Methyl Jasmonate-induced Increase in Intracellular Magnesium Promotes Apoptosis in Breast Cancer Cells.

BACKGROUND/AIM: Methyl jasmonate (MeJa) is a botanical stress hormone that serves as a defense mechanism to inhibit growth in stressed plants. It is well known that MeJa exhibits an anticancer effect by reducing intracellular ATP, activating reactive oxygen species (ROS) production, and promoting mitogen-activated protein kinase (MAPK) activity. Presently, no report has been published on MeJa-induced changes in intracellular Mg2+ concentration ([Mg2+]i), and TRPM7 as an Mg2+ transporter in cancer cells. Therefore, this study aimed to investigate the Mg2+ homeostatic changes and apoptotic effects following MeJa treatment using the MCF-7 human breast cancer cell line. MATERIALS AND METHODS: The MTT assay was used to assess the cell viability and half-inhibitory concentration, microscopic two-photon excitation wavelength spectrophotometry was used to measure the [Mg2+]i, a luminescent assay determined intracellular ATP levels, western blot assay measured TRPM7 levels, antioxidant capacities, endoplasmic reticulum (ER) stress, and MAPK signaling pathways, while the fluorescence assay evaluated ROS concentrations and the cell apoptotic index. RESULTS: This study provides evidence that MeJa has an antiapoptotic effect on MCF-7 cells. The increase in [Mg2+]i led to decreased TRPM7 expression, which is related to elevated ROS production, in addition to elevated ER stress and MAPK signaling pathway activity and decreased ATP content. CONCLUSION: The increase in [Mg2+]i leads to decreased TRPM7 expression and may be the epicenter of MeJa-induced apoptotic cell death in MCF-7 cells.

Application of Patient-Specific Instrumentation in a Dog Model with Antebrachial Growth Deformity Using a 3-D Phantom Bone Model.

One of the most frequent bone deformities in dogs is antebrachial growth deformity (AGD), which results from malunion of the distal growth plates. The objective of the present study was to re-align the limbs, which can correct the length mismatch and reset the coherence of the joint with the aid of a 3-D phantom model for surgical preplanning. A 14-month-old, intact female Golden Retriever with an angular deformity of the left radius and ulna was selected for the study. The diagnosis was confirmed by orthogonal radiographs. Moreover, computed tomography (CT) scans revealed a multiplane deformity with valgus, procurator, and external rotation of the left radius. The pre-surgical planning started with the quantification of the angular deformity, followed by a simulated virtual osteotomy, and concluded with an in vitro rehearsal surgery on 3-D printed phantom bone models. In the operating room, prefabricated patient-specific instrumentation (PSI) was attached at the planned site of the radial bone surface for a precise closing wedge osteotomy. Then two locking plates were fixed routinely. Post-operative radiographs showed accurate correction of the deformity as we had planned. At 12 weeks post-operatively, the follow-up surveys revealed improved gait, weight-bearing, and progression of bone healing. Our PSI design, based on novel surgical planning, was steady yet straightforward during the osteotomy. The osteotomy was performed without difficulty since the PSI that pre-determined the sites and angles let the surgeon perform the antebrachial malformation surgery. This method of operation reduces stress on the operator and helps to improve accuracy, repeatability, and surgery time.

Myocardial calcification and hypertension following chronic renal failure and ameliorative effects of furosemide and captopril.

OBJECTIVES: The aim of this study was to prevent metastatic myocardial calcification and hypertension following chronic renal failure (CRF). METHODS: A total of 50 male Sprague-Dawley rats were allocated to one of five groups: the control group (sham), the NxNT group (nephrectomized rats receiving no treatment), the NxFuro group (nephrectomized rats treated with furosemide), the NxCap group (nephrectomized rats treated with captopril) and the NxFuroCap group (nephrectomized rats treated with furosemide and captopril). Surgery (5/6 nephrectomy) was performed to induce CRF. Oral treatment with furosemide (20 mg/kg) and/or captopril (0.05 mg/kg) was given twice daily for 5 weeks. Parameters were studied after 5 weeks. RESULTS: In the NxNT group, arterial blood pressure was significantly increased compared with the controls. Monotherapy with furosemide or captopril and both in combination maintained blood pressure to near or below control. Myocardial and remnant-kidney calcification was detected in NxNT rats, but calcification was absent in the NxFuroCap rats. Cardiac hypertrophy and fibrosis was observed in the NxNT group but not in treatment groups. Both plasma inorganic phosphate and Ca(2+) significantly increased in the NxNT group, but the difference was not significant in the treatment groups. CONCLUSION: Furosemide, either alone or in combination with captopril, is capable to prevent myocardial calcification, cardiac hypertrophy and hypertension, maintaining blood Ca(2+) and phosphate levels by slowing CRF.

Aralia continentalis kitagawa Extract Attenuates the Fatigue Induced by Exhaustive Exercise through Inhibition of Oxidative Stress.

The present study aimed to evaluate the anti-fatigue effects of Aralia continentalis kitagawa (AC) extract during exhaustive exercise of rats by forced swimming. Rats were subjected to forced swimming until exhausted after pre-treatment with AC extract for 21 days. Exhaustion time significantly increased in rats treated with AC extract. AC treatment also preserved blood homeostasis during fatigue due to exhaustive exercise. For fatigue-related serum biomarkers, AC extract significantly fail to decrease glucose and triglyceride (TG), but ameliorated increased lactate levels compared with levels in control rats. Metabolic acidosis, a major cause of fatigue, was effectively attenuated by AC extract, according to metabolic acidosis-related blood parameters. AC extract suppressed muscle injury and attenuated gastrocnemius muscle apoptotic responses due to exhaustive exercise. To investigate the mechanisms behind the AC extract anti-fatigue effect, we evaluated its effect on oxidative stress-related fatigue. We showed that pro-oxidants were inhibited, while antioxidants were preserved by AC extract treatment. Therefore, the anti-fatigue effect of AC extract was mediated by suppression of oxidative stress. Overall, the study demonstrated that AC extract effectively attenuates fatigue from exhaustive exercise through oxidative stress inhibition. AC extract, as an antioxidant, could be utilized as a therapeutic or preventive strategy against exhaustive exercise fatigue.

An Easy and Economical Way to Produce a Three-Dimensional Bone Phantom in a Dog with Antebrachial Deformities.

3-D surgical planning for restorative osteotomy is costly and time-consuming because surgeons need to be helped from commercial companies to get 3-D printed bones. However, practitioners can save time and keep the cost to a minimum by utilizing free software and establishing their 3-D printers locally. Surgical planning for the corrective osteotomy of antebrachial growth deformities (AGD) is challenging for several reasons (the nature of the biapical or multiapical conformational abnormalities and lack of a reference value for the specific breed). Pre-operative planning challenges include: a definite description of the position of the center of rotation of angulation (CORA) and proper positioning of the osteotomies applicable to the CORA. In the present study, we demonstrated an accurate and reproducible bone-cutting technique using patient-specific instrumentations (PSI) 3-D technology. The results of the location precision showed that, by using PSIs, the surgeons were able to accurately replicate preoperative resection planning. PSI results also indicate that PSI technology provides a smaller standard deviation than the freehand method. PSI technology performed in the distal radial angular deformity may provide good cutting accuracy. In conclusion, the PSI technology may improve bone-cutting accuracy during corrective osteotomy by providing clinically acceptable margins.

The antioxidant, taurine reduced lipopolysaccharide (LPS)-induced generation of ROS, and activation of MAPKs and Bax in cultured pneumocytes.

Lipopolysaccharide (LPS) can cause damage to the epithelia of the respiratory tract. However, taurine can protect the lung tissue from such oxidant-induced inflammation. This study examined the effects of a LPS treatment on the intracellular calcium levels ([Ca(2+)]i) as well as the specific mechanisms of LPS-induced cell death in pneumocytes. In addition, the effects of taurine on the LPS-induced increase in the accumulation of reactive oxygen species (ROS) in pneumocytes were investigated. The [Ca(2+)]i in cultured pneumocytes was determined using microfluorescence techniques. The level of activation of the mitogen-activated protein kinases (MAPKs) and Bax protein were measured by Western blotting. LPS at 10 and 100 ng/ml induced cell death and decreased the viability of MRC-5 cells. Moreover, the intracellular Ca(2+) and ROS levels were increased by LPS. The LPS treatment led to the phosphorylation of ERK1/2, JNK and the activation of Bax. A pretreatment with 20 mM taurine reduced the LPS-induced production of ROS and MARK activity. These results show that a LPS treatment induces cell death in MRC-5 cells by increasing the intracellular ROS and Ca(2+) levels. The increase in the intracellular level of ROS promotes MAPKs activation and Bax translocation. Overall, LPS induces lung cell death by activating MAPKs. Furthermore, taurine decreased the LPS-induced generation of ROS and activation of MAPK and Bax.

Immunosuppressant FK506 decreases the intracellular magnesium in the human osteoblast cell by inhibiting the ERK1/2 pathway.

AIMS: Previous studies reported that FK506 influences bone mineralizing and hypomagnesemia, and also has immune modifying properties. This study examined whether or not the function of Mg2+ in bone metabolism plays a role in the loss of bone volume caused by immunosuppressants. MAIN METHODS: The effects of the FK506 treatment on the intracellular magnesium and lactate dehydrogenase (LDH) activity were examined in cultured human osteoblasts (HOB) cells. The magnesium concentration was determined using microfluorescence techniques and atomic absorption spectrophotometry. Western blotting was used to measure the level of extracellular signal-regulated kinases 1/2 (ERK 1/2) activation. KEY FINDINGS: FK506 (0.1 microM) did not affect cell death in HOB cells after a 24 hour treatment but decreased the level of ERK 1/2 activation. In HOB cells, the mean [Mg2+]i after exposure to a 1 mM extracellular Mg2+ ([Mg2+]o) buffer was 0.53+/-0.01 mM (n=25). Exposure to 100 nM FK506 produced a significant decrease in [Mg2+]i (0.41+/-0.01 mM). The ERK inhibitor (PD98059) and FK506 produced similar effects but they were not cumulative. SIGNIFICANCE: This study examined the role of ERK1/2 activation on the regulation of magnesium in HOB. These results suggest that the inhibition of ERK phosphorylation is an essential intermediate in the effects of FK506 on magnesium. Overall, FK506 causes bone disorders partly by decreasing [Mg2+]i accompanied by the inhibition of ERK 1/2.

Red Ginseng Reduces Inflammatory Response via Suppression MAPK/P38 Signaling and p65 Nuclear Proteins Translocation in Rats and Raw 264.7 Macrophage.

Lipopolysaccharides (LPS) cause systemic inflammatory responses, which are characterized by high mortality and multiple signs, including metabolic disturbances, respiratory acidosis, hypotension, and vital organs disorder. Cytokines secretion and oxidative stress are the main features of the disease. Diagnosis and treatment of systemic inflammation (SI) remain a challenge. Korean Red Ginseng (RG) is one of medicinal herbs that showed a potent anti-oxidant effect. We aimed to study the protective effects of RG on systemic inflammatory response in rats and RAW 264.7 macrophage cells induced by LPS. The rats were treated with water and alcohol extracts of RG for four weeks to prevent the inflammatory response. The result showed that LPS toxin increased morbidity and mortality, and induced liver, kidney, and lung injuries manifested by deteriorated biomarkers. Hypotension, hypomagnesemia, acidosis, and oxidative stress were observed in septic rats. However, RG extracts attenuated liver, kidney, and lung enzymes and metabolites in treated groups via its anti-inflammatory and anti-oxidant properties. Furthermore, RG improved magnesium and blood pressure in the treated groups. RAW 264.7 macrophage cells exposed to LPS disturbance in translocation of p65 and MAPK/p38. Nevertheless, RG-pretreated cells did not significantly alter. In conclusion, RG reduced the rates of mortality and morbidity of treated rats - liver, kidney, and lung injuries were protected in the treated groups through the potentiation of anti-oxidant defense. RG was able to conserve mitochondrial function, inhibiting the activation of MAPK/p38 signaling and suppressing NF-κB p65 cytoplasm-nucleus transport. Further studies are needed to examine the effects on chronic conditions in animal models and human.

Long-term oral intake of Panax ginseng improves hypomagnesemia, hyperlactatemia, base deficit, and metabolic acidosis in an alloxan-induced rabbit model.

OBJECTIVES: Panax ginseng (PG) widely used for its various pharmacological activities, including effects on diabetes and its complications. This study aims to investigate the effect of PG on mortality-related hypomagnesemia, hyperlactatemia, metabolic acidosis, and other diabetes-induced abnormalities. MATERIALS AND METHODS: Type 1 diabetes was induced by IV injection of alloxan monohydrate 110 mg/kg into New Zealand white rabbits weighing 2-2.5 kg. PG was supplied in drinking water for 20 weeks. The effects of the PG treatment on diabetes were evaluated through hematological and biochemical analysis including ELISA assays for insulin and glycated haemoglobin A1c (HBA1c) before and after PG extract was supplied. RESULTS: The serum glucose, insulin, and HBA1c levels were significantly improved after the PG treatment compared to those found before PG treatment. In addition, Mg2+, lactate, and base deficit, and acidosis was significantly enhanced in treated rabbits. Moreover, PG showed hepato- and renoprotective effect. Likewise, electrolytes, lipid and protein profile were improved. CONCLUSION: The biochemical and hematological analysis data demonstrate that the PG is effective to alleviate the diabetes serious signs.

The cardiovascular depression caused by bee venom in Sprague-Dawley rats associated with a decrease of developed pressure in the left ventricular and the ratio of ionized calcium/ionized magnesium.

Bee venom (BV) has been used in Oriental medicine to treat inflammatory diseases, such as tendonitis, bursitis, and rheumatoid arthritis, despite the sensitivity of the victims and toxicity of the venom. This study examined the mechanisms for the effects of BV on the cardiovascular system in rats. The arterial pressure and heart rate (HR) were measured in anesthetized rats. In addition, the left ventricular development pressure (LVDP) and total magnesium efflux ([Mg]e) in isolated perfused hearts, the vascular tonic responses in the isolated aorta, and the blood ionic and biochemical changes were determined simultaneously. In the anesthetized rats, the mean arterial pressure, systolic pressure, and pulse pressure were reduced by BV in a dose-dependent manner, even though the HR was increased. BV had no effects on the relaxation of phenylephrine- or KCl-induced contraction of the aortic rings. In the isolated hearts, BV generated a reversible decrease in the LVDP and velocity with changes in pressure, which were accompanied by increases in the HR and [Mg]e. BV increased the plasma ionized and total magnesium concentrations, and decreased the total magnesium level in the red blood cells. The ratio of ionized calcium/ionized magnesium was also decreased by the BV treatment. BV caused a detectable increase in blood creatine kinase, glutamic oxaloacetic transaminase, and lactic dehydrogenase, as well as a decrease in the blood total protein albumin and globulin levels. These results suggest that BV induces cardiovascular depression by decreasing the cardiac pressure and increasing the ionized magnesium concentration in the blood.

Cucurbitacin I Protects H9c2 Cardiomyoblasts against H2O2-Induced Oxidative Stress via Protection of Mitochondrial Dysfunction.

Cucurbitacin I, a triterpenoid natural compound, exhibits various pharmacological properties, including anticancer, anti-inflammatory, and hepatoprotective properties. However, antioxidant effects of cucurbitacin I in cardiac cells are currently unknown. In the present study, we assessed the preventive effects of cucurbitacin I against the oxidative stress in H9c2 cardiomyoblasts. To evaluate antioxidant effects of cucurbitacin I in H9c2 cardiomyoblasts, H2O2-treated H9c2 cells were pretreated with various concentrations of the cucurbitacin I. Cell viability, reactive oxygen species (ROS) production, and apoptosis were determined to elucidate the protective effects of cucurbitacin I against H2O2-induced oxidative stress in H9c2 cells. In addition, we assessed the mitochondrial functions and protein expression levels of mitogen-activated protein kinases (MAPKs). Cucurbitacin I prevented the cells against cell death and ROS production and elevated the antioxidant protein levels upon oxidative stress. Furthermore, cucurbitacin I preserved the mitochondrial functions and inhibited the apoptotic responses in H2O2-treated cells. Cucurbitacin I also suppressed the activation of MAPK proteins (extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, and p38). Collectively, cucurbitacin I potentially protects the H9c2 cardiomyoblasts against oxidative stress and further suggests that it can be utilized as a therapeutic agent for the prevention of oxidative stress in cardiac injury.

Taurine increases cell proliferation and generates an increase in [Mg2+]i accompanied by ERK 1/2 activation in human osteoblast cells.

Taurine has been reported to influence bone metabolism, and its specific transport system, the taurine transporter, is expressed in osteoblasts. The mean [Mg2+]i was 0.51+/-0.01 mM in normal culture media. Taurine caused an increase in [Mg(2+)]i by 0.72+/-0.04 mM in human osteoblast (HOB) cells. This increment in [Mg2+]i was inhibited significantly by PD98059, nifedipine, lidocaine, and imipramine. Taurine was also shown to stimulate the activation of ERK 1/2. This taurine-stimulated ERK 1/2 activation was inhibited by PD98059. In the present study, taurine was shown to increase cell proliferation and generate an increase in [Mg2+]i accompanied by ERK 1/2 activation in HOB cells.

Reactive oxygen species regulate Bax translocation and mitochondrial transmembrane potential, a possible mechanism for enhanced TRAIL-induced apoptosis by CCCP.

TRAIL is a TNF family member that engages apoptosis via recruitment and rapid activation of caspase-8. Oxygen-free radicals, more generally known as reactive oxygen species (ROS) are well recognized for playing an important role in the regulation of tumor cell apoptosis. ROS within the cells act as secondary messengers in intracellular signalling cascades therefore function as anti-tumorigenic species. But very little is known about the effect of ROS on TRAIL-induced apoptosis. In this study we investigated the effect of CCCP, a classic uncoupler of oxidative phosphorylation, on TRAIL-induced apoptosis in TRAIL-resistant MCF-7 cells. It was found that pretreatment with CCCP for 6 h and then treatment with TRAIL for additional 3 h markedly enhanced apoptosis by 2-fold as compared with TRAIL alone. The uncoupling effect enhanced TRAIL-induced apoptosis by ROS generation. Moreover, CCCP treatment also reduced mitochondrial transmembrane potential (MTP, Delta Psi m) and induced Bax translocation to the mitochondria of its own account. This sensitization was inhibited with N-acetyl-L-cysteine (NAC) treatment by abrogating the ROS which was generated by the combined treatment of CCCP and TRAIL. Of interest, NAC also inhibited reduction of the Delta Psi m and Bax translocation after CCCP pretreatment which suggest that the generation of ROS may precede the loss in MTP. Thus, we demonstrated that CCCP-induced ROS generation enhanced TRAIL induced apoptosis by regulation of Bax translocation and mitochondrial transmembrane potential. The enhancing effect by CCCP-induced ROS generation was restored after NAC treatment. Therefore, our results suggest that uncoupling the cells by CCCP can overcome the resistance to TRAIL protein and can be a very efficient treatment for the tumor cells especially resistant to TRAIL-induced apoptosis.

Desipramine induces apoptosis in hepatocellular carcinoma cells.

Antitumor effects of antidepressants have been reported in many cancer cell lines. However, anti-proliferative effects of desipramine, a tricyclic antidepressant, in hepatocellular carcinoma are currently unknown. In this study, we examined the effects of desipramine in human hepatoma Hep3B cells. To evaluate anti-proliferative effects of desipramine in Hep3B cells, we determined cell viability, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), mitogen-activated protein kinase (MAPK) activity, and intracellular Ca2+ levels after desipramine treatment. Desipramine reduced cell viability, increased ROS production, and decreased MMP activity in Hep3B cells. In addition, desipramine activated MAPKs (ERK 1/2, JNK, and p38) and increased intracellular Ca2+ levels. Pro-apoptotic effects of desipramine were abolished after MAPK inhibitors (PD98059, SB203580, and SP600125) or N-acetyl-L-cysteine (NAC), as a ROS scavenger, treatments. These findings suggest that desipramine shows anti-proliferative effects in Hep3B cells mediated by promotion of apoptosis, activation of MAPK signaling, and increase in intracellular Ca2+ levels.

Alterations of Mg2+ After Hemorrhagic Shock.

Hemorrhagic shock is generally characterized by hemodynamic instability with cellular hypoxia and diminishing cellular function, resulting from an imbalance between systemic oxygen delivery and consumption and redistribution of fluid and electrolytes. Magnesium (Mg) is the fourth most abundant cation overall and second most abundant intracellular cation in the body and an essential cofactor for the energy production and cellular metabolism. Data for blood total Mg (tMg; free-ionized, protein-bound, and anion-bound forms) and free Mg2+ levels after a traumatic injury are inconsistent and only limited information is available on hemorrhagic effects on free Mg2+ as the physiologically active form. The aim of this study was to determine changes in blood Mg2+ and tMg after hemorrhage in rats identifying mechanism and origin of the changes in blood Mg2+. Hemorrhagic shock produced significant increases in blood Mg2+, plasma tMg, Na+, K+, Cl-, anion gap, partial pressures of oxygen, glucose, and blood urea nitrogen but significant decreases in RBC tMg, blood Ca2+, HCO3-, pH, partial pressures of carbon dioxide, hematocrit, hemoglobin, total cholesterol, and plasma/RBC ATP. During hemorrhagic shock, K+, anion gap, and BUN showed significant positive correlations with changes in blood Mg2+ level, while Ca2+, pH, and T-CHO correlated to Mg2+ in a negative manner. In conclusion, hemorrhagic shock induced an increase in both blood-free Mg2+ and tMg, resulted from Mg2+ efflux from metabolic damaged cell with acidosis and ATP depletion.

Nigella sativa seed extract attenuates the fatigue induced by exhaustive swimming in rats.

In previous studies, Nigella sativa (NS) has been studied due to its various physiological and pharmacological activities. However, evidence on the effects of NS on physical fatigue following exhaustive swimming remains limited. In the present study, the authors evaluated the potential beneficial effects of NS against the fatigue activity following exhaustive swimming. Rats were orally administered with NS extract (2 g/kg/day) for 21 days, and the anti-fatigue effect was assessed by exhaustive swimming exercise. The presented results indicated that pre-treatment of NS extract significantly increased the time to exhaustion. In hemodynamic parameters, NS extract increased blood pO2 and O2sat, but decreased pCO2. For underlying mechanisms, NS extract protected depletion of energy, indicated by increased levels of blood pH, glucose and tissue glycogen contents, and decreased levels of blood lactate, tissue lactic dehydrogenase and creatine kinase, when the NS extract was pre-treated. In addition, the NS extract inhibited oxidative stress following exhaustive swimming, as reflected by the results of increased levels of superoxide dismutase and redox ratio, and decreased the level of malondialdehyde when the NS extract was pre-treated. Collectively, the present study demonstrated that NS extract has an anti-fatigue activity against exhaustive swimming by energy restoration and oxidative-stress defense.

Hypocholesterolemic Effects of Probiotic Mixture on Diet-Induced Hypercholesterolemic Rats.

Growing evidence has indicated that supplementation with probiotics improves lipid metabolism. We aimed to investigate the beneficial effects of a probiotics mixture (PM) of three strains belonging to the species Bifidobacterium (B. longum, B. lactis, and B. breve) and two strains belonging to the species Lactobacillus (L. reuteri and L. plantarum) on cholesterol-lowering efficacy in hypercholesterolemic rats. A hypercholesterolemic rat model was established by feeding a high-cholesterol diet for eight weeks. To test the effects of PM on hypercholesterolemia, hypercholesterolemic rats were assigned to four groups, which were treated daily with low (1.65 × 108 cfu/kg), medium (5.5 × 108 cfu/kg), or high (1.65 × 1010 cfu/kg) doses of probiotic mixture or simvastatin for eight weeks. Significant reductions of serum total cholesterol (TC), triacylglycerol (TG), and low-density lipoprotein (LDL)-cholesterol levels, but increases of high-density lipoprotein (HDL)-cholesterol were observed after supplementation of PM in hypercholesterolemic rats. In PM-supplemented hypercholesterolemic rats, hepatic tissue contents of TC and TG also significantly decreased. Notably, the histological evaluation of liver tissues demonstrated that PM dramatically decreased lipid accumulation. For their underlying mechanisms, we demonstrated that PM reduced expressions of cholesterol synthesis-related proteins such as sterol regulatory element-binding protein 1 (SREBP1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) in the liver. Taken together, these findings suggest that PM has beneficial effects against hypercholesterolemia. Accordingly, our PM might be utilized as a novel therapeutic agent for the management of hypercholesterolemia.

pH-dependent modulation of intracellular free magnesium ions with ion-selective electrodes in papillary muscle of guinea pig.

A change in pH can alter the intracellular concentration of electrolytes such as intracellular Ca2+and Na2+ ([Na+]i) that are important for the cardiac function. For the determination of the role of pH in the cardiac magnesium homeostasis, the intracellular Mg2+ concentration ([Mg2+]i), membrane potential and contraction in the papillary muscle of guinea pigs using ion-selective electrodes changing extracellular pH ([pH]o) or intracellular pH ([pH]i) were measured in this study. A high CO2-induced low [pH]o causes a significant increase in the [Mg2+]i and [Na+]i, which was accompanied by a decrease in the membrane potential and twitch force. The high [pH]o had the opposite effect. These effects were reversible in both the beating and quiescent muscles. The low [pH]o-induced increase in [Mg2+]i occurred in the absence of [Mg2+]o. The [Mg2+]i was increased by the low [pH]i induced by propionate. The [Mg2+]i was increased by the low [pH]i induced by NH4Cl-prepulse and decreased by the recovery of [pH]i induced by the removal of NH4Cl. These results suggest that the pH can modulate [Mg2+]i with a reverse relationship in heart, probably by affecting the intracellular Mg2+ homeostasis, but not by Mg2+ transport across the sarcolemma.

Hepatoprotective effects of Nigella sativa seed extract against acetaminophen-induced oxidative stress.

OBJECTIVE: To investigate the protective effects of Nigella sativa seed extract (NSSE) against acetaminophen (APAP)-induced hepatotoxicity in TIB-73 cells and rats. METHODS: Toxicity in TIB-73 cells was induced with 10 µmol/L APAP and the protective effects of NSSE were evaluated at 25, 50, 75, 100 µg/mL. For in vivo examination, a total of 30 rats were equally divided into five experimental groups; normal control (vehicle), APAP (800 mg/kg body weight single IP injection) as a hepatotoxic control, and three APAP and NS pretreated (2 weeks) groups (APAP + NSSE 100 mg; APAP + NSSE 300 mg and APAP + NSSE 900 mg/kg). RESULTS: TIB-73 cell viability was drastically decreased by (49.0 ± 1.9)% after the 10 µmol/LAPAP treatment, which also increased reactive oxygen species production. Co-treatment with NSSE at 25, 50, 75, and 100 µg/mL significantly improved cell viability and suppressed reactive oxygen species generation. In vivo, the APAP induced alterations in blood lactate levels, pH, anionic gap, and ion levels (HCO3(-), Mg(2+) and K(+)), which tended to normalize with the NSSE pretreatment. The NSSE also significantly decreased elevated serum levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase induced by APAP, which correlated with decreased levels of hepatic lipid peroxidation (malondialdehyde), increased superoxide dismutase levels, and reduced glutathione concentrations. Improved hepatic histology was also found in the treatment groups other than APAP group. CONCLUSIONS: The in vitro and in vivo findings of this study demonstrated that the NSSE has protective effects against APAP-induced hepatotoxicity and metabolic disturbances by improving antioxidant activities and suppressing both lipid peroxidation and ROS generation.

Effects of candesartan, an angiotensin II receptor type I blocker, on atrial remodeling in spontaneously hypertensive rats.

Hypertension-induced structural remodeling of the left atrium (LA) has been suggested to involve the renin-angiotensin system. This study investigated whether treatment with an angiotensin receptor blocker, candesartan, regresses atrial remodeling in spontaneously hypertensive rats (SHR). Effects of treatment with candesartan were compared to treatment with a nonspecific vasodilatator, hydralazine. Thirty to 32-week-old adult male SHR were either untreated (n = 15) or received one of either candesartan cilexetil (n = 9; 3 mg/kg/day) or hydralazine (n = 10; 14 mg/kg/day) via their drinking water for 14 weeks prior to experiments. Untreated age- and sex-matched Wistar-Kyoto rats (WKY; n = 13) represented a normotensive control group. Untreated SHR were hypertensive, with left ventricular hypertrophy (LVH) compared to WKY, but there were no differences in systolic pressures in excised, perfused hearts. LA from SHR were hypertrophied and showed increased fibrosis compared to those from WKY, but there was no change in connexin-43 expression or phosphorylation. Treatment with candesartan reduced systolic tail artery pressures of conscious SHR below those of normotensive WKY and caused regression of both LVH and LA hypertrophy. Although hydralazine reduced SHR arterial pressures to those of WKY and led to regression of LA hypertrophy, it had no significant effect on LVH. Notably, LA fibrosis was unaffected by treatment with either agent. These data show that candesartan, at a dose sufficient to reduce blood pressure and LVH, did not cause regression of LA fibrosis in hypertensive rats. On the other hand, the data also suggest that normalization of arterial pressure can lead to the regression of LA hypertrophy.