Hydrogen peroxide mobilizes Ca^2＋ through two distinct mechanisms in rat hepatocytes

Aim： Hydrogen peroxide （H2O2） is produced during liver transplantation. Ischemia/reperfusion induces oxidation and causes intracellular Ca^2＋ overload, which harms liver cells. Our goal was to determine the precise mechanisms of these processes. Methods： Hepatocytes were extracted from rats. Intracellular Ca^2＋ concentrations （[Ca^2＋]i）, inner mitochondrial membrane potentials and NAD（P）H levels were measured using fluorescence imaging. Phospholipase C （PLC） activity was detected using exogenous PIP2. ATP concentrations were measured using the luciferin-luciferase method. Patch-clamp recordings were performed to evaluate membrane currents.
Results： H2O2 increased intracellular Ca^2＋ concentrations （[Ca^2＋]i） across two kinetic phases. A low concentration （400 μmol/L） of H2O2 induced a sustained elevation of [Ca^2＋]i that was reversed by removing extracellular Ca^2＋. H2O2 increased membrane currents consistent with intracellular ATP concentrations. The non-selective ATP-sensitive cation channel blocker amiloride inhibited HRO2-induced membrane current increases and [Ca^2＋]i elevation. A high concentration （1 mmol/L） of H2O2 induced an additional transient elevation of [Ca^2＋]i, which was abolished by the specific PLC blocker U73122 but was not eliminated by removal of extracellular Ca^2＋. PLC activity was increased by 1 mmol/L H2O2but not by 400 μmol/L H2O2.
Conclusions： H2O2 mobilizes Ca^2＋ through two distinct mechanisms. In one, 400 μmol/L H2O2-induced sustained [Ca^2＋]i elevation is mediated via a Ca^2＋ influx mechanism, under which H2O2 impairs mitochondrial function via oxidative stress, reduces intracellular ATP production, and in turn opens ATP-sensitive, non-specific cation channels, leading to Ca^2＋ influx. In contrast, 1 mmol/L H2O2-induced transient elevation of [Ca^2＋]i is mediated via activation of the PLC signaling pathway and subsequently, by mobilization of Ca^2＋ from intracellular Ca^2＋ stores.     

Antioxidative effect of propofol during cardiopulmonary bypass in adults

INTRODUCTION Cardiopulmonary bypass (CPB) can lead to theproduction of damaging oxygen-derived free radicals[1].Some oxygen derivatives such as H2O2 and ·OH areconsidered to have potent oxidative activity to injurehost tissue[2]. These reactive oxygen species cause lipidperoxidation of the cell membrane and intracellular Ca2 overload, which are responsible for mechanical andmetabolic damage . Oxidant injury may be attenuated [3]byendogenous antioxidantdefenses. Antioxidantswithincell …     

Glycine inhibits the LPS-induced increase in cytosolic Ca^2＋ concentration and TNFα production in cardiomyocytes by activating a glycine receptor

Aim： Previous studies have demonstrated that glycine （GLY） markedly reduces lipopolysaccharide （LPS）-induced myocardial injury. However, the mechanism of this effect is still unclear. The present study investigated the effect of GLY on cytosolic calcium concentration （[Ca^2＋]c） and tumor necrosis factor-α（TNFα） production in cardiomyocytes exposed to LPS, as well as whether the glycine-gated chloride channel is involved in this process. Methods： Neonatal rat cardiomyocytes were isolated, and the [Ca^2＋]c and TNFα levels were determined by using Fura-2 and a Quan tikine enzyme-linked immunosorbent assay, respectively. The distribution of the GLY receptor and GLY-induced currents in cardiomyocytes were also investigated using immunocytochemistry and the whole-cell patch-clamp technique, respectively. Results： LPS at concentrations ranging from 10 ng/mL to 100 pg/mL significantly stimulated TNFα production. GLY did not inhibit TNFα production induced by LPS at concentrations below 10 ng/mL but did significantly decrease TNFα release stimulated by 100 pg/mL LPS and prevented an LPS-induced increase in [Ca^2＋]c, which was reversed by strychnine, a glycine receptor antagonist. GLY did not block the isoproterenol-induced increase in [Ca^2＋]c, but did prevent the potassium chloride-induced increase in [Ca2＋]cin cardiomyocytes. Strychnine reversed the inhibition of the KCl-stimulated elevation in [Ca^2＋]cby GLY. In chloride-free buffer, GLY had no effect on the dipotassium hydrogen phosphate-induced increase in [Ca^2＋]c. Furthermore, GLY receptor α1 and β subunitimmunoreactive spots were observed in cardiomyocytes, and GLY-evoked currents were blocked by strychnine. Conclusion： Cardiomyocytes possess the glycine-gated chloride channel, through which GLY prevents the increase in [Ca^2＋]c and inhibits the TNFα production induced by LPS at high doses in neonatal rat cardiomyocytes.     

Effects of Panax notoginseng saponins on vascular endothelial cells in vitro

AIM: To investigate the inhibition of endothelium-de-pendent in vitro vascular relaxation induced by the total saponins (gensenosides) from Panax notoginseng (PNS) and the effect of PNS on the cytosolic Ca2 concentration on cultured bovine pulmonary artery endothelial cells. METHODS: The endothelial-dependent vascular relaxation was assessed using acetylcholine (ACh) or cyclopi-azonic acid (CPA) induced relaxation in endothelium-intact rat aorta. Cytosolic Ca2 level was assessed in real time using dynamic digital fluorescence ratio imaging. RESULTS: In addition to its direct relaxation of the smooth muscle cells at high concentrations, PNS, at 100 mg/L having little effect on smooth muscle, caused a marked inhibition of endothelium-dependent relaxation brought about by PNS. This inhibitory effect was due to its inhibition of elevation of cytosolic Ca2 , which is required for the activation of NO generation and release from the vascular endothelial cells. Nifedipine has no effect on either the endothe     

Effect of total flavonoids of dracocephalum heterophyllum benth on norepinephrine-induced cardiomyocyte hypertrophy in rats北大核心CSCD

OBJECTIVE: To study the effect of total flavonoids of Dracocephalum heterophyllum (TFDH), a Uygur medicine, on cardiomyocyte hypertrophy induced by norepinephrine (NE), and to provide insights into the mechanism. METHODS: Cardiomyocytes of primarily cultured neonatal rats were used as models. Myocardial hypertrophy was induced by NE 2 umol · L-1. The cells were divided into cell control group, NE 2 umol-L-1 model group, and TFDH 10, 25 and 50 umol-L-1+NE 2 umol-L-1 groups. CCK-8 method was used to observe the activity of myocardial cells, while RT-PCR technique was used to detect the expression of mRNA of cardiac hypertrophy gene atrial natriuretic peptide (ANP) and β-myosin heavy chain (β-MHC). The internal factors were glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Confocal laser scanning was used to detect the surface area of myocardial cells and [Ca2+]. The activity of Ca2+-ATP was measured with enzymatic reaction of fragmentation cells. The concentration of NO and the activity of NOS were determined with colorimetry. RESULTS: Compared with the cell control group, cardiomyocytes were stimulated at 48 h by NE 2 umol · L-1 which could decrease the survival rate of cardiomyocytes from (95±1)% to (78+5)%, surface area increased from (178±29) μm2 to (274±38) μ2 (P<0.05), the expression of mRNA of ANP and β-MHC increased from (1.00±0.01) and (1.00±0.02) to (2.76±0.55) and (2.69±0.31), respectively (P<0.05). The concentration of [Ca2+], increased from 1.00±0.12 to (1.52 ± 0.41) umol-L-1, while the activity of Ca2+-ATP decreased from 1.01±0.14 to (0.41±0.06) umol-L-1 (P<0.05). The concentration of NO decreased from 1.50±0.14 to (1.12±0.05) umol-L-1, and the activity of NOS decreased from 0.86±0.06 to (0.52±0.10) μmol-L-1 (P<0.05). TFDH 10, 25 and 50 μmol · L-1 could inhibit the decline of the survival rate, increase of the surface area and the increased expressions of mRNA of ANP and β-MHC that were induced by NE (P<0.05). At the same time, it also could inhibit the increase of the concentration of [Ca2+], the decreased of activity of Ca2+-ATP, and the decline of the concentration of NO and the activity of NOS (P<0.05). CONCLUSION: TFDH can improve the activity of cardiomyocyte hypertrophy induced by NE, down-regutate mRNA expressions of proto oncogene ANP and β-MHC, and reduce the surface area of cardiomyocytes induced by NE. The mechanism may be related to promoting the release of NO and regulating the concentration of [Ca2+], and the activity of Ca2+-ATP. © 2017 Chinese Journal of Pharmacology and Toxicology. All rights reserved.     

Anti-amnestic and anti-aging effects of ginsenoside Rg1 and Rb1 and its mechanism of action

In the present paper, we overview the discovery of new biological activities induced by ginsenoside Rg 1 and Rb 1 and discuss possible mechanisms of action. Both compounds could increase neural plasticity in efficacy and structure; especially Rg 1, as one small molecular drug, can increase proliferation and differentiation of neural progenitor cells in dentate gyrus of hippocampus of normal adult mice and global ischemia model in gerbils. This finding has great value for treatment of Alzheimer‘s disease and other neurodegenerative disorders which is characterized by neurons loss. Increase of expression of brain derived neurotrophic factor, Bcl-2 and antioxidant enzyme, enhanced new synapse formation, inhibition of apoptosis and calcium overload are also important neuron protective factors. Rgl and Rbl have common effects, but there are some differences in pharmacology and mechanism. These differences may attribute to their different chemical structure. Rg 1 is panaxtriol with two sugars, while Rb 1 is panaxtriol with four sugars     

Initial study on apoptosis in HepG-2 Human heptocarcinoma cell line by CSS

Objective To discuss on mechanism of the killing and apoptosis inducing effect induced by total alkaloid in the CSS(Capparis spinosa L.saponin,CSS)on human hepatocarcinoma cell Line HepG-2.Methods The killing effect of the CSS on human hepatocarcinoma cell Line HepG-2 was observed by MTT method.Morphological observation of the HepG-2 cells was completed by fluorescence microscope.This test was signed to observe the changes of the cell cycle of HepG-2 cells affected by the CSS by PI single-staining,and to observe if there were typical apoptosis peaks.The apoptosis inducing effect and changing of mitochondria membrane potential of the CSS on the HepG-2 cells were studied by flow cytometry.The effect of intracellular Ca2+ level of CSS on the HepG-2 cells was measured by laser confocal microscope.Results CSS has growth inhibiting on the HepG-2 and seems to be enhanced with the increasing concentration of CSS,and its IC50 value was 46.16 μg·mL-1.The HepG-2 cells are characteristic apoptosis morphologic changed,and the apoptosis percentage is increased to 66.652% in the 50 μg·mL-1 dosage group.The cells cycle has been changed obviously that the progresses of cells cycle of G1 period and G2 period in high dosage group have been blocked,and the cellular proportion in G2 period is decreased by the function of CSS for 24 h.The mitochondria membrane potential of HepG-2 cells induced by CSS is decreased in various degrees.In addition,the intracellular Ca2+ level is increased by the function of CSS in the middle and high dose groups.Conclusions The CSS has obviously killing and apoptosis inducing effect on human hepatocarcinoma cell Line HepG-2 by the mechanism of decreasing the mitochondria membrane potential and increasing the intracellular Ca2+ level.     

粉防己碱特异抑制大鼠血小板聚集和ATP释放(英文)

AIM: To examine the effects of tetrandrine (Tet) on the aggregation and ATP-release of rat washed platelets induced by several platelet activators. METHODS: Gel-filtration (Sepharose 2B) was used to isolate washed platelets from adult rats and the platelet aggragation and ATP-release were measured simultaneously. RESULTS: In the presence of Ca2 1 mmol · L-1, Tet 300 μmol·L -1 inhibited the aggregation induced by ADP ( 25 μmol · L -1), collagen (2.5 g·L-1), and thrombin (103 unit·L-1) by 62 %, 60 %, and 34 %, respectively. It also inhibited arachidonic acid (1 mmol · L-1)-induced aggregation. Elevating intracellular Ca2 concentration with the Ca2 ionophore, calcimycin (30 μmol · L-1), or by blocking the intracellular calcium pump with cyclopiazonic acid (5 μmol · L-1) initiated platelet aggregation, which was also inhibited by Tet. In Ca2 -free medium, Tet still elicited an inhibitory effect on aggregation induced by ristocetin (2.5 g·L-1). Lower concentrations of Tet (30 nmol·L-1 to     

Causative and preventive action of calcium in cataracto-genesis

Calcium and Ca-dependent enzymes play specific role in the development of human cataracts. Entry of Ca2 into the lens epithelial cells (LEC) is highly regulated by quantum of receptors. The Ca2 level controls homeostasis and growth of entire lens. Intracellular overload of Ca2 in the LEC trigger a series of events such as activation of Ca-dependent enzymes, irreversible breakdown of important structural proteins and cell death. Proper maintenance of Ca2 levels by regulating activity of Ca-pumps and Ca-channels and inhibition of Ca-dependent enzymes can help in prevention of cataract. Induction of cell death in the LEC by increase in the intracellular Ca2 may be utilized for the prevention of posterior capsular opacification.     

Mechanism of regulation of CaCC by the Mas-related G protein-coupled receptor D

MrgD is expressed almost exclusively in dorsal root ganglion(DRG) neurons.And its activation inhibited KCNQ/M-currents that contributes to an increase in excitability of DRG neurons and thus may enhance the signaling of primary afferent nociceptive neurons.Ca2+-activated chloride channels(CaCCs) are found in DRG neurons and regulate neuronal cell excitability as well.But the interaction between CaCCS and MrgD is still unknown.We here found that β-alanine-induced activation of MrgD resulted in eliciting Ca2+-activated chloride currents.The currents were inhibited by flufenamic acid(FFA) and by inhibition of phospholipase C and Ca2+ chelating agent EGTA.However,calphostin C,a PKC inhibitor,had no effect on the currents.These present data show that the inward currents induced by activation of MrgD were mediated through Gq-phospholipase C-IP3-Ca2+ release pathway,but not via Gi pathway.     

无创性肢体缺血预适应对大鼠心肌缺血/再灌损伤后心肌凋亡的影响

目的观察无创性肢体缺血预适应(NLIP)对心脏缺血/再灌损伤后心肌凋亡的影响而进一步探讨其对心脏的延迟保护作用。方法通过连续3 d每天1次,3个循环下肢无创性5 min缺血5 min再灌建立NLIP模型。实验分3组:心肌缺血/再灌组(I/R)、心脏缺血预适应组(IP)、NLIP组。再灌末取心肌组织,以四氮唑染色法测定心肌梗死面积(IS/AAR×100%);以TUNEL法检测细胞凋亡并且用免疫组织化学法检测凋亡基因的表达;分离心肌细胞,用流式细胞仪检测细胞凋亡率以及凋亡基因表达率。结果与I/R组(47.6%±7.5%)比较,IP和NLIP能明显降低梗死面积(24.6%±8.7%和23.1%±7.4%,P<0.01);流式细胞仪检测结果表明,在I/R组,细胞凋亡率高(16.21%±2.12%),Bcl-2/Bax比值低(0.66±0.03),IP和NLIP能明显降低细胞凋亡率(5.30%±0.81%,4.82%±1.15%,P<0.01),提高Bcl-2/Bax的比值(1.44±0.08,1.51±0.09,P<0.01);免疫组化染色结果与其一致。结论NLIP对心肌缺血/再灌损伤具有保护作用,机制可能与其对抗心肌细胞凋亡有关。     

脂联素对大鼠缺血/再灌注心肌细胞凋亡及相关蛋白表达的影响

目的观察脂联素(adiponectin,APN)对大鼠缺血/再灌注(ischemia/reperfusion,I/R)诱导的心肌细胞凋亡与凋亡相关蛋白Bcl-2、Bax、Caspase-3表达的影响。方法将48只大鼠随机分成假手术组(sham group)、I/R组(I/R group)、脂联素预处理组(APN+I/R group),每组16只。结扎左冠状动脉前降支,建立大鼠心肌I/R模型。各组随机选取8只,采用Evans blue-TTC双染法测定心肌梗死面积;另外8只对心功能指标进行监测,实验结束后,采用透射电镜观察心肌组织损伤;原位末端标记(TUNEL)法观察心肌细胞凋亡情况;Western blot法测定心肌Bcl-2、Bax、Caspase-3蛋白的表达。结果脂联素明显减小I/R所致的大鼠心肌梗死面积(P<0.05),改善心脏血流动力学(P<0.05),减轻透射电镜下心肌细胞形态、细胞膜、细胞核、线粒体等结构改变,减少细胞凋亡,增加Bcl-2表达(P<0.05),降低Bax与Caspase-3蛋白表达(P<0.05)。结论脂联素对I/R损伤的保护作用与抑制心肌细胞凋亡,从而减少心肌细胞损失、减轻心脏功能障碍有关,其抗凋亡作用机制可能与上调Bcl-2表达,下调Bax及Caspase-3表达有关。     

吡那地尔后处理在减轻家兔心肌缺血/再灌注损伤中的作用

目的观察吡那地尔后处理在减轻家兔在体心肌缺血/再灌注损伤的作用,并探讨其可能机制。方法 40只健康成年♂家兔随机分为5组(每组8只),分别为假手术组(Sham)、缺血再灌组(I/R)、缺血后处理组(I-postC)、吡那地尔后处理组(Pina)、吡那地尔后处理+5-羟葵酸组(Pina+5-HD)。采用结扎左冠前降支30 min/复灌120 min的方法复制心肌缺血/再灌注损伤模型。观察并比较各组动物在缺血前、缺血30 min、复灌120 min时心功能指标、血浆CK活性和MDA含量。测定心肌缺血和梗死面积,Bcl-2和Bax mR-NA的表达。结果在复灌120 min时,与I/R组和Pina+5-HD组相比,I-postC组和Pina组动物LVSP明显升高(P<0.05);LVEDP明显降低(P<0.05);血浆CK活性明显降低(P<0.05);血浆MDA含量明显降低(P<0.05);心肌梗死面积明显减小(P<0.05);Bcl-2 mRNA的表达明显增加,BaxmRNA的表达明显降低(P<0.05)。结论吡那地尔后处理可通过模拟缺血后处理的心肌保护机制,减轻心肌缺血/再灌注损伤,其心肌保护的机制可能涉及线粒体ATP敏感性钾通道开放,Bcl-2 mRNA表达的上调和Bax mRNA表达的下调。     

Cardioprotection from ischemia and reperfusion injury by an endothelin A-receptor antagonist in relation to nitric oxide production

It has previously been shown that endothelin (ET)-receptor antagonists protect the myocardium from ischemia and reperfusion (I/R) injury. The mechanism behind this effect is unclear. The aim of this study was to elucidate the possible interaction between ET(A)-receptor antagonism and nitric oxide (NO) during I/R. Anesthetized pigs were subjected to 45-min ligation of the left anterior descending coronary artery (LAD) followed by 4 h of reperfusion. Vehicle (n = 7), the ET(A)-receptor antagonist LU 135252 (LU; 0.1 mg/kg, n = 7), the combination of LU and the NO precursor L-arginine (15 mg/kg, n = 7; LU + L-arg), the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA; 0.2 mg/kg, n = 6), or the combination of LU and L-NMMA (LU + L-NMMA; n = 6) were injected into the LAD during the last 10 min of ischemia and the first 5 min of reperfusion. There were no significant differences in coronary flow, pulmonary capillary wedge pressure, mean arterial pressure, or heart rate between the groups before ischemia or at the end of reperfusion. The area at risk was similar in all five groups. The infarct size of the vehicle group was 79 +/- 6% of the area at risk. LU and LU + L-arginine (L-arg) reduced the infarct size to 39 +/- 6% and 35 +/- 8%, respectively (p < 0.001 vs. vehicle). L-NMMA completely prevented the infarct-limiting effect of LU. Thus the infarct size in the LU + L-NMMA group was 83 +/- 4% (p < 0.001 vs. LU alone); L-NMMA did not affect infarct size per se (79 +/- 4%). ET immunoreactivity increased threefold in the I/R myocardium of the vehicle group. The increase in ET immunoreactivity was significantly attenuated in the LU and LU + L-arg groups (p < 0.001), but not in the groups given L-NMMA or LU + L-NMMA. In conclusion, ET(A)-receptor blockade results in cardioprotection and attenuation of the increase in myocardial ET levels after I/R. Both effects were inhibited by NO synthase blockade, suggesting that they are dependent on maintained production of NO.     

3',4'-Dihydroxyflavonol reduces infarct size and injury associated with myocardial ischaemia and reperfusion in sheep

1 The antioxidant properties of flavonols in vivo and their potential benefits in myocardial ischaemia/reperfusion (I/R) injury have been little investigated. We evaluated the ability of a synthetic flavonol, 3',4'-dihydroxyflavonol (DiOHF) to scavenge superoxide in post-I/R myocardium and to prevent myocardial I/R injury. 2 Anaesthetized sheep were studied in four groups (n=5-6): control, ischaemic preconditioning (IPC), vehicle and DiOHF (before reperfusion, 5 mg kg(-1), i.v.). The left anterior descending coronary artery was occluded distal to the second diagonal branch for 1 h followed by 2 h of reperfusion. Infarct size, myocardial function, NADPH-activated superoxide generation and biochemical markers of injury were measured. 3 DiOHF (10(-8)-10(-4) m) incubated in vitro with post-I/R myocardium from the vehicle group suppressed superoxide production dose-dependently. 4 DiOHF administered in vivo also significantly reduced superoxide generation in vitro. DiOHF and IPC markedly reduced infarct size, which was 73+/-2% of the area at risk in vehicle, 50+/-4% in DiOHF, 75+/-5% in control and 44+/-4% in IPC. Post-I/R segment shortening within the ischaemic zone was greater in DiOHF (2.3+/-0.7%; P<0.01) and IPC (1.7+/-0.5%; P<0.01) than those in corresponding controls (-1.7+/-0.4; -2.1+/-0.4%). 5 DiOHF and IPC improved coronary blood flow to the ischaemic area and preserved higher levels of nitric oxide metabolites in the venous outflow from the ischaemic zone. 6 DiOHF attenuated superoxide production in post-I/R myocardium, and significantly reduced infarct size and injury following I/R in anaesthetized sheep. The extent of protection by DiOHF is comparable to that afforded by IPC. Thus, DiOHF has clinical potential for improving recovery from acute myocardial infarction and other ischaemic syndromes.     

巴曲酶对抗狗心脏缺血/再灌损伤(英文)

目的:研究巴曲酶(Bat)对狗心脏缺血/再灌损伤的影响。方法:狗冠脉左前降枝结扎30 min后恢复血液灌注,于缺血前(Bat-Ⅰ组)或缺血后再灌前15min(Bat-Ⅱ组)静脉注射Bat(1 Bu·kg~(-1))。测定dp/dt_(max)和LVEDP及血浆CK和LDH及心肌MDA含量,观察心肌病理形态学改变。结果:I/R组动物缺血或再灌后死亡率高达65.0％,心肌损伤明显。Bat-Ⅰ和Bat-Ⅱ组动物的死亡率分别为30.0％和28.6％,P<0.05,心肌损伤减轻;血浆CK、LDH含量,LVEDP及心肌MDA含量降低; dp/dt_(max)和-dp/dt_(max)增加。结论:Bat可明显拮抗狗心脏缺血/再灌注损伤,改善心功能。     

Estrogen alone or combined with medroxyprogesterone but not raloxifene reduce myocardial infarct size

We investigated whether estrogen protects the ischemic myocardium in oophorectomized female rabbits fed with a cholesterol-enriched diet, whether the addition of a progestin compound attenuates the beneficial effect of estrogen and whether raloxifene also limits myocardial necrosis. We treated 32 female oophorectomized hypercholesterolemic rabbits with (a) placebo (N=8, group I), (b) conjugated estrogens alone (N=8, group II), (c) conjugated estrogens combined continuously with medroxyprogesterone acetate (N=8, group III) and (d) raloxifene (N=8, group IV) all for 4 weeks. All rabbits underwent 30 min of ischemia and 120 min of reperfusion. Both infarct size (0.38+/-0.08 and 0.45+/-0.05 in groups II and III, respectively, vs. 0.78+/-0.07 in group I, P<0.005) and infarct size/risk zone% (26.34+/-4.18 and 35.01+/-4.39 in groups II and III, respectively, vs. 52.18+/-7.84 in group I, P<0.05) were significantly smaller in the estrogen treatment groups compared to placebo. No significant difference was observed between groups II and III. There was no significant difference between groups I and IV for infarct size (0.78+/-0.07 vs. 0.69+/-0.08, respectively) or for infarct size/risk zone% (52.18+/-7.84 vs. 47.17+/-4.3). Short-term estrogen protects ischemic myocardium in hypercholesterolemic oophorectomized female rabbits; this effect is not attenuated by the addition of a progestin compound. Raloxifene, however, does not decrease infarct size compared to placebo.     

Tribulosin protects rat hearts from ischemia/ reperfusion injury

Aim:

To investigate the protective effect of tribulosin, a monomer of the gross saponins from Tribulus terrestris, against cardiac ischemia/reperfusion injury and the underlying mechanism in rats.

Methods:

Isolated rat hearts were subjected to 30 min of ischemia followed by 120 min of reperfusion using Langendorff''s technique. The hearts were assigned to seven groups: control, ischemia/reperfusion (I/R), treatment with gross saponins from Tribulus terrestris (GSTT) 100 mg/L, treatment with tribulosin (100, 10, and 1 nmol/L) and treatment with a PKC inhibitor (chelerythrine) (1 μmol/L). Infarct size was assessed by triphenyltetrazolium chloride staining. Malondialdehyde (MDA), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) contents as well as superoxide dismutase (SOD) and creatine kinase (CK) activities were determined after the treatment. Histopathological changes in the myocardium were observed using hematoxylin-eosin (H&E) staining. Apoptosis was detected with terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) assay. Bcl-2, Bax, caspase-3, and PKCɛ protein expression were examined using Western blotting.

Results:

Tribulosin treatment significantly reduced MDA, AST, CK and LDH contents, and increased the activity of SOD. The infarct size of I/R group was 40.21% of the total area. GSTT and various concentrations of tribulosin treatment decreased the infarct size to 24.33%, 20.24%, 23.19%, and 30.32% (P<0.01). Tribulosin treatment reduced the myocardial apoptosis rate in a concentration-dependent manner. Bcl-2 and PKCɛ protein expression was increased after tribulosin preconditioning, whereas Bax and caspase-3 expression was decreased. In the chelerythrine group, Bcl-2 and PKCɛ expression was decreased, whereas Bax and caspase-3 expression was increased.

Conclusion:

Tribulosin protects myocardium against ischemia/reperfusion injury through PKCɛ activation.     

氯沙坦对大鼠心肌缺血再灌注损伤的影响

目的:观察血管紧张肽II1型受体阻断剂 氯沙坦对大鼠缺血再灌注心肌的梗死面积、心肌结 构、肿瘤坏死因子α(TNF α)、白细胞介素6(IL 6) 的影响。方法:雄性Sprague Dawley(SD)大鼠42只 随机分为4组:对照组、缺血再灌注组、氯沙坦 5mg·kg-1组和氯沙坦10mg·kg-1组。除对照组 外,余3组建立心肌缺血再灌注模型,2个氯沙坦组 分别于缺血前15min静脉注射氯沙坦5,10mg· kg-1。计算心肌梗死范围,观察心肌细胞超微结构, 检测再灌注后血浆TNF α和IL 6的浓度。结果:与 缺血再灌注组相比,2氯沙坦组梗死面积减小(P< 0.01),心肌超微结构改善。缺血再灌注组TNF α 和IL 6的浓度均明显高于对照组(P<0.01);2个 氯沙坦组TNF α和IL 6的浓度均低于缺血再灌注 组(P<0.01),其中氯沙坦10mg·kg-1组较 5mg·kg-1组的浓度低(P<0.05,P<0.01)。结 论:氯沙坦具有抗大鼠心肌缺血再灌注损伤的作用, 高剂量氯沙坦的效果明显,其机制可能与从受体水 平阻断肾素 血管紧张肽系统,减少炎性因子TNF α和IL 6的产生有关。     

Calpain inhibitor-1 reduces infarct size and DNA fragmentation of myocardium in ischemic/reperfused rat heart

Myocardial ischemia/reperfusion activates a calcium-dependent protease, calpain, in the ischemic myocytes. It is not known whether calpain is involved in the mechanism of ischemia/reperfusion injury in hearts. Thus the purpose of this study was to clarify the effect of a selective calpain inhibitor (CAI) on infarct size and the extent of DNA damage in ischemic/reperfused rat hearts. Rats were divided in four groups (n = 7 each). In saline group, 0.3 ml of saline was administered (i.v.) 10 min before 30-min coronary occlusion followed by 6-h reperfusion. In vehicle group, 0.3 ml of 10% dimethyl sulfoxide (DMSO) was administered 10 min before the 30-min ischemia. CAI (0.5 mg/kg) was administered 10 min before the 30-min ischemia (CAI-A group) and 10 min before the 6-h reperfusion period (CAI-B group). Infarct size was detected with triphenyl tetrazolium chloride, and DNA fragmentation was detected by agarose gel electrophoresis and by in situ nick end labeling (ISEL). Infarct size was significantly smaller in the CAI-A group compared with the vehicle group (13+/-9% vs. 48+/-12%; p < 0.01), and the incidence of ISEL-positive myocyte nuclei in the subendocardial region was significantly reduced in the CAI-A group compared with the vehicle group (26+/-3% vs. 59+/-6%; p < 0.01). However, the effects of CAI in CAI-B group were not significant. Activation of calpain is involved in the mechanism of ischemia/reperfusion injury, and the preischemic administration of CAI was effective in reducing myocardial infarct size and the DNA damage of the myocytes in ischemic/reperfused rat heart.