Effect of rosiglitazone on myocardial energy substrate utilization in type 2 diabetic rats

AIM: To study the effect of rosiglitazone (RSG) to improve insulin sensitivity on myocardial energy substrate utilization as well as the cardiac function in a rat model of type 2 diabetes mellitus. METHODS: Sprague-Dawley rats were conducted into three groups: chow-fed rats were fed with normal chow (12% of calories as fat); fat-fed/STZ rats were fed with high-fat diet (40% of calories as fat) for 4 weeks and then injected with streptozotocin 35 mg/kg intraperitoneal; fat-fed/STZ/RSG rats were fat-fed/STZ rats treated with rosiglitazone (3 mg·kg-1·d-1) for 2 weeks. A cannula connected to a passive transducer was inserted the heart for the measurement of the cardiac function including heart rate (HR), left ventricular end-diastolic pressure (EDP) and ±dp/dtmax. Then the isolated hearts were mounted onto a Langendorff perfusion apparatus to perfuse with Krebs-Henseleit buffer in the presence of 5 mmol/L glucose and 0.4 mmol/L ［3H］ labelled palmitate. Glucose uptake and ［3H2O］ collection were measured to evaluate the rate of carbohydrate and fatty acid oxidation. RESULTS: Compared with the chow-fed rats, fat-fed/STZ rats had a significantly depression of glucose uptake in the hearts ［(54.7±6.2 vs 69.0±5.7) μmol·g-1 dry weight, P<0.01］ after 30 min perfusion. The oxidation of glucose and palmitate were 18% and 82%, respectively. Paralleling the reduction was a change of EDP ［(14.3±1.8 vs 10.5±1.1) mmHg, P<0.05］ and -dp/dt ［(550±57 vs 650±42) mmHg/s, P<0.01］, indicating a impaired left ventricular diastolic function. In the hearts subjected to fat-fed/STZ group, rosiglitazone treated for 2 weeks resulted in a elevated level of glucose uptake ［(63.5±6.4 vs 54.7±6.2) μmol·g-1 dry weight, P<0.05］. A protective role of the ventricular function ［EDP decreased from （14.8±1.9） to （11.0±0.8） mmHg/s and -dp/dtmax increased from （558±60） to （629±51） mmHg/s, P<0.05］ were observed. CONCLUSIONS: Our study indicates that there is a depression of glucose oxidation and at increase in fatty acid oxidation in type 2 diabetic hearts. Elevation of insulin sensitivity using rosiglitazone increases the myocardial glucose metabolism and shows a benefitial result to heart functions.     

Effects of botulinum toxin-A in lower esophageal sphincter in cats

AIM: To investigate the effect of botulinum toxin-A (BTA) on lower esophageal sphincter (LES) after BTA injection into the LES of cats, and then LES pressure, content of Ach and AchE activity were determined to provide scientific proof to treat achalasia with BTA. METHODS: LES pressure was tested on 20 cats. BTA was endoscopically injected circumferentially into the LES in 10 cats, and saline injection served as control (10 cats). One week later, LESP was measured again. Then in vitro, LES samples were gathered. Contents of acetylcholine and cholinesterase activity were determined. By means of Karnovsky-Roots technique, ultrastructure of nerve terminal and vesicles containing Ach were studied under light and electronic transmission microscopes after LES was cut into ultraslices. RESULTS: (1) The LES pressure (LESP) in BTA-treated cats was obviously weakened ［(28.17±3.55) mmHg vs (9.93±1.06) mmHg, P<0.01］ and LESP in control group didnt change ［(28.60±2.79) mmHg vs (26.93±2.05) mmHg, P>0.01］. (2) Contents of LES acetylcholine in BTA-treated cats remarkably decreased, compared with control group ［(75.48±4.67) mg/g vs (93.03±4.65) mg/g, P<0.01］. Consequently, LES acetylcholinesterase activity in BTA-treated cats also apparently decreased, compared with control group ［(38.20±2.17) 103 U/g vs(69.88±6.73) 103 U/g, P<0.01］. (3) The colours of motor end plate fainted away and the number of which became small under light microscopy. The vesicles containing Ach and AchE-positive reactant in the nerve terminal reduced distinctly under the electronic microscopy. CONCLUSION: When BTA is injected into LES, LESP decreases significantly. The reason may be that BTA destroys or inhibits the vesicles of the cholinergic nerve terminal, and as a result, the contents of Ach and AchE activity are evidently reduced.     

早熟大粒无核葡萄新品种‘超级无核’

 ‘超级无核’葡萄系从美国引进葡萄新品种‘Superior Seedless’优选单株培育出的优良品种。无核、大粒、早熟、优质、早实、丰产、生长势强健、耐病、耐不利栽培条件, 是适合高温、高湿、少日照地区栽培的无核葡萄新品种。     

Effect of atorvastatin on blood pressure in spontaneously hypertensive rats

AIM: To explore the mechanisms underlying the effect of atorvastatin on blood pressure in spontaneously hypertensive rats (SHR). METHODS: The effects of atorvastatin on plasma endothelin-1, aortic nitric oxide synthase, aortic smooth muscle cell (ASMC) apoptosis and p27 expression in SHR were evaluated. 12 eight-week-old SHR were randomized into atorvastatin group (ATV, n=6) and SHR group (n=6). 6 age-matched normotensive Wistar-Kyoto rats (WKY) were served as controls. 50 mg·kg-1·d-1 of atorvastatin was administered to ATV by gavage for 10 weeks. Serum cholesterol and triglycerides were measured, and systolic blood pressure of caudal artery was examined. Plasma endothelin-1 and nitric oxide synthase activity of aortic tissue were measured. ASMC apoptosis rate was detected by TUNEL technique, and positive expression rate of P27 in ASMC was analyzed. RESULTS: After 10 weeks, systolic blood pressure in ATV was significantly lower than that in SHR ［(134.17±3.60）mmHg vs （173.33±3.78）mmHg, P<0.01］. Compared with SHR, serum cholesterol and triglycerides were significantly lower (P<0.01, P<0.01) in ATV. Additionally，atorvastatin significantly decreased plasma endothelin-1 ［(130.04±40.07）ng/L vs （196.74±59.69）ng/L, P<0.05］ and increased nitric oxide synthase activity in aortic tissue ［(0.189±0.040）kU/g protein vs (0.124±0.057)kU/g protein, P<0.01］, compared with SHR. ASMC apoptosis rate was higher in ATV than that in SHR (16.94%±3.08% vs 9.01%±2.36%, P<0.01). Compared with WKY, positive expression rate of p27 in ASMC from ATV was higher (33.02%±5.01% vs 24.25%±4.41%, P<0.05), whereas that was lower in SHR (16.08%±7.09% vs 24.25%±4.41%, P<0.01). CONCLUSION: Atorvastatin may reduce the plasma endothelin-1， up-regulate nitric oxide synthase activity and ASMC P27 expression and facilitate ASMC apoptosis，which may effectively reduce blood pressure in SHR.     

Quantitive analysis of mitochondrial DNA deletion in mice with viral myocarditis

AIM: To elucidate the role of mitochondrial DNA (mtDNA) deletion in the pathogenesis of viral myocarditis in mice. METHODS: 50 BALB/c mice were divided into two groups randomly. 40 were experimental group, each of them was injected 0.1 mL Eagle liquids with CVB3 (TCID50=108) intraperitoneally. Another 10 mice were given equal volume Eagle liquids as control group. Cardiac functions in vivo and mtDNA3867 deletion rate in myocytes were detected separately at the day 3, 11 and 24 after injection. The correlation of mtDNA3867 deletion rate to cardiac functions was analyzed using Spearman method. RESULTS: At the day 3 after injection, mtDNA3867 deletion rate in experimental group was 8.3 times higher than that in control group ［(0.01970±0.00118)% vs (0.00211±0.00032)%，P＜0.05］. The -dp/dtmax, which reflects cardiac diastolic function, was also damaged (P＜0.05). At the day 11 after injection, mtDNA3867 deletion rate in experimental group was 14.6 times higher than that in control group ［(0.03292±0.00308)% vs (0.00211±0.00032)%，P＜0.05］. Cardiac functions were injured to the most extent in experimental mice as compared with the control group ［LVPSP: (79.63±4.69)mmHg vs (99.64±8.21) mmHg, P＜0.01; +dp/dtmax: (3 088.14±267.86) mmHg/s vs (4 903.24±668.36) mmHg/s, P＜0.01; -dp/dtmax: (－2 463.29±359.92) mmHg/s vs (－4 172.85±595.97) mmHg/s, P＜0.01］. At the day 24 after injection, mtDNA3867 deletion rate and cardiac functions was still significantly higher in CVB3 injected mice. Correlation analysis showed that mtDNA3867 deletion rate was negative correlation to LVPSP and +dp/dtmax, and positive correlation to -dp/dtmax. The correlation coefficient was -0.66, -0.79 and 0.80, respectively. CONCLUSION: mtDNA3867 deletion in myocytes might play a role in the pathogenesis of viral myocarditis.     

Effects of hypotensive or aggressive resuscitation on tissue ATPase activity in pregnant rabbits with uncontrolled hemorrhagic shock

AIM: To compare the effects of hypotensive and aggressive resuscitation strategies on blood loss, fluid requirements, hematocrit (Hct), tissue Na＋-K＋-ATPase and Ca2＋-Mg2+-ATPase activities in a clinically relevant model of uncontrolled hemorrhagic shock in pregnancy rabbits. METHODS: Thirty anesthetized New Zealand white rabbits at mid and late gestation underwent uncontrolled hemorrhagic shock by transecting a small artery of mesometrium, followed by bleeding via carotid artery to mean arterial pressure (MAP) of 40-45 mmHg. Animals were randomly divided into five groups (n=6 each): sham shock (SS); shock without resuscitation (SH); aggressive resuscitation in pre-hospital phase with 4 mL/kg normal saline, followed by Ringer’s solution to MAP of 80 mmHg (NS), hypotensive resuscitation with 4 mL/kg of normal saline (NH) or hypertonic hydroxyl ethyl starch (7.5% NaCl + hydroxy ethyl starch, HHES, HHH) followed by Ringer’s solution to MAP of 60 mmHg. Finally, all the resuscitated animals received hemorrhage controlled and fully resuscitated to MAP of 80 mmHg. At the end of the experiment, survivors were sacrificed, skeletal muscle, cardiac muscle, liver, kidney, lung and ileum were harvested for determination of Na＋-K＋-ATPase and Ca2＋-Mg2+-ATPase activities. RESULTS: Total blood loss and infused volume were compared between NH［(4.3±0.2)mL/kg, (47.2±4.1)mL/kg］ and HHH［(4.1±0.3)mL/kg,(44.9±4.3)mL/kg］ groups, both were significantly less than NS［(5.5±0.2)mL/kg, (65.5±3.8）mL/kg］　group. Hct in NH (21.0%±2.1%) and HHH (21.5%±1.8%) were significantly higher than NS (14.2%±1.5%) and SH (12.5%±1.4%).Tissue Na＋-K＋-ATPase and Ca2＋-Mg2+-ATPase activities were stimulated in all shock groups. Na＋-K＋-ATPase in skeletal muscle, cardiac muscle, liver, kidney was significantly lower in the NH (5.42±1.41, 4.54±2.01, 4.13±0.62, 3.42±0.84) and HHH (3.97±0.91, 2.94±0.66, 3.22±1.42, 3.03±0.53) than that in NS (7.34±1.41, 6.23±1.53, 6.11±0.97, 5.82±0.69) and SH (9.11±0.52, 8.40±1.08, 7.04±1.13, 6.55±1.45). CONCLUSION: Hypotensive resuscitation with normal saline or HHES reduces blood loss, decreses total infused volume, leads to higher hematocrit and finally alleviates metabolism derangement after uncontrolled hemorrhagic shock.     

Restoration of cardiac function in failing beagle hearts by recombinant adeno-associated viral gene transfer of sarcoplasmic reticulum Ca2+-ATPase

AIM: Abnormal Ca2+ homeostasis is one basic cause of heart failure. Studies have recently shown that overexpression of sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA2a) by adenoviral/adeno-associated viral gene transfer restores contractile function ex vivo and in murine or rabbit models. We therefore hypothesized that an increase in SERC A2a protein will improve cardiac function in a pacing-induced big animal model of heart failure.METHODS: 17 beagles were randomized into control group (CG, n=4) and chronic heart failure group (n=11). Four weeks after right ventricular rapid pacing (230 beats/min), 11 beagles all got heart failure (documented by >29.3% decrease in ejection fraction). 4 of 11 were used as heart failure group (HF, n=4). 9 HF beagles were randomized to receive either a recombinant adeno-associated viral carrying the SERCA2a gene (HF+SERC A2a, n=5) or the reporter gene enhanced green fluorescent protein (HF+EGFP, n=4) by thoracotomy. All HF beagles paced by 180 beats/min in order to maintain failing state. Thirty days after infection, parameters of systolic and diastolic function were measured by doppler echocardiography and hemodynamic monitor in all beagles.RESULTS: At 30 days after gene transfer, symptoms of HF+SERCA2a dogs improved. Echocardiogram parameters were superior to those in HF+EGFP group (P<0.05). Cardiac hemodynamic parameters of HF+SERCA2a dogs strikingly improved: LVSP, +dp/dtmax and -dp/dtmax increased, mean value increased respectively 54.12％［(214.72±31.74) mmHg vs (139.32±36.79) mmHg］, 146.81％［(6 779.43±217.58) mmHg/s vs (2 746.85±931.2) mmHg/s］ and 71.52％［(-4 341.42±322.02) mmHg/s vs (-2 531.14±616.15) mmHg/s］; LVEDP lowered 63.43％［(21.86±6.95) mmHg vs (59.78±6.92) mmHg］ compared with the dogs in HF+EGFP group. No significant difference in all parameters compared with those of control group was observed. Under laser confocal microscopy, widespread green fluorescence was observed in the myocardial frozen section of dogs in HF+EGFP group. CONCLUSION: These results support the hypothesis that overexpression of SERCA2a improves cardiac function in big animal model of chronic heart failure. The study demonstrates that gene transfer of SERCA2a into cardiac with recombinant adeno-associated viral vector is a prospective therapy methods.     

Effect of γ radioactive stent on proliferation and apoptosis of smooth muscle cells

AIM: To observe effect of γ radioactive ［103Pd］ stent on the proliferation and apoptosis of smooth muscle cells, the mechanism of radioactive stent preventing in-stent restenosis was explored. METHODS: Fifty male New Zealand rabbits were randomized into stent group and ［103Pd］ stent group. Control group was set up. The materials were harvested on 3, 7, 14, 28, 56 days after operation and the following investigation were carried out, including pathomorphology, immunohistochemistry, apoptosis (TUNEL) and in situ hybridization studies.RESULTS: ① The severity of the stenosis in ［103Pd］ stent group was less severe than that in stent group. It was most obvious on 56 th day (P<0.01). ② The expression of proliferating cell nuclear antigen(PCNA) of ［103Pd］ stent group was lower than that in stent group on 3 to 28 days. It was most obvious on 7th day, 16.35%±0.79% vs 24.36±0.55% (P<0.01). ③ TUNEL method showed that the ［103Pd］ stent group had much more apoptosis of VSMC than that in stent group. The highest rate of apoptosis appeared on day 7, 14.72%±0.53% vs 12.42%±1.13% (P<0.01). ④ By calculating the ratio of PCNA/apoptosis (P〖KG*6〗∶〖KG-*2〗A), a much lower ratio was seen in ［103Pd］-stent groups than that in stent group at 3 to 28 days. There was significant statistic difference (P<0.05). ⑤ For bcl-2/bax ratio, the result in ［103Pd］-stent group was lower than that in stent group at 3 to 28 days. There was significant statistic difference (P<0.05).CONCLUSION: γ radioactive stent inhibits the proliferation and accelerates apoptosis of injured media vascular smooth muscle cells. It decreases the ratio of proliferation to apoptosis and relieves the severity of restenosis.     

Development and evaluation for volume overload-induced and pressure overload-induced cardiac hypertrophy in rats

AIM: To compare the evaluations for the structure and function of the hypertrophic hearts induced by volume overload or pressure overload in rats. METHODS: Volume overload-induced cardiac hypertrophy was established by abdominal aortacaval fistula (ACF) and pressure overload-induced cardiac hypertrophy was developed by constriction of aorta (CA). The cardiac structure and function were analyzed by echocardiography, hemodynamic determination, heart weight measurement and histological examination. RESULTS: Heart weight of rats in all the operated groups was increased compared to the sham-operated groups. In 1-week ACF group, the internal diameter ［(0.67±0.03)cm vs (0.60±0.02)cm, P<0.01］ and volume of left ventricle increased ［(0.69±0.10)mL vs (0.50±0.04)mL, P<0.01］，relative wall thickness (RWT) decreased (0.46±0.05 vs 0.55±0.05, P<0.01), compared with the sham-operated group. In 1-week CA group, interventricular septal thickness ［(0.20±0.03)cm vs (0.16±0.02)cm, P<0.05］, left ventricular posterior wall thickness ［(0.20±0.03)cm vs (0.16±0.02)cm, P<0.01］, RWT (0.71±0.17 vs 0.56±0.12, P<0.05) and +dp/dtmax (4 886±1 304 vs 3 674±325, P<0.05) were all increased compared with the sham-operated group. In 2-week-groups, these parameters changed more significiantly. CONCLUSION: Cardiac structure and function could be evaluated by echocardiography and hemodynamic determination. RWT is a sensitive index for the cardiac hypertrophy induced by both volume overload and pressure overload.     

Meconium induces formation of nitrotyrosine and expression of inducible nitric oxide synthase in the rat lung

AIM: To evaluate the contribution of inducible nitric oxide synthase (iNOS) and nitrotyrosine to acute lung injury (ALI) in rats with meconium aspiration. METHODS: 16 health male Sprage-Dawley rats were randomized to control group and meconium group, followed by intratracheally administration of 1 mL/kg saline or 1 mL/kg 20% human newborn meconium suspension. The animals were killed after 24 h of treatment. The measurements included bronchoalveolar lavage fluid (BALF) cell count, pulmonary myoloperoxidase (MPO) activity and nitric oxide (NO) level. Western bloting was used to determine the expression of pulmonary nitrotyrosine-a specific “footprint” of peroxynitrite and iNOS. RESULTS: Compared to control group, the rats in the meconium group had increased BALF cell counts ［(4.04±1.01)×109cells/L vs （0.53±0.19)×109cells/L］, pulmonary MPO activity ［(1.49±0.22）U/g wet lung tissue vs (0.62±0.16) U/g wet lung tissue］, NO level ［(12.77±5.00） mmol/g protein vs （4.89±1.32) mmol/g protein］, increased expression of nitrotyrosine and iNOS (0.46±0.19 and 1.49±0.60 vs 0.15±0.04 and 0.09±0.04, respectively), all P<0.01. CONCLUSIONS: Meconium results in an increase in expression of pulmonary iNOS, leading to over production of NO and nitrotyrosine, which may be of pathogenic importance in the ALI with meconium aspiration.     

Increased effects of M-CSF and staurosporine on the binding of macrosialin of MPM to ox-LDL

AIM: To investigate the effects of human recombininant macrophage colonly-stimulating factor (M-CSF) and protein kinase C inhibitor, staurosporine (STA), on the binding of macrosialin of the mouse peritoneal macrophages (MPM) to ox-LDL. METHODS: MPM was disrupted by using ultrasonic pulse method after preincubation of M-CSF and STA. The plasma membrane proteins were separated by SDS-PAGE under nonreducing condition. The separated proteins were transferred to a nitrocellulose membrane. The ligand blotting and immunoblotting were used. The effects of M-CSF and STA on expression of cell surface receptor were observed by means of autoradiography. RESULTS: Preincubation with medium containing neuraminidase dramatically decreased the binding of macrosialin to ［125I］-ox-LDL ［(2.45±0.46) μg/g cell protein vs (58.38±1.78) μg/g cell protein］. When pretreated with M-CSF, macrosialin bound predominantly to ox-LDL. The Bmax of ［125I］-ox-LDL to macrosialin increased when macrophages were treated with M-CSF ［(322.77±12.54) vs (453.59±15.39) μg/g］. Meanwhile, the dissociation constant of treated group showed little changes ［(29.06±2.87) vs (28.26±4.10) mg/L］. The similar result was found when macrosialin was pretreated with STA, a protein kinase C inhibitor. The Bmax of ［125I］-ox-LDL to macrosialin increased ［(264.76±11.29) vs (362.40±15.31) μg/g］. The dissociation constant of treated group showed little changes either ［(17.43±2.98) vs (15.10±2.67) mg/L］. CONCLUSION: The results indicate that M-CSF and STA enhance the binding of macrosialin to ox-LDL by increasing the cellular surface receptor number.     

Role of vascular remodeling for urotensin Ⅱ in rat thoracic aorta after balloon injury

AIM: To explore the possible effect of UII in the process of remodeling after vascular injury. METHODS: The rat model of balloon injury in thoracic aorta was established. Male rats were randomized to 4 groups (n=5), including sham injury group, injury group, UII group (UII pumped into the rats after thoracic aorta balloon injury at 1.0 nmol·kg-1·h-1) and urantide group (urantide pumped into the rats after thoracic aorta balloon injury at 10 nmol·kg-1·h-1). At 21 days, the thoracic aortas were taken out to measure the changes of pathology, the expression of UII, the proliferation of VSMC and the expression of collagen. RESULTS: (1) At the 21 days after operations, the systolic blood pressure was higher in UII group than that in injury group ［(140.0±10.0) mmHg vs (132.0±3.4) mmHg, P>0.05］. The systolic blood pressure was also obviously higher than that in urantide group ［(140±10.0) mmHg vs (128.0±2.4) mmHg, P<0.05］. (2) Urotensin Ⅱ was expressed strongly in the injured area after thoracic aorta injury. (3) In contrast to injury group, the intimal thicken in urotensin Ⅱ group enhanced, the decrease in lumen area was marked (0.13±0.05 vs 0.07±0.02, P<0.05), the cell proliferation index was markedly increased (0.74±0.16 vs 0.40±0.11, P<0.01), and the expression of collagen was also markedly increased (counted as IOD, 318±127 vs 78±26, P<0.01). (4) In contrast to injury group, the decrease in lumen area was not abolished (0.09±0.03 vs 0.07±0.02, P>0.05) after chronic infusion of urotensin Ⅱ receptor antagonist urantide, the cell proliferation index was markedly increased (0.73±0.15 vs 0.40±0.11, P<0.01) and the expression of collagen was not statistically increased (counted as IOD, 200±79 vs 78±26, P>0.05). CONCLUSION: Urotensin Ⅱ expresses strongly in the myointimal cells after thoracic aorta injury in rat. The extra UII enhances the proliferation of VSMC and expression of collagen in the myointimal, increases the stenosis of injured vasculature, indicating that UII might take part in the process of repairing after vessel injury.     

Hepatocyte protection of ethyl pyruvate in septic mice

AIM:To study the protective effect of ethyl pyruvate (EP) on hepatocytes in septic mice. METHODS:The cecal ligation-perforation was made in mice as septic model. Ringers ethyl pyruvate solution (REPS) and Ringers lactic solution (RLS) were used to resuscitate septic mice. Anti-oxidative capacity of hepatic tissue and liver function were detected in different groups. RESULTS:Anti-oxidative capacity in septic mice was significantly lower than that in sham group (P<0.01). EP promoted the anti-oxidative capacity of hepatic tissue in septic mice. Malondialdehyde level was lower in REPS group than that in RLS group ［(48.18±5.98) μmol·g-1 protein vs (78.34±11.16) μmol·g-1 protein］, superoxide dismutase ［(5.19±1.41)103 U/g protein vs (3.20±1.08)103 U/g protein］ and total anti-oxidative capacity ［(7.02±1.79)103 U/g protein vs (4.77±1.35)103 U/g protein］ level were higher in REPS group than those in RLS group (P<0.01). Alanine aminotransferase in REPS group were lower than that in RLS group ［(210.06±23.36) U vs (458.86±51.55) U, P<0.01］. CONCLUSION:Ethyl pyruvate is an effective anti-oxidant in septic mice, which significantly increases the anti-oxidative capacity in hepatic tissue and ameliorates liver function.     

Increased central reactive oxygen species mediate the attenuated baroreflex function in heart failure

AIM: To determine the effect of reactive oxygen species on the baroreflex and to investigate the intracellular mechanism responsible for baroreflex dysfunction in the heart failure state.METHODS: In the rat model of cardiomyocytes infarct induced heart failure, baroreflex function was evaluated by measuring the relationship between renal sympathetic nerve activity(RSNA)responses and change of blood pressure by intravenous injection of nitroglycerin and phenylephrine. Alteration in baroreflex function was measured under the different reactive oxygen species(ROS)level induced by intracerebroventricular administration of several chemicals. RESULTS: (1)The range of RSNA response, average slope and maximum gain of baroreflex function curve were(92.2±9.9) mmHg,(0.07%±0.01%)/mmHg and(1.20%±0.10%)/mmHg, respectively, in CHF rats, which were significantly lower than those in sham rats(65.6±7.4) mmHg,(0.13%±0.02%)/mmHg and(3.00%± 0.20%)/mmHg(P<0.01).The minimum RSNA of baroreflex curve was higher in CHF rats than that in sham rat［(21.6%±4.8%)vs(7.5%±2.1%), P<0.01］.(2)Intracerebroventricular(icv)infusion of superoxide scavenger tempol and NADPH oxidase inhibitor apocynin significantly improved the blunted baroreflex in CHF rats. On contrast, icv administration of superoxide dismutase inhibitor diethyldithiocarbamate(DETC)decreased baroreflex function in sham rats.(3)The superoxide production in the hypothalamus of CHF rats was higher than that in sham rats［(73.9±9.8)RLU·5min-1·mg-1vs(40.6±7.1)RLU·5min-1·mg-1, P<0.01］.(4)Protein expression of NADPH oxidase subunits gp91phox in the paraventricular nucleus of the hypothalamus were increased by 1.3 fold in CHF rats than that in sham rats. CONCLUSION: Elevated intracellular ROS in the hypothalamus plays an important role in the attenuation of baroreflex function in the heart failure state and results from upregulation of NADPH oxidase protein expression.     

COX-2 inhibitor protects rat heart against oxidative stress through a pathway independent of cyclooxygenase

AIM: To investigate whether nimesulide ［a selective cyclooxygenase 2 (COX-2) inhibitor］ and piroxicam (an inhibitor of COX-1) protect the rat hearts against oxidative stress induced by hydrogen peroxide,superoxide anion or hydroxyl free radical.METHODS: Cardiac contractility,lactate dehydrogenase (LDH) and malondialdehyde (MDA) were analyzed by the Langendorff method in isolated rat hearts.Production of 6-Keto-PGF1α,a marker of COX activity,was measured in isolated rat hearts.RESULTS: Rat hearts were exposed to hydrogen peroxide (H₂O₂),pyrogallol (which produced superoxide anion) or Vit C+Fe2+ (which produced hydroxyl free radical) for 10 min followed by reperfusion for 30 min.H₂O₂ decreased cardiac contractility and increased LDH release,which was inhibited by nimesulide (3 mg/kg) ［LVDP 72%±10% vs 61%±11%,LDH （5.5±2.5）U/L vs （8.0±2.1）U/L,P<0.05］.Piroxicam (3 mg/kg) increased systolic function (LVDP 73%±10% vs 61%±11%,P<0.05),but exacerbated diastolic function ［LVEDP （29.00±5.61）mmHg vs （23.16±3.57） mmHg,P<0.01］ in H₂O₂ treated rat hearts.Nimesulide also protected rat hearts against superoxide anion and hydroxyl free radical injury.Nimesulide and piroxicam had no effect on the content of 6-Keto-PGF_1α in rat hearts.Mitochondrial ATP sensitive potassium channel (mitoK_ATP) inhibitor 5-HD blocked the improvement of contractility (LVDP and ±dp/dt_max) induced by nimesulide in H₂O₂ treated rat hearts (53%±12% vs 69%±3%,58%±11% vs 72%±7% and 37%±8% vs 51%±4% respectively,P<0.01).CONCLUSION: The results suggests that COX-2 inhibitor nimesulide can protect rat hearts against oxidative injury.The protection is independent of COX activity.Activation of mitoK_ATP may be involved in nimsulide-induced cardioprotection in rat hearts.     

Genistein downregulates survivin gene expression and induces apoptosis in hepatocellular carcinoma HepG2 cells

AIM: To probe into the role of 1, 4, 5-trisphosphate inositol (IP3) and survivin protein in apoptosis of HepG2 cells induced by genistein. METHODS: HepG2 cells were treated with 60 μmol/L genistein for 12 h, 24 h, 48 h and 72 h. IP3, survivin and apoptosis rate were assayed by IP3-［3H］ Birtrak assay, Western blotting and flow cytometry, respectively. RESULTS: IP3 in groups incubated for 12 h, 24 h, 48 h and 72 h with 60 μmol/L genistein were significantly lower than that in control (P<0.01) ［(12.0±1.4) pmol/106cells, (7.5±0.8) pmol/106 cells, (5.6±0.5) pmol/106cells, (3.3±0.6) pmol/106 cells， vs (29.2±0.6) pmol/106 cells］. V-survivin/ V-β-actin, which was the gray degree multiply area of survivin/the gray degree multiply area of β-actin in groups incubated for 12 h, 24 h, 48 h and 72 h with 60 μmol/L genistein, were significantly lower than that in control (P<0.01) ［（0.36±0.13, 0.33±0.03, 0.23±0.04, 0.18±0.04）， vs 0.63±0.06］. The apoptosis rate in groups incubated with 60 μmol/L genistein for 24 h, 48 h and 72 h was significantly higher than that in control （P<0.01） ［(7.4%±0.5%, 20.5%±2.0%, 30.7%±1.6%) vs 2.6%±0.1%］. CONCLUSION: Genistein induces apoptosis in HepG2 cells by reducing IP3 production and survivin protein expression.     

Effect of NAC on oxidant stress and apoptosis in the hippocampal CA1 region of rats exposured to chronic intermittent hypoxia

AIM: To investigate the effect of N-acetylcystein (NAC) on oxidant stress, neuron apoptosis in the hippocampal CA1 region of rats exposured to chronic intermittent hypoxia (CIH). METHODS: 30 healthy male Wistar rats were randomly divided into three groups of 10 each, a CIH group, a NAC therapeutic group and a control group. The levels of MDA and SOD were detected by colorimetric method. Immunohistochemistry was used to examine the expression of p-JNK and TUNEL was used to detect the neuron apoptosis in the hippocampal CA1 region. RESULTS: The level of MDA in NAC group were lower than that in CIH group［(1.71±0.43) μmol/g protein vs （1.37±0.26) μmol/g protein, P<0.05)］. The activity of SOD in NAC group was higher than that in CIH group［(44.94±14.01) 103 NU/g protein vs(57.66±14.07) 103 NU/g protein, P<0.05)］. The expression of p-JNK protein and the apoptotic indices ［(0.39±0.16), (0.20±0.11)］ in NAC group were significantly lower than those in CIH group ［(0.53±0.10), (0.32±0.18), all P<0.05］. CONCLUSION: NAC protects hippocampal neuron from apoptosis by suppressing the oxidant stress in the hippocampal CA1 region and inhibiting the activation of JNK signaling pathway.     

Sodium valproate induces cycle arrest,apoptosis and elevates p21WAF1 mRNA expression in chronic myeloid leukemia cell line K562

AIM:To investigate the effects of sodium valproate (VPA) on the cell cycle and apoptosis of chronic myeloid leukemia cell line K562, and to explore the possible mechanisms. METHODS:K562 cells were treated with VPA. Cell cycle and apoptosis were analyzed by flow cytometry. The expression of p21WAF1 mRNA was detected by RT-PCR. RESULTS:After treatment with VPA, cell cycle was arrested obviously at G0/G1 phase ［(82.30±9.41)% vs (40.13±2.12)%, P<0.05］. The apoptotic rate was significantly higher in the cells treated with VPA than that in untreated cells ［(11.47%±0.25%) vs (4.77%±0.40%), P<0.05］. The level of p21WAF1 mRNA was increased ［(1.65±0.91) vs (0.25±0.04), P<0.05］. CONCLUSION:VPA induces elevated expression of p21WAF1 mRNA in K562 cells, resulting in G0/G1 phase arrest and apoptosis in vitro.     

Role of EETs downregulation in obesity-related hypertension induced by a high fat diet

AIM: To study the effect of renal epoxyeicosatrienoic acids (EETs)on juvenile rats with obesity related hypertension induced by high fat diet.METHODS: Sprague-Dawley male rats were fed with high fat diet from 3-week old. The changes of weight and sBP between the rats of high fat diet and normal diet were compared. EETs activity was analyzed with RP HPLC and Western blotting in different parts of kidney.RESULTS: Weight and sBP increased in high fat diet group at the eighth and eleventh weeks ［(328±23)g vs (273.0±21.0)g, (153.0±8.6)mmHg vs (134.0±7.7)mmHg, P<0.05］. No significant change of the EETs activity of renal microvessels between two groups was observed. The EETs activity in cortex and papilla decreased in high fat diet group compared with that in normal diet group ［(75.4±9.2)nmol·g-1·min-1 vs (138.1±10.3)nmol·g-1·min-1, (55.8±6.2)nmol·g-1·min-1 vs (121.6±11.3)nmol·g-1·min-1, P<0.05］, and this was confirmed by Western blotting.CONCLUSION: These results demonstrate that juvenile rats with obesity related hypertension induced by high fat diet might be related to the downregulation of EETs activity in cortex and papilla.     

Effects of M. vaccae on eosinophil apoptosis and Bcl-2 protein expression in lung tissues of asthmatic guinea pigs

AIM: To study the effects of M. vaccae on eosinophil apoptosis and Bcl-2 protein expression in lung tissues of asthmatic guinea pigs. METHODS: 30 guinea pigs were divided into normal saline (NS) group, asthma group and M. vaccae treatment group at random, every group included 10 guinea pigs. Guinea pigs in M. vaccae treatment group were injected intramuscularly with 22.5 μg M. vaccae 10 days before OVA immunization. TdT-mediated dUTP nick end labeling (TUNEL) technique was used to investigate the apoptosis of eosinophils and immunohistochemistry method was used to study the expression of Bcl-2 protein in lung tissues. RESULTS: The apoptosis index (AI) of eosinophils in lung tissues in M. vaccae treatment group was significant higher than that in asthma group ［(23.78±5.42)% vs (4.56±0.68)%, P<0.01］. The mean optical density value of Bcl-2 protein in lung tissues of M. vaccae treatment group was significant lower than that of asthma group ［(1 556.3±492.4) vs (2 321.9±751.2), P<0.05］. CONCLUSION: The apoptosis of eosinophils induced by M. vaccae in lung tissues of asthmatic guinea pigs may be due to the inhibition of Bcl-2 protein expression.