Effects of nitric oxide synthase inhibitor in two-week oral treatment on hyperdynamic circulatory statein cirrhotic rats

AIM:To investigate the ef ects of low dosage of nitric oxide synthase(NOS)inhibitor N^G-nitro-L-arginine methyl ester(L-NAME)in two-week treatment on the hyperdynamic circulatory state in rats with cirrhosis.METHODS:Cirrhosis model was induced in male SD rats by injection of 60%CCl4 oily solution subcutaneously.Cirrhotic rats were treated with L-NAME(0.5 mg kg^-1d^-1)by gavage for two weeks.Mean arterial pressure(MAP), portal pressure(PP), cardiac output(CO), cardiac index(CI), splanchnic vascular resistance(SVR), splanchnic blood flow(SBF)and serum nitrite levels were determined in L-NAME-treated, L-NAME-untreated cirrhotic rats and controls by using 57Co-labled microsphere technique and a fluorometric assay, respectively.RESULTS:Untreated cirrhotic rats had significantly lower MAP, SVR and higher PP, CO, CI, SBF and nitrite concentration than those of the controls(all, P<0 01).In treated cirrhotic rats, L-NAME significantly at enuated the increase of CO, CI, SBF, nitrite concentration and the decrease of MAP and SVR.In treated cirrhotic rats, L-NAME induced a marked decrease of nitrite concentration than untreated cirrhotic rats[(1.471 0.907)mol/L vs(4.204 1.253)mol/L, P<0 01].CONCLUSION:The endogenous NO may play an important role in the changes of hemodynamics pat ern in cirrhosis, andhyperdynamic circulatory state in rats with cirrhosis can be ameliorated by oral two-week administration of lower dose of L-NAME.     

Effects of nitric oxide and endothelin on relaxation and contraction of isolated splanchnic vascular strips in cirrhotic rats

AIM: To investigate the different vasoactive effects of nitric oxide (NO) and endothelin (ET) on splanchnic arterial and venous vessels in cirrhotic rats. METHODS: Cirrhosis was induced in Wistar rats by subcutaneously administration of carbon tetrachloride. Maximal relaxation (Rmax) and contraction (Cmax) to NO and ET were determined in vitro using isolated vascular strips prepared from portal vein (PV) and mesenteric artery (MA) of both cirrhotic and normal rats, and EC50 was calculated for effects of NO and ET, respectively. RESULTS: Rmax of PV and MA to sodium nitroprusside (SNP) (releasing NO) were significantly higher in cirrhotic rats (n=8) than those in normal rats (n=7), and EC50 of NO were dramatically lower in cirrhotic rats than those in control (P<0.05,P<0.01). Cmax of PV and MA to ET were significantly decreased in cirrhotics compared with control, and EC50 of ET were obviously increased in cirrhotic rats compared with normal rats (P<0.05,P<0.01). Furthermore, there were significant differences in Rmax, Cmax and EC50 to NO and ET between PV and MA in both of cirrhotic and normal rats, but these differences in cirrhotics were greater than those in control (P<0.05 or P<0.01). CONCLUSION: There are significant different vasoactive effects of NO and ET on splanchnic arterial and venous vessels in cirrhotic rats, and it may play a crucial role in the pathogenesis of portal hypertension.     

Reversion of the decline of cardiac function in endotoxin shock rats by cholecystokinin octapeptide

AIM: To verify the effect of cholecystokinin octapeptide(CCK-8) on cardiac function in endotoxin shock (ES) rats. METHODS: The rats were divided into four groups:control,lipopolysaccharide(LPS),CCK-8 and CCK-8+LPS. The left ventricle pressure(LVP),the maximal/minimum rate of LVP,heart rate (HR) and mean arterial pressure (MAP) were measured. The activity of superoxide dismutase (SOD),the contents of malondialdehyde (MDA) and nitric oxide (NO) in both serum and myocardium were also measured,respectively. RESULTS: CCK-8 (40 μg·kg^-1, iv) elicited bradycardia in short time and gently increase MAP,LVP and ±LVdp/dt_max. Lipopolysaccharide(LPS, 8 mg·kg^-1, iv) caused a variation in heart rate (HR)(a bradycardia following a tachycardia) and rapid decreases in MAP,LVP and ±LVdp/dt_max. The rapid variation of HR and the decline of MAP,LVP and ±LVdp/dt_max were reversed by pretreatment with CCK-8 in ES rats, but didn't restore to normal. The activity of SOD was increased and the contents of MDA and NO were decreased by pretreatment with CCK-8 in ES rats. CONCLUSION: The decline of cardiac function in ES rats could be reversed by pre-administration of CCK-8 and the decrease in NO production may be one of the mechanisms.     

Effect of Scutellaria barbata flavonoids on abnormal changes of Bcl-2, Bax,Bcl-xL and Bak protein expression in mitochondrial membrane induced by composite Aβ25-35

AIM：To study the abnormalities of Bcl-2, Bax, Bcl-xL and Bax in the cell mitochondrial membrane of cerebral cortex in the rats injected with β-amyloid beta protein 25-35 (Aβ25-35) in combination with aluminum trichloride (AlCl3) and recombinant human transforming growth factor β1 (rhTGF-β1) (composite Aβ25-35) into lateral cerebral ventricle, and to explore the intervention of Scutellaria Barbata flavonoids (SBF). METHODS：The male SD rats were used to establish the neuronal damaged model by receiving injection of RhTGF-β1 1 μL (10 ng) on day 1 of operation, and then from day 2 of operation, intracerebroventricular injection of Aβ25-35 (4 μg/d, consecutive 14 d) in the morning and 1% AlCl3 in the afternoon (3 μL/d, consecutive 5 d). On the day 49 of operation, the successful model rats were randomly divided into model control and 3 doses of SBF groupss. The rats in SBF groups were daily orally administered with SBF at doses of 35, 70 and 140 mg/kg for 36 d. All the rats were decapitated 60 min after the last administration. The protein expression of Bcl-2, Bax, Bcl-xL and Bak in rat cerebral cortex cell mitochondrial membrane was detected by Western blotting. RESULTS：The composite Aβ25-35 dramatically caused decreases in Bcl-2 and Bcl-xL (P<0.05), and increases in Bax and Bak (P<0.01) in rat cerebral cortex cell mitochondrial membrane. However, oral treatment with SBF for 36 d reversed the above disorders induced by composite Aβ25-35. CONCLUSION：The composite Aβ25-35 induces the expression abnormalities of Bcl-2, Bax, Bcl-xL and Bak in mitochondrial membrane and SBF reverses the above disturbances of apoptotic factors.     

The dynamic changes of plasma nitric oxide and endothelin-1 in prehepatic portal hypertension rats

AIM:To observe the dynamic changes of plasma levels of nitric oxide(NO) and endothelin (ET-1) in portal veins of the rats during prehepatic portal hypertension, and investigate the role of them in hyperdynamic circulation.METHODS:The models of prehepatic portal hypertension were established in Sprague-Dawley rats by means of partial portal vein ligation (PVL). The plasma levels of nitrite/nitrate (NO₂^-/NO₃^-) and ET-1 in the portal veins were detected by the method of nitric reductase and radioimmunoassay, respectively. In this study, rats were divided into normal, sham operation (SO) and PVL group. SO and PVL rats were divided into several subgroups according to different time after operations. Meanwhile, the changes of several hemodynamic indexes in these rats were also measured.RESULTS:The levels of NO₂^-/NO₃^- were significantly increased and ET-1 were significantly decreased in rats at different time after PVL compared with normal control, whereas the hemodynamic indexes changed accordingly.CONCLUSION:The portal hypertensive rats are in hyperdynamic circulatory state (HCS). NO and ET-1 may play an important role in the induction and maintenance of HCS.     

Protective effect of ethyl pyruvate on brain tissues in neonatal rats with hypoxic-ischemic brain damage

AIM：To study the effects of ethyl pyruvate (EP) on brain tissues in neonatal rats with hypoxic-ischemic brain damage (HIBD) and its underlying mechanisms. METHODS：A total of 165 seven-day-old Sprague-Dawley (SD) rats were randomly divided into 3 groups：sham operation group (n=43), HIBD group (n=61) and HIBD+EP group (n=61). The rats in HIBD+EP group were intraperitoneally injected with EP (50 mg/kg) 30 min before operation, and once a day after surgery. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in brain homogenate, water content of brain and apoptotic cells in cortex were detected 3 days later. Ischemic and non-ischemic brain tissues were weighed to assess the extent of brain atrophy 14 days later. RESULTS：Higher level of SOD ［(125.78±18.35)×103 U/(g protein)］ and lower level of MDA ［(4.42±1.04) μmol/(g protein)］ in HIBD+EP group than that in HIBD group ［(97.84±15.50)×103 U/(g protein) and (6.02±0.89) μmol/(g protein), respectively］ was observed (P<0.05)．In addition, the water content of ischemic hemisphere was significantly higher than that of non-ischemic one in HIBD group (P<0.05), and was indistinguishable from that of non-ischemic one after EP treatment (P>0.05), indicating the protective effect of EP against brain edema. The apoptotic cells in cortex and hippocampus in HIBD+EP group ［(96.63±10.08)/field and (41.91±9.96)/field, respectively］ were obviously decreased compared with HIBD group ［(111.54±1.64)/field and (51.73±1.77)/field, respectively］, but still higher than those in sham operation group (P<0.05). The atrophy ratio of ischemic hemisphere in HIBD+EP group was (13.25±5.19)%, significantly lower than that in HIBD group ［(20.32±5.10)%, P<0.05］. CONCLUSION：Ethyl pyruvate is neuroprotective against HIBD in neonatal rats via increasing SOD level, decreasing MDA level, attenuating brain edema, decreasing apoptotic cells in cortex and alleviating atrophy of hypoxic-ischemic hemisphere.     

Effect of renal sympathetic denervation on cardiac hypertrophy and fibrosis

AIM:To investigate the effect of renal sympathetic denervation (RDN) on cardiac hypertrophy and fibrosis and to explore the underlying mechanisms. METHODS:Male SD rats were randomly divided into 4 groups: sham, sham plus RDN, aortic constriction (AC) and AC plus RDN group (n=15 for each group). After the intervention for 8 weeks, the haemodynamic data and cardiac function were measured by a physiological recorder. The histological structure of the heart was evaluated by HE and picro-sirius red staining. The plasma concentration of norepinephrine (NE), renin activity, angiotensin II (Ang II) concentration and cardiac Ang II level were determined by radioimmunoassay. RESULTS:Compared with AC group, RDN improved cardiac diastolic function ［left ventricular end-diastolic pressure: (8.03±1.66) mmHg vs(15.77±2.14) mmHg; -dp/dt: (7 793±587) mmHg/s vs(6 353±475) mmHg/s; both P<0.01］, inhibited cardiac hypertrophy ［left ventricular index: 3.340±0.121 vs4.244±0.102; cardiomyocyte area: (332.9±28.9) μm2 vs(401.6±33.2) μm2; both P<0.01］ and attenuated cardiac fibrosis (collagen volume fraction: 7.76%±0.85% vs12.48%±1.82%; P<0.01) in aortic constricted rats. However, RDN didn’t cause significant reduction of blood pressure in aortic constricted rats (P>0.05). RDN prevented the AC-induced increase in the plasma NE concentration, renin activity, Ang II concentration and cardiac Ang II level. CONCLUSION: RDN may directly prevent cardiac hypertrophy and fibrosis and improve cardiac function via regulating the sympathomimetic activity and renin-angiotensin system.     

Correlation of serum uric acid level with carotid plaques and arterial stiffness in patients with essential hypertension

AIM：To study the correlation of serum uric acid (UA) level with carotid plaques and arterial stiffness in the patients with essential hypertension (EH), and to explore the predictive value of serum UA for evaluating EH preclinically. METHODS：A total of 92 patients with EH and 30 healthy individuals were enrolled. The value of UA and other indicators were detected. B-mode ultrasound examination was performed to measure the common carotid artery intima-media thickness (IMT) and the sites of plaque in the internal carotid-artery, external carotid artery and carotid bifurcations. Carotid-femoral arterial pulse wave velocity (CFPWV) was assessed by Complior atherosclerosis measurement instrument. RESULTS：The serum level of UA in the patients with EH was higher than that in control group ［(361.51±83.81） μmol/L vs (317.03±62.22) μmol/L, P<0.05］. The mean value and abnormal rate of IMT between hypertension group and control group were significant difference ［(0.69±0.14) mm vs (0.60±0.12) mm, 42.39% vs 10.00%, P<0.05］. In 92 EH patients, 45 cases had carotid plaques. These 45 cases were divided into 3 groups according to the plaque severity, among which the serum UA level had statistically significant differences ［(285.25±78.41） μmol/L, （341.19±63.99） μmol/L and （401.33±88.49） μmol/L, P< 0.05］. Compared with rigid plaque group (n=34), the serum UA level in soft plaque group (n=11) was significantly higher ［(389.00±69.45) μmol/L vs （323.03±72.71） μmol/L, P<0.05］. A stepwise multiple linear regression analysis demonstrated that age (r=0.414), systolic blood pressure (r=0.224), pulse pressure (r=0.270) and uric acid (r=0.219) were predisposed factors for higher CFPWV (P<0.05). CONCLUSION：UA is one of the risk factors causing hypertension. Serum UA level may reflect the severity and stability of carotid plaques. The increased arterial stiffness is closely related to the increased serum UA level in EH.     

Scutellaria barbata flavonoids inhibits NFT aggregation and regulatory mechanism in rats induced by composited Aβ

AIM: To investigate the effects of Scutellaria barbata flavonoids (SBF) on neurofibrillary tangle (NFT) aggregation, tau protein phosphorylation and the regulated mechanism of glycogen synthase kinase (GSK) 3β and protein phosphatase (PP) 2A in the rats induced by amyloid β protein 25-35 (Aβ_25-35) in combination with AlCl₃ and recombinant human transforming growth factor (RHTGF)-β1(composited Aβ). METHODS: The male SD rats were used to establish the simulated Alzheimer disease (AD) model by intracerebroventricular injection of composited Aβ. The Morris water maze was applied for screening the successful model rats with learning and memory deficits. The successful model rats were daily and orally administrated with SBF at doses of 35, 70 and 140 mg/kg or positive control drug Ginkgo biloba leaves flavonoids (GLF) at 140 mg/kg for 37 d. The silver nitrate staining was used to determine the cortical NFT. The protein levels of total tau, phosphorylated protein of tau at Ser199 and Ser214 sites, GSK3β and PP2A in hippocampus and cortex were determined by Western blot. The mRNA expression of GSK3β and PP2A in the hippocampus and cortex was detected by RT-PCR. RESULTS: Compared with sham group, the cell number of positive NFT with silver nitrate staining in model rat cerebral cortex was significantly increased. The protein levels of phosphorylated tau protein at Ser199 and Ser214 sites, GSK3β in the hippocampus and cerebral cortex in the model rats dramatically elevated, and PP2A was marked decreased as compared with the sham group rats. Meanwhile, the mRNA expression of GSK-3β significantly increased but PP2A was decreased. However, these above abnormalities were differently attenuated by treating with SBF at different doses or GLF at 140 mg/kg for 37 d. CONCLUSION: SBF suppresses the NFT aggregation by inhibition of the regulatory functions of GSK-3β and PP2A, thus reducing the phosphorylation of tau protein.     

Effects of lipopolysaccharide and interleukin 1 receptor antagonist on proliferation and nitric oxide synthesis of mesangial cells

AIM: To investigate the effects of lipopolysaccharide (LPS) and interleukin-1 receptor antagonist (IL-1ra) on mesangial cells proliferation and nitric oxide synthesis. METHODS: Glomerular mesangial cells from SD rats were cultured. The first and second passages of cultured cells were used for the experiment. LPS and LPS plus IL-1ra were added in cell cultures, respectively. By using chemical method the nitrite in supernatants was measured, [³H]-TdR incorporation was determined to evaluate the GMC proliferation. Northern and slot hybridizations were performed to detect the expression of iNOS mRNA. RESULTS: There were expression of iNOS mRNA, more production of nitrite (0.64±0.25 vs 0.12±0.06 nmol/10⁴ cell) in supernatants and GMC proliferation (3735±1177.9 vs 1785±280.6) in LPS group compared to the control. While compared with LPS group, in LPS+IL-1ra GMC group, expression of iNOS mRNA decreased by 40%, nitrite increased (3.28±0.33nmol/10⁴ cell), proliferation of GMC decreased (818±77.27). CONCLUSION: LPS could activate the GMC to express iNOS mRNA and produce more nitrite. IL-1ra could partially inhibit the effects of LPS on the expression of iNOS mRNA in GMC, but not nitrite. There is no synchronous correlation between NO production and GMC proliferation.     

Role of bradykinin in the therapeutic effect of enalapril on left ventricular hypertrophy and cardiac function after myocardial infarction in rats

AIM:To investigate the influences of bradykinin(BK)on left ventricular hypertrophy and cardiac function in angiotensin-converting enzyme inhibitor(ACEI) therapy in rats after myocardial infarction.METHODS:The effects of enalapril (500 μg·kg^-1·d^-1), enalapril (500 μg·kg^-1·d^-1)with BKB₂ receptor antagonist (Hoe-140 500 μg·kg^-1·d^-1), losartan(3 mg·kg^-1·d^-1) on left ventricular end-diastolic pressure (LVEDP), maximum positive left ventricular pressure change (+dp/dt_max) and LVW/BW as well as V(m)n of noinfarcted area were examined after 4 weeks treatment in rats after myocardial infarction.RESULTS:The values of LVEDP, LVW/BW and V(m)n of three treatment groups were higher than that of untreated MI group (P＜0.05),but the +dp/dt_max of three treatment groups were not significantly different compared with the untreated MI group. In addition, no significant difference in MAP was observed among the three treatment groups, but the LVW/BW and V(m)n of enalapril+Hoe-140-treated group were higher than that of enalapril-treated group (P＜0.05) .CONCLUSION:Enalapril can prevent left ventricular hypertrophy and improve cardiac function independent of blood pressure after myocardial infarction, which is partly due to the inhibition of BK degradation.     

Effects of hydrogen peroxide on sodium current in acutely isolated rat hippocampal CA1 neurons

AIM and METHODS: The effects of hydrogen peroxide on Na⁺ currents were studied in freshly dissociated rat hippocampal CA1 neurons using the whole-cell patch-clamp techinique. RESULTS: ①H₂O₂ caused a dose-dependent and voltage-dependent increase in the voltage-activated Na⁺ currents. The amplitudes of Na⁺ currents were increased (48.0±4.2)% and (88. 2±5. 1)% (n=10) by H₂O₂ at 10 μmol/L and 100 μmol/L, respectively. ②H₂O₂ (10 μmol/L) did not affect the activation process, but changed the inactivation process significantly. Before and after application of 10 μmol/L of H₂O₂, the half-inactivation voltage was (-64.58±1.22)mV and (-53.55±0.94)mV (n=10, P<0.01), but the slope factor was not changed. CONCLUSION: As a product of oxidation metabolism, H₂O₂ is related to some diseases in the central nervous system.     

中甘21号

AIM: To observe the pathological role of 3-nitrotynosine (3-NT) on Escherichia coli LPS-induced vascular hyporeactivity in rats and the therapeutic effect of antioxidants. METHODS: Forty male SD rats weighting from 200 g to 250 g were randomly divided into four groups: the control group (n=10); LPS shock group (n=10); uric acid-treated group (n=10); melatonin-treated group (n=10). 6 h after LPS shock, phenylephrine (0.5-2.5 μg·kg-1) was applied intravenously to all groups and the percentage increase in MAP was detected, respectively. The concentration-response curve of aorta rings from all groups rats were obtained by cumulative addition of phenylephrine (PE), and PE Emax, EC50 were calculated. The concentrations of plasma malondialdehyde (MDA), nitrate/nitrite and 3-NT were assayed in all groups 6 h after LPS shock. RESULTS: The MAP level induced by PE significantly decreased to 54.60% in LPS shock rats compared with the control (P<0.05). However, PE induced MAP level increased 37.70% and 43.05% in uric acid and melatonin treated rats, respectively, compared with the LPS shock rats (P<0.05). The maximum response and EC50 to PE were significant reduced in LPS shock rats ［Emax, 35.30%±9.80%; EC50, (15.70±4.50)nmol/L］ compared with control group ［Emax, 100%; EC50, (4.71±2.04)nmol/L, P<0.05］; but the reactivity of aorta to PE was improved obviously in uric acid and melatonin treated groups (P<0.05). The plasma concentration of MDA, nitrate/nitrite and 3-NT were much lower in uric acid and melatonin groups than those in LPS shock group (P<0.05). CONCLUSIONS: 3-NT is an important pathological factor on vascular hyporeactivity in LPS shock. Antioxidants effectively improve α-adrenergic receptor-mediated vascular reactivity in LPS shock rats partially by removing lipid peroxidative production, reducing nitric oxide and 3-NT biosynthesis in LPS shock. These results suggest that antioxidants have potential beneficial therapeutic effect for septic shock patients.     

Effects of phosphodiesterase inhibitor-induced insulin resistance on glucose and lipid metabolism in rats

AIM:To investigate the effects of milrinone (a selective phosphdiesterase III inhibitor PDE₃) on insulin secretion, blood glucose, plasma free fatty acids (FFA) and dose-response relationship, and assess possible effects of milrinone on glucose metabolism and insulin sensitivity in conscious rats.METHODS:The catheterized nonstressed rats were administered by the varying doses of milrinone (1, 5, 25 μmol/kg) and were compared with controls. A hyperinsulinaemic- euglycaemic clamp was established in awake rats, and milrinone(25 μmol/kg) and 25% dimethyl sulfoxide (DMSO, as a control) were given at 120 min during hyperinsulinaemic- euglycaemic clamp. Glucose turnover was decided by gas chromatograph mass spectrometer (GC-MS).RESULTS:After dosing, plasma FFA levels in 3 milrinone groups significantly increased compared with the controls and before dosing. The percentages of elevation of FFA by the different milrinone doses were very similar, 50%, 52%, 55% for 1, 5, 25 μmol/kg respectively at 2 min after dosing. Plasma insulin levels were significantly elevated in the 5 and 25 μmol/kg groups, and the effect of milrinone on glucose concentration was detectable only 25 μmol/kg group. During hyperinsulinaemic clamp, there were significant increase in plasma FFA (from 173.1±15.2 to 633.8±87.3 μEq/L) and hepatic glucose production (HGP), and a significant decrease in glucose infusion rates (GIR) (to about 21%).CONCLUSION:These data suggest that milrinone impaires the abilities of insulin to suppress lipolysis and HGP, and insulin-mediated glucose utilization in peripheral tissue. Therefore, milrinone administration may induce an acute insulin resistancein vivo.     

Cardioprotective effect of sevoflurane preconditioning on ROS production in rat heart with ischemia-reperfusion

AIM: To investigate the effects of sevoflurane preconditioning on the production of reactive oxygen species (ROS) and nitric oxide (NO), the activity of superoxide dismutase(SOD), glutathione peroxide(GPx) and catalase(CAT) in myocardial ischemia-reperfusion injury(IRI). METHODS: Sixty rats were randomly allocated to 8 groups. Following 2% sevoflurane preconditioning for 30 min, the left anterior descending artery was ligated for 30 min and then reperfused for 120 min in vivo. The infarction size of the hearts was measured with the staining of 2,3,5-triphenyltetrazoliumchloride. The myocardial apoptotic index was measured by the method of TUNEL. The ROS fluorescent probe dihydroethidium was used for the measurement of ROS. The myocardium was homogenized for the measurement of NO, SOD, GPx and CAT. To evaluate the effects of ROS and NO on the cardioprotection of sevoflurane preconditioning, ROS scavenger N-(2-mercaptopropionyl) glycine (2-MPG) or NOS inhibitor N^ω-nitro-L-arginine methyl ester (L-NAME) were employed to block their actions. RESULTS: Compared with control group, the production of ROS was induced by sevoflurane preconditioning before ischemia-reperfusion injury (12.0±0.8 vs 2.6±0.5, P<0.05) and decreased after ischemia-reperfusion injury (16.2 ±0.9 vs 24.9±1.3, P<0.05). 2-MPG decreased the elevation of ROS caused by sevoflurane preconditioning before ischemia-reperfusion injury (5.1±0.7 vs 12.0±0.8, P<0.05). No difference of ROS production between treating with 2-MPG+Sevo+IRI and with IRI (24.9±1.4 vs 24.9±1.3, P>0.05) was observed. Compared with control group, sevoflurane preconditioning also induced the generation of NO (34.5±3.2 vs 15.9±1.4, P<0.05) and the activity of SOD(1.5±0.5 vs 0.6±0.2, P<0.05), GPx(22.8±2.5 vs 12.7±2.2, P<0.05) and CAT(15.5±1.8 vs 11.2±1.4, P<0.05). 2-MPG blocked the increase in NO production and inhibited the activity of SOD,GPx,CAT. L-NAME also attenuated the activity of SOD,GPx,CAT. CONCLUSION: Sevoflurane preconditioning protects the rat heart against ischemia-reperfusion injury by reducing the infarction size and apoptosis. Production of ROS at sub-injury dose induced by sevoflurane preconditioning stimulates the myocardium to create SOD,GPx,CAT and NO, thus inhibiting the further formation of ROS and protecting the heart under the condition of ischemia-reperfusion.     

Effect of transmyocardial laser revascularization on myocardial lactatic metabolism and mitochondria of myocardial cells

AIM: We studied the therapeutic effect and mechanism of transmyocardial laser revascularization (TMLR) for the acute myocardial ischemia (AMI). METHODS: 18 dogs were divided randomly and evenly into the control group, the AMI group and the TMLR group. A continuous wave Nd: YAG laser was used for TMLR. Concentration of lactate in artery and coronary sinus (A.Lat and CS.Lat), myocardial metabolic rate of lactate acid (MLR) and myocardial lactate extraction (MLE) were measured before the left anterior descending coronary artery (LAD) ligation and 60 min after the LAD ligation. Myocardial biopsy was made 4 h after the LAD ligation to quantitatively observe the shape and number of mitochondria in myocardial cells by a electric microscope. RESULTS: 60 min after the LAD ligation, CS.Lat were (7.63±4.27) mmol/L in the AMI and (5.78±3.98) mmol/L in the TMLR, respectively (P<0.05); MLR were (0.03±0.01) mmol·100 g^-1 myocardium·min^-1 in the AMI and (0.06±0.02) mmol·100 g^-1 myocardium·min^-1 in the TMLR, respectively (P<0.05); MLE were (12.04±3.04) in the AMI and (21.84±8.49)% in the TMLR, respectively (P<0.05). The volume density of mitochondria were (27.51±7.93)% in the AMI and (31.26±3.85)% in the TMLR, respectively (P>0.05). The area density of mitochondria were (1.25±0.18) μm^-1 in the AMI and (1.64±0.28) μm^-1 in the TMLR, respectively (P<0.01). The number density of mitochondria were (0.10±0.03) μm^-3 in the AMI and (0.18±0.05) μm^-3 in the TMLR, respectively (P<0.01). The average volume of mitochondria were (5.27±2.85) μm³ in the AMI and (2.80±0.54) μm³ in the TMLR, respectively (P<0.05). The average diameter of mitochondria were (2.06±0.36) μm in the AMI and (1.78±0.12)μm in the TMLR, respectively (P＜0.05). CONCLUSION: The study suggests that TMLR may effectively improve myocardial lactatic metabolism and protect the myocardial cells from ischemic injury in dogs with the AMI.     

Effect of selenium compounds on ROS and NO production and NOS activity in human umbilical cord mesenchymal stem cells

AIM: To investigate the effects of selenium (Se) compounds on the generation of nitric oxide (NO) and reactive oxygen species (ROS), and the activity of nitric oxide synthase (NOS) in umbilical cord mesenchymal stem cells (MSCs). METHODS: MSCs were cultured in the medium of DMEM/F12 containing 10% FBS and exposed to the compounds of selenium , selenocysteine (Se-Cys) or nano-selenium (Nano-Se) at concentrations of 0.1 μmol/L to 0.5 μmol/L. The concentration of NO and the activity of NOS in treated MSCs were detected by the method of nitrate reductase assay. The fluorescent intensity of ROS was determined by DCFH-DA probe. RESULTS: The production of NO was (18.13±6.80) μmol/L in the control MSCs,(20.93±5.68) μmol/L in the MSCs treated with Se(Ⅳ) at concentration of 0.1 μmol/L and (16.73±5.03) μmol/L in the MSCs treated with Se(Ⅳ) at concentration of 0.5 μmol/L for 24 h. The production of NO was (17.20±9.11) μmol/L (P<0.05) in the MSCs treated with Se(IV) at concentration of 0.1 μmol/L and (9.98±4.35) μmol/L (P<0.01) in the MSCs treated with Se(IV) at concentration of 0.5 μmol/L for 48 h, which was significantly lower than that in the control MSCs . No inhibitory effect of Nano-Se and Se-Cys on the production of NO in MSCs was observed. Compared with the control MSCs, Se(Ⅳ) at concentrations of 0.1 μmol/L and 0.5 μmol/L significantly inhibited the generation of ROS and the activity of NOS in MSCs at 24 h and 48 h. CONCLUSION: Se(Ⅳ) inhibits NO/ROS production and NOS activity in a dose-dependent manner in MSCs.     

Dynamic changes of the concentration of nitric oxide in ischemic myocardium and its mechanism

AIM: The study was undertaken to explore the dynamic changes of the concentration of nitric oxide(NO) in ischemic myocardium and its mechanism.METHODS: In vivo myocardial ischemia of mice and in vitro perfused isolated heart of rat were used in the experiment. The effects of severity and time of ischemia on NO production, NOS activity and mRNA were examined, respectively. RESULTS: There was a considerable difference (P<0.01) in the concentration of NO between ischemia group [(9.12±1.40) μmol/L] and control group [(20.16±1.67) μmol/L] after Pit(30 U/kg) administration, and the concentration of NO of ischemic group significantly decreased [(9.17±1.33) μmol/L] compared with control group [(19.90±1.95) μmol/L] after 30 minutes of ischemia. Also, the concentration of NO after Pit(20 U/L) administration in K-H and 15 min of ischemia was (15.41±2.00) μmol/L and (15.09±2.00) μmol/L respectively in vitro, significantly lower than control group [(23.83±2.33) μmol/L and (23.63±2.52) μmol/L]. In addition, compared with control group, the number of NOS positive cells, NOS activity as well as mRNA expression in atrial muscle and ventricular muscle of ischemic group were markedly reduced, respectively. CONCLUSION: Myocardial ischemia could reduced the NO level in myocardium, down-regulation of NOS mRNA could be the possible mechanism.     

Expression of peroxisome proliferator-activated receptor α in rat fatty liver

AIM:To investigate the role of expression of peroxisome proliferator-activated receptor α(PPAR α) in pathogenesis of rat fatty liver.METHODS:The rats were treated with a low dose of carbon terachloride (CCl₄) and fed a high fat diet to produce fatty liver. We determined the concentrations of triglyceride (TG), total cholesterol (TC), free fatty acid (FFA) in liver and the alanine aminotransferase (ALT) activity, tumor necrosis factor-α (TNF-α), FFA in serum and the degree of hepatocytic steatosis. Total RNA of liver was extracted, and the expression of PPAR α were analyzed by semi-quantitative RT-PCR method.RESULTS:In model group, the hepatocytic PPAR α mRNA expression decreased to 0.41±0.28, compared to 1.41±0.29 in the control group (P＜0.01). The contents of TG, TC, FFA in model rat liver were (1.88±0.20) mmol·L^-1, (11.03±1.12) mmol·L^-1 and (1 260.38±151.27) μmol·L^-1, respectively, compared to (0.53±0.10) mmol·L^-1, (1.25±0.25) mmol·L^-1 and (334.30±27.09) μmol·L^-1 in the control group (P＜0.01). The activity of ALT, concentrations of TNF-α and FFA in serum were also increased remarkably in model group.CONCLUSION:Oxidation of fatty acid and utilization of lipids in liver are affected by reducing the expression of PPAR α, which result lipid accumulation in liver.