Mechanisms of hepatocytic mitochondria damage following septic shock

AIM: To study mechanism of hepatocytic mitochondria damage following septic shock. METHODS: 30 SD rats were randomly divided into three groups: sham operation group, 12 h cecal ligation and puncture (CLP) group and 16 h CLP group. The model of septic shock was made by cecal ligation and puncture. The liver mitochondria respiratory control rate (RCR), phosphate/oxygen (P/O) and ATPase activities were assayed. RESULTS: In 12 h CLP group mean artery pressure (MAP) [(9.54±1.26)kPa] was significantly lower than sham operation group [(14.58±1.32)kPa,P<0.05]. However, mortality was obviously higher than sham operation group (P<0.05), the liver mitochondria respiratory control rate (1.27±0.25), phosphate/oxygen (1.67±0.34) and Na⁺-K⁺-ATPase (40.80±3.45), Ca²⁺-ATPase (58.00±2.43), Mg²⁺-ATPase (78.30±4.16), Ca²⁺-Mg²⁺-ATPase(2.70±2.25) activities decreased strikingly. The difference between 12 h CLP group and sham operation group was significant (P<0.05), 16 h CLP groups was more lower than 12 h CLP group. As RCR, P/O and ATPase activities were significantly reduced, mortality significantly increased. Futhermore, obvious positive correlation was showed between them (r=0.892,P<0.01;r=0.834,P<0.01). CONCLUSION: Liver mitochondria function of ingestion-oxygen and phosphorus-acidification are decreased and membrane fluxion is weaken. Energy metabolism is blocked and Ca²⁺-Mg²⁺ shows imbalanced. All of them cause hepatocytic mitochondria injury following septic shock.     

Taurine reduced oxygen free radical production induced by homocysteine in electron transport chain and homocysteine inhibites taurine transporter in mitochondria membrane

AIM: To observe effects of homocysteine and antagonized effects of taurine on electronic leakage and free radical production in myocardial mitochondria. METHODS: Myocardial mitochondria of rat heart was isolated, and was broken by supersonic wave to prepare submitochondria. Recombinant of succinic acid cytochrome c reductase was prepared with mitochondria of porcine heart. They were co-incubated with homocysteine and/or taurine with various concentration. The H₂O₂ and O₂^- were determined by chemiluminescence methods. The taurine transporter of heart mitochondria and its propert, and effects of homocysteine on its function were studied with glass filter. RESULTS: Homocysteine stimulated oxygen free radical production in heart mitochondria, submitochondria, and succinic acid cytochrome c in a concentration-dependent manner. Although taurine itself did not affect oxygen free radical production, taurine did inhibit oxygen free radical production in mitochondria, submitochondria and succinic acid cytochrome c in a concentration-dependent manner. Taurine transporters of Na⁺-dependent were existed in mitochondria membrane. Homocysteine inhibited taurine transtport in mitochondria in a concentration-dependent manner. CONCLUSIONS: Taurine inhibited electronic leakage and oxygen free radical production induced by homocysteine in electron transport chain. There were taurine transporters in mitochondria membrane, and transport functions of taurine transporter were inhibited by homocysteine.     

Effect of L-arginine on function and structure of mitochondria in ischemia-reperfusion myocardial cells in rabbits

AIM: To study the effect of L-arginine (L-Arg) on function and structure of mitochondria in ischemia-reperfusion (MRI) myocardial cells. METHODS: Thirty rabbits were randomly divided into three groups (n=10 in each), control group, MIR group and MIR+L-Arg group. The mitochondrial respiratory function, Ca²⁺ concentration ([Ca²⁺]m), malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were determined. Meanwhile, the contents of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), total adenylic acid number (TAN) and energy charge (EC) in the myocardial tissue were respectively measured. Moreover, the ultrastructure changes in myocardial mitochondria were observed during MIR. RESULTS: The mitochondrial respiratory control rate (RCR), velocity 3 (V₃), SOD, surface density (Sv) and specific surface (δ) in MIR+L-Arg group were higher than those in MIR group, velocity 4 (V₄), [Ca²⁺]m, MDA, volume density (Vv), horizental diameter (Hd) were lower than those in MIR group. ATP, ADP, TAN and EC levels of myocardial tissue were higher than those in MIR group. There was no significant difference between MIR+L-Arg and control group in V₃, V₄, SOD, MDA, Vv, Sv, δ, Nv, Vd, AMP and TNA. CONCLUSION: It is suggested that L-Arg improves the function and structure of mitochondria in myocardial cells in the reperfusion injury after myocardial ischemia by decreasing oxygen free radical level and Ca²⁺ overload in the mitochondria.     

Adaptation characteristics of mitochondria in plateau pikas at different altitudes

AIM: To investigate the adaptive characteristics of mitochondria in plateau pikas at different altitudes. METHODS: According to the altitudes of the capture area, plateau pikas were divided into 4 300 m group (Mado Star Sea, n=6) and 2 900 m group (Laoji Mountain South, n=6). The red blood cells and hemoglobin of the animals in 2 groups were measured. The levels of mitochondrial oxidative phosphorylation (OXPHOS) and fatty acid oxidation (FAO) in the liver and skeletal muscle, and mitochondrial H₂O₂ production level in the skeletal muscle were determined by high-resolution mitochondrial respirometer. RESULTS: The hemoglobin of the plateau pika in 4 300 m group was significantly lower than those in 2 900 m group. The liver state 4 respiration rate of mitochondrial respiratory chain complex I (CI-LEAK), mitochondrial respiratory chain complex I state 3 respiration rate (CI-OXPHOS) and respiratory chain complex I+Ⅱ state 3 respiration rate(CI+Ⅱ-OXPHOS), electron transfer capacity of respiratory chain complex I+Ⅱ (CI+Ⅱ-ETS), the electron transport capacity of the respiratory chain complex Ⅱ (CⅡ-ETS) in 2 900 m group were increased, and the coupling efficiency was decreased compared with 4 300 m group (P<0.05). The skeletal muscle CI-LEAK,CI+Ⅱ-OXPHOS and CI+Ⅱ-ETS were higher than those in 4 300 m group. Mitochondrial state 4 respiration rate with palmitic acid carnitine and malate as substrates (FAO-LEAK) of liver and skeletal muscle in 2 900 m group were increased compared with 4 300 m group. The skeletal muscle with palmitic acid carnitine as a substrate for fatty acid metabolism state 3 respiratory rate (FAO-OXPHOS) was increased in 2 900 m group compared with 4 300 m group. The H₂O₂/O₂ flow ratio (ΔH₂O₂) in 2 900 m group was lower in state 4 respiration rate of mitochondrial respiratory chain complex I (LEAK), state 3 of mitochondrial respiratory chain complex I (OXPHOS), state 3 of mitochondrial respiratory chain complex I+Ⅱ (OXPHOS*) and electron transfer capacity of respiratory chain complex I+Ⅱ (ETS) than 4 300 m group. CONCLUSION: Plateau pikas with different altitudes have different mitochondrial adaptation characteristics.     

Effects of Shenmai injection on acute myocardial ischemia/reperfusion injury in rats

AIM: To observe the effect of Shenmai injection on the acute myocardial ischemia/ reperfusion injury in rats. METHODS: The left-anterior coronary artery was ligated for 10 minutes and then loosed for 15 minutes to establish the animal model of acute myocardial ischemia/reperfusion injury. During the process, electrocardiogram was traced continuously to observe the arrhythmia caused by reperfusion. The levels of SOD, MDA, Na⁺, K⁺-ATPase and Ca²⁺ -ATPase in ventricular myocardium were measured. The mitochondria was observed through electron microscope. RESULTS: Shenmai injection decreased the incidence of arrhythmia caused by reperfusion and shortened its duration. Shenmai injection improved the activity of SOD, Na⁺, K⁺-ATPase and Ca²⁺ -ATPase, decreased the content of MDA in myocardium and relieved the injury of mitochondria. CONCLUSION: Shenmai injection had a protective effect on acute myocardial ischemia/reperfusion injury in rats. The mechanism may be related to relieving the injury caused by oxygen free radical and calcium overload.     

Protective effects of extract of Ginkgo biloba on diaphragm of diabetic rats

AIM: To investigate the effects of extract of Ginkgo biloba (EGb) on diaphragm from diabetic rats. METHODS: Sprague-Dauley rats were divided into three groups: normal control, diabetic group and EGb treatment group. The morphologic changes of diaphragm tissues were studied by light and electron microscopy, the activities of succinate dehydrogenase (SDH), superoxide dismutase (SOD), nitric oxide synthase (NOS) and contents of malondialdehyde (MDA), nitric oxide (NO₂^-/NO₃-) in the diaphragm mitochondria were assayed by spectophotometer, respectively. RESULTS: The activities of SOD, SDH decreased in diabetic diaphragm mitochondria, but the activitiy of NOS, the contents of NO₂^-/NO₃^-, MDA increased compared with control group. The activities of SOD, SDH were increased as well as NOS were decreased and the contents of NO₂^-/NO₃^-, MDA decreased in EGb treatment group compared with the diabetic group. CONCLUSION: EGb may protects the diaphragm mitochondria of diabetic rats by enhancing the function of respiratory chain, anti-oxidation and decreasing NO level.     

Detection of serum MDA,NO and INOS in patients with SARS andits clinical significance

AIM: To observe free radicals (MDA, NO) and iNOS of patients with severe acute respiratory syndrome (SARS) and to explore its significance. METHODS: MDA, NO₂^-/NO₃^- and iNOS were determined in SARS patients during the early, recovery and follow-up stage, front doctors and nurses (contact group) and health people (health control). RESULTS: The level of MDA during first stage was higher than that of recovery stage and the MDA level of recovery stage was higher than that of follow-up stage, contact group, and health control group (P<0.01). The content of NO₂^-/NO₃^- during early stage was higher than that of other groups, and the NO₂^-/NO₃^- contents of recovery stage, follow-up stage were higher than that of contact group and health control group (P<0.01), respectively. The mean of iNOS during early stage was highest than that of other stages (P<0.01) and the mean of recovery stage was higher than that of contact group (P<0.05), there were no difference in iNOS activity among any other groups (P>0.05). CONCLUSION: The pathological injury in pathogenesis of SARS is related to free radicals.     

Involvement of mtNOS in the Ca2+-induced damages of myocardial mitochondria during the early stage after severe burns

AIM:To study the role of mitochondrial nitric oxide synthase (mtNOS) in the damages of myocardial mitochondria during the early stage after severe burns.METHODS:An experimental model of 30% TBSA full-thickness skin scalding was reproduced in rats. Myocardial mitochondria were isolated from control and burned rats at 1, 3, 6, 12 and 24 h postburn. The mitochondrial respiratory function, content of mitochondrial calcium( [Ca²⁺]_m) and activities of mtNOS and cytochrome c oxidase were determined. RESULTS: (1) Myocardial mitochondrial respiratory control rate(RCR) at 1 h was evidently higher than that of control, but at 3, 6, 12 and 24 h postburn, it was significantly lower than that of the control. The changes in ST₃ is parallel to those of RCR, and ST₄ was evidently increased only at 3 h postburn. (2) [Ca²⁺]_m was higher at all time points postburn and the activity of mtNOS was higher significantly only at 3, 6, 12 and 24 h than that of the control. The activity of cytochrome c oxidase at the 3, 6, 12 and 24 h was low comparing to the control. (3) After severe burns, RCR was negatively correlated with mtNOS activity(r=0.9347, P＜0.05) and mtNOS activity was positive correlated with [Ca²⁺]_m (r=0.8945, P＜0.05). CONCLUSION:The elevation of [Ca²⁺]_m significantly activates mtNOS, which might play an important role in the damages of myocardial mitochondria during the early stage after burn injury.     

Mechanisms underlying the protective effect of renal ischemic preconditioning on ischemia-reperfusion myocardium of rabbits

AIM: To investigate the mechanisms underlying the protective effect of kidney ischemic preconditioning on rabbit myocardium in case of ischemia-reperfusion and the possible role of oxygen free radicals in the process. METHODS: Animals were divided into four groups: ischemia/reperfusion(I/R), classical ischemic preconditioning(CIPC), kidney ischemic preconditioning (KIPC) and superoxide dismutase in combination with kidney ischemic preconditioning(SOD+KIPC). The endo genous myocardial pretective material, nitric oxide(NO) and 5'-nucleotidase(5'-NT) were checked in four groups. RESULTS: As compared with I/R group, both CIPC and KIPC could ameliorate left ventricular function, reduce plasma PLA₂ activity and arrhythogenic rate also, the myocardial 5'-NT and NO production were significantly higher than that of the rabbit of I/R group. However, the protective effect on rabbit myocardium was significantly weakened by the SOD administration before the ischemic preconditioning. CONCLUSION: Protective effect of KIPC on myocardium may be due to increase in endo genous myocardial protective materials, oxygen free radicals may play an important role in the endo genous myocardial protective material release.     

Protective effect of Ligustrazini on gut barrier function

AIM:To study the protective effect of Ligustrazini(LGT) on gut barrier function after hemorrhagic shock-reperfusion. METHODS: Thirty white rabbits were divided randomly into 3 groups: control group (A),shock group (B) and LGT group (C). Malondialdehyde(MDA), tumor necrosis factor-α(TNF_α), interleukin-1β(IL-1β) and nitric oxide products(NO₂^-/NO₃^-) contents were measured in intestinal mucosa at 3 hours following reperfusion,culture of bacteria in blood from rabbits of 3 groups was carried out,the intestinal mucosa was examined under optical and electron microscope. RESULTS: MDA, TNF_α, IL-1β and NO₂^-/NO₃^- contents of intestinal mucosa remained unchanged in group C,but increased significantly in group B, compared with group A. Incidence of bacterial translocation in group B was markedly higher than that in group A at 30 min following reperfusion,there was not any difference between group A and group C. Under light and electronic microscope,in comparison with A and C groups,intestinal mucosa damage in B group became more severe. CONCLUSION: LGT can protect gut barrier from intestinal ischemia-reperfusion injury induced by hemorrhagic shock through reducing oxygen free radicals,raising nitric oxide and preventing inflammation.     

ATPase activities and Ca2+/calmodulin alterations in hippocampi of rats with PTSD-like behaviors

AIM: To explore the pathophysiological bases in the pathogenesis of the lasting emotional behavioral disorders following posttraumatic stress disorder(PTSD). METHODS: 240 male Wistar rats were divided randomly into 3 groups. Group SE(n =96) for rats with PTSD-like behavior by constant pulsating current of 100 μA with intratrain frequencies of 16 Hz, pulsating duration of 1 ms, train duration of 10 s and interstimulus interval of 7 min for 5 days with 8 times per day. Group CE(n =96) for control with electrode implanted in hippocampus without stimulation, and Group NC(n =48) for normal control. The activities of Na⁺-K⁺-ATPase and Ca²⁺ -ATPase, levels of intracellular calcium and free calmodulin(CaM), and the total CaM expression were detected in hippocampi of experimental rats. RESULTS: The activities of Na⁺-K⁺-ATPase and Ca²⁺ -ATPase in mitochondria of hippocampal cells in Group SE rats were significantly decreased at 48 h and 72 h after the last stimulation, respectively. The intracellular free calcium levels were increased, and the mean channel fluorescence of intracellular free CaM decreased remarkably at 72 h poststimulation, while the expression of total CaM was significantly elevated at 48 h after the last stimulation in hippocampi of Group SE rats. CONCLUSION: The lasting increased levels of intracellular free calcium and expression of Ca²⁺ -CaM in hippocampus, as well as the dysfunction of Na⁺-K⁺ pump and Ca²⁺ -ATPase in mitochondria may play important roles in the long-term neuropsychological sequelae in PTSD.     

Effects of Liqustrazin on respiratory enzymes in the myocardial mitochondria of the ischemia-reperfusion rats

AIM: To study the effects of Liquestrazin on succinic dehydrogenase (SDH) and cytochrome oxidase (CCO) in the myocardial mitochondria of the ischemia-reperfusion rats and its mechanism. METHODS:Model of myocardial ischemia-reperfusion injury was produced by coronary artery ligation . The rats were devided into sham operation control (SC), ischemia-reperfusion (IR) and ischemia-reperfusion protected with Liqustrazin (IR+L) group . Activity of SDH,CCO,SOD and GSH·PX and contents of malondialdehyde (MDA),Cyt aa₃,Cyt c and phospholipid(PL) were observed respectively . RESULTS: As compared with ischemia-reperfusion group (IR), IR+L group showed significantly increased activity of SDH, CCO,SOD and GSH·PX (P＜0.01) , MDA content decreased significantly , the contents of Cyt aa₃ , Cyt c and PL increased respectively . CONCLUSION : Liqustrazin has notable antagonistic effects on decrease in SDH and CCO activities in the myocardial mitochondria of the ischemia-reperfusion rats , which is due to its oxygen free radicals scavenging action and its anti-lipid peroxidation reaction.     

Effects of benazepril on cardiac function,free oxygen radicals,sarcoplasmic reticulum Ca2+-ATPase following cardiac ischemia-reperfusion in spontaneously hypertensive rats

AIM: To investigate the effects of angiotensin converting enzyme inhibitor (ACEI), benazepril (B), on cardiac function , free oxygen radicals, sarcoplasmic reticulum(SR) Ca²⁺-ATPase following ischemia-reperfusion in sportaneously hypertensive rats (SHRs). METHODS: Thirty 10-week-old female SHRs were randomly assigned into two groups: group SHR was control; The animal in group SHR+B was given with 10 mg/kg of benazepril per day. Another 15 Wistar rats with the same age and sex were normal control (group Wistar). After 12 weeks of pretreatment, all rats in each group were subjected to 30 min of left anterior descending coronary artery occlusion and 30 min of reperfusion. Hemodynamic parameters, left heart-to-body weight ratio (LVW/BW), myocardial malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity, and SR Ca²⁺-ATPase activity were measured. RESULTS: Compared to group Wistar, the rats in group SHR had higher blood pressure, LVW/BW and myocardial MDA concentration, more serious left cardiac function injury and lower myocardial SOD activity and SR Ca²⁺-ATPase activity; group SHR+B had lower myocardial MDA concentration, higher myocardial SOD activity, but no difference in blood pressure, LVW/BW, the degree of left cardiac function injury and myocardial SR Ca²⁺-ATPase activity. CONCLUSION: Benazepril can attenuate ischemia-reperfusion-induced cardiac function injury by regression of left ventricular hypertrophy (LVH), improving SR Ca²⁺-ATPase activity and decreasing oxygen free radicals injury in SHRs.     

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.     

Protective role of heat-shock protein 70 in gastric mucosal lesion induced by endotoxin in cirrhotic rats with portal hypertensive gastropathy

AIM: To investigate the protective role of heat-shock protein 70 (HSP70) in the pathogenesis of gastric mucosal damage in cirrhotic rats with portal hypertensive gastropathy (PHG).METHODS: The rat model of liver cirrhosis with PHG was established by injection with tetrachloride.The animals were divided into normal control group, PHG group, PHG+heat treatment group, PHG+BPI21 group and PHG+endotoxin groups.The endotoxin used in the experiment was at the dose of 3 mg/kg and endotoxin antagonist BPI21 was at the dose of 2 mg/kg.HSP70 was induced by pre-treating the animals with mild whole-body heating.The levels of HSP70 and tumor necrosis factor alpha (TNF-α) in the gastric mucosa were measured by ELISA.Furthermore, the pathological changes of the gastric mucosa were observed under microscope with HE staining.RESULTS: Compared with the normal control rats, the rats in PHG group showed obvious gastric pathological lesion, decrease in HSP70 production and increase in TNF-α level in the gastric mucosa, and increased endotoxin concentration in the plasma.Compared with PHG+endotoxin group, the gastric mucosal lesion in PHG+BPI21 group was significantly attenuated, accompanied by the increase in HSP70 production and decrease in TNF-α level in the gastric mucosa.Heat treatment increased HSP70 production and decreased TNF-α concentration in the PHG rats, thus attenuating the gastric mucosal damage.CONCLUSION: HSP70 alleviates the gastric mucosal lesion induced by endotoxin in cirrhotic rats with PHG and decreases the concentration of TNF-α in gastric mucosa, indicating a protective role of HSP70 in the pathogenesis of gastric mucosal damage in PHG.     

Effect of forsythiaside A on immune function in rats with ulcerative colitis

AIM To investigate the effect of forsythiaside A (FA) on immune function in rats with ulcerative colitis and its related mechanism. METHODS Healthy SD rats were randomly divided into 5 groups: control group (no treatment, normal feeding), model group (establishment of rat ulcerative colitis model), and low, medium and high doses of FA groups (treatment of the model rats with FA at 5 mg/kg, 20 mg/kg and 80 mg/kg, respectively). The malondialdehyde (MDA) content and superoxide dismutase (SOD) activity in rat colon tissues were measured by colorimetry, and the serum levels of tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2) and IL-4 were detected by ELISA. The spleen index and thymus index, the percentages of CD3⁺, CD4⁺ and CD8⁺ T-lymphocytes in peripheral blood mononuclear cells （PBMC）, the serum IgA and IgG levels, and the serum complement C3 and C4 levels were also determined. RESULTS The colon tissues of the rats in model group showed obvious inflammation and ulceration, indicating that the animal model was successfully established. Compared with model group, the colonic inflammation and ulceration were significantly attenuated in FA groups, among which the high dose had the best effect. Compared with control group, the spleen index and thymus index of the rars in model group were decreased (P<0.05), MDA content in colon tissues was increased (P<0.05), and SOD activity in colon tissues was decreased (P<0.05). The levels of CD3⁺, CD4⁺, CD8⁺ and CD4⁺/CD8⁺ T-lymphocytes in PBMC, and the serum levels of C3, C4 and IL-4 were decreased (P<0.05), while the serum levels of IgA, IgG, TNF-α, and IL-2 were increased in model group as compared with control group. Furthermore, the spleen index and thymus index of the rats in FA groups were increased (P<0.05), the MDA content in the colon tissues was decreased (P<0.05), and the SOD activity in the colon tissues was increased (P<0.05). The levels of CD3⁺, CD4⁺, CD8⁺ and CD4⁺/CD8⁺ T-lymphocytes in PBMC, and the serum levels of C3, C4 and IL-4 were increased (P<0.05), while serum IgA, IgG, TNF-α and IL-2 levels were decreased in FA groups as compared with model group (P<0.05). CONCLUSION Forsythiaside A effectively attenuates the colonic lesions in rats with ulcerative colitis, and its mechanism may be related to reinforcement of oxygen free radical scavenging power, alleviation of inflammatory response, and enhancement of immune function.     

Characteristics of energy metabolism in brain mitochondria of rats exposed to hypoxia

AIM:To explore the characteristics of energy metabolism in brain mitochondria of rats exposed to acute and chronic hypoxia. METHODS: Animal grouping: Wistar rats were randomized into acute hypoxic group (AH), chronic hypoxic group (CH) and the control. Respiratory function, F₀F₁-ATPase activity, mitochondrial ATP, ADP and AMP contents and ATP production rate were measured respectively. RESULTS: In AH, brain mitochondrial respiratory state IV (ST₄) was increased, while respiratory control rate (RCR), mitochondrial ATP content, ATP production rate and F₀F₁-ATPase activity were decreased respectively. In CH, ST₄, RCR, mitochondrial ATP content and F₀F₁-ATPase activity were reversed partially.CONCLUSION: Acute hypoxia may impair brain mitochondria energy metabolism by way of depressing mitochondrial oxidative phosphorylation and ATP production and these parameters gain partial reablement during chronic hypoxia.     

The preventive effect of Panax notoginseng saponins (PNS) on chronic hypoxic pulmonary hypertension in rats

AIM: To investigate the preventive effect of PNS on chronic hypoxic pulmonary hypertension in rats. METHODS: Pulmonary arterial pressure observation, hematocrit (Hct)measurement, biochemical analysis and transmission electron microscopy were conducted to investigate the role of PNS. RESULTS: (1)Mean pulmonary arterial pressure (mPAP), right ventricular mean pressure (RVMP) and Hct were significantly higher in hypoxia group (H group) than that of control group (C group) and were much lower in hypoxia with PNS group (HT group) than that in H group; (2) Nitric oxide (NO₂^-/NO₃^-) concentration and nitric oxide synthase (NOS) activity in the plasma and the lung tissue, total superoxide dismutase (T-SOD) and copper/zinc-containing enzyme (Cu/ZnSOD) activities in the plasma were all significantly lower in H group than that in C group and were much higher in HT group than that in H group, but NO₂^-/NO₃^- concentration and NOS activity were still markedly decreased in comparison with C group; (3) Injury of endothelial cells in pulmonary arteriole was improved obviously in HT group Compared with H group. CONCLUSIONS: These results suggest that PNSreduces the increase in mPAP, probably through adjusting NOlevel, anti-damaging effectof free radicals, inhibiting the injury of endothelial cells and decreasing Hct.     

Salidroside increases release of intracellular free Ca2+ from sarcoplasmic reticulum in cultured rat cardiomyocytes

AIM: To observe the effects of salidroside on intracellular free Ca²⁺ concentration in cultured rat cardiomyocytes. METHODS: Primarily cultured cardiomyocytes of neonatal rats were divided into control group, different concentrations of salidroside groups and verapamil pretreatment+different concentrations of salidroside groups. The fluorescent intensity of intercellular free calcium concentration ([Ca²⁺]_i) in cultured cardiomyocytes of newborn rats loaded with fluo-3/AM(5 μmol/L) was measured by laser scanning confocal microscopy. RESULTS: Salidroside at concentrations of 15 mg/L, 30 mg/L and 60 mg/L elevated [Ca²⁺]_i in cultured rat cardiomyocytes with the peak values of 574.08±4.65, 591.86±3.64 and 618.66±4.27, respectively (all P<0.01), indicating that the effect of salidroside on the level of [Ca²⁺]_i was dose-dependent. In the presence of verapamil in D-Hanks solution, salidroside also elevated the fluorescent intensity of [Ca²⁺]_i in cardiomyocytes from 357.74±3.13, 387.17±2.37 and 391.43±1.34 to 480.86±3.98, 496.70±3.08 and 522.18±3.19, respectively (all P<0.01). CONCLUSION: Salidroside increases the release of [Ca²⁺]_i from sarcoplasmic reticulum in cultured rat cardiomyocytes.     

ROS mediates regulation of intracellular Ca2+ induced by angiotensin II in primarily cultured medullary neurons

AIM: To investigate the role of reactive oxygen species (ROS) in the regulation of intracellular Ca²⁺ induced by angiotensin II (Ang II) in the primarily cultured medullary neurons. METHODS: Primarily cultured medullary neurons were prepared from 14-day-old embryos of Sprague-Dawley rats in the study. The identification of medullary neurons was assessed by double-labeling immunofluorescence. To explore the role of ROS, mainly the superoxide (O₂^·), the O₂^·generation was measured using the fluorogenic probe dihydroethidium (DHE). To determine intracellular free calcium concentration ([Ca²⁺]_i), the neurons were loaded with the Ca²⁺-specific dye Fura-2/AM. The cell viability after adding Ang II was also examined using CCK-8 assay. RESULTS: Most of the cultured cells were medullary neurons, more than 80% of which were glutamate positive neurons. Ang II (5 μmol/L) increased the level of ROS within 10 min in the medullary neurons. Ang II at 5 μmol/L induced a significant[Ca²⁺]_i increase in the medullary neurons, and the effect of Ang II occurred rapidly and reached a peak within 20 min after administration. The level of[Ca²⁺]_i started to decline after washout. The Ca²⁺ elevation induced by Ang II was significantly decreased by apocynin or TEMPOL. No significant difference in the cell viability between control group and 5 μmol/L Ang II treatment group was observed. CONCLUSION: ROS is involved in the regulation of[Ca²⁺]_i induced by Ang II in the primarily cultured medullary neurons, suggesting a potential intracellular signaling mechanism involved in the Ang II-mediated oxidant regulation of central neural control of blood pressure.