male Sprague-Dawley rats,aged 4 weeks,weighing 160-180 g,were divided into 4 groups (n=24 each) using a random number table method:control group (group C),ALI group,ALI + SIRT1 agonist SRT1720 group (group SRT),and ALI + SIRT1 inhibitor EX527 group (group EX).ALI was induced by injecting lipopolysaccharide (LPS) 5 mg/kg (diluted to 0.5 ml with 0.9％ normal saline) in ALI,SRT and EX groups.SRT1720 10 mg/kg was injected via the tail vein,and 30 min later ALI model was established in group SRT.EX527 1 μg/kg was injected via the tail vein,and 30 min later ALI model was established in group EX.Blood samples were collected from the abdominal aorta at 6,24 and 48 h after LPS injection for blood gas analysis,rats were then sacrificed and lungs were removed for determination of wet to dry weight ratio (W/D ratio) and expression of SIRT1,nuclear factor kappa B p65 (NF-κB p65),interleukin-6 (IL-6) and IL-1β protein and mRNA (by Western blot or real-time polymerase chain reaction) and for examination of pathological changes of lung tissues (with a light microscope).Results Compared with groups C,PaO2 was significantly decreased,and PaCO2 and W/D ratio were increased at each time point after LPS injection in ALI,SRT and EX groups,the expression of SIRT1 protein and mRNA was significantly down-regulated,and the expression of NF-κB p65,IL-6 and IL-1β protein and mRNA was upregulated at each time point after LPS injection in ALI and EX groups,and the expression of SIRT1,NFκB p65,IL-6 and IL-1β was significantly up-regulated at each time point after LPS injection in group SRT (P＜0.05).Compared with group ALI,PaO2 was significantly increased,PaCO2 and W/D ratio were decreased,the expression of SIRT1 protein and mRNA was up-regulated,the expression of NF-κB p65,IL-6 and IL-1β protein and mRNA was down-regulated at each time point after LPS injection (P＜0.05),and the pathological changes were significantly attenuated in group SRT,and no significant change was found in the parameters mentioned above at each time point after LPS injection in group EX (P＞0.05).Conclusion Inhibited SIRT1/NF-κB signaling pathway is involved in endotoxin-induced ALI in rats.

This study observed the protective effect of hypercapnic acidosis preconditioning on rabbit heart suffered from ischemia-reperfusion injury. Hypercapnic acidosis was established in animals with mechanical hypoventilation before ischemia-reperfusion. Thirty-two rabbits were randomly divided into 4 groups, with each having 8 aminals in term of the degree of acidification: hypercapnic acidosis group A (group A), hypercapnic acidosis group B (group B), hypercapnic acidosis group C (group C), ischemia and reperfusion group (group IR). Animals in group IR were ventilated normally (tidal volume: 15 mL/kg, breathing rate 35 bpm). The PETCO2 was maintained at the level of 40-50 mmHg for 30 min. Animals in groups A, B, C received low-frequency, low-volume ventilation to achieve hypercarbonic acidosis and the target levels of PETCO2 were 75-85,65-75, 55--65 mmHg,respectively, with levels being maintained for 5 min. The animals then were ventilated normally to lower PETCO2 to 40-50 mmHg. The left anterior branch artery of all the animals was ligated for 30 min and reperfused for 180 min. Then the infarct size was calculated. The cardiomyocytes were morphologically observed and ECG and hemodynamics were monitored on continuous basis.Acid-base balance was measured during procedure. Our results showed that the infarct size was (48.5±11.5)% of the risk area in the control group and (42.4+7.9)% in group C (P>0.05). Mean infarct size was significantly smaller in group B (34.5%_+9.4%) (P<0.05 vs control group) and group A (31.0%±9.1%) (P<0.01 vs control group). It is concluded that HA-preconditioning can effectively protect the myocardium.