Tristetraprolin activation by resveratrol inhibits the proliferation and metastasis of colorectal cancer cells.

Resveratrol (RSV) is a polyphenolic compound that naturally occurs in grapes, peanuts and berries. Considerable research has been conducted to determine the benefits of RSV against various human cancer types. Tristetraprolin (TTP) is an AU-rich element-binding protein that regulates mRNA stability and has decreased expression in human cancer. The present study investigated the biological effect of RSV on TTP gene regulation in colon cancer cells. RSV inhibited the proliferation and invasion/metastasis of HCT116 and SNU81 colon cancer cells. Furthermore, RSV induced a dose-dependent increase in TTP expression in HCT116 and SNU81 cells. The microarray experiment revealed that RSV significantly increased TTP expression by downregulating E2F transcription factor 1 (E2F1), a downstream target gene of TTP and regulated genes associated with inflammation, cell proliferation, cell death, angiogenesis and metastasis. Although TTP silencing inhibited TTP mRNA expression, the expression was subsequently restored by RSV. Small interfering RNA-induced TTP inhibition attenuated the effects of RSV on cell growth. In addition, RSV induced the mRNA-decaying activity of TTP and inhibited the relative luciferase activity of baculoviral IAP repeat containing 3 (cIAP2), large tumor suppressor kinase 2 (LATS2), E2F1, and lin­28 homolog A (Lin28) in HCT116 and SNU81 cells. Therefore, RSV enhanced the inhibitory activity of TTP in HCT116 and SNU81 cells by negatively regulating cIAP2, E2F1, LATS2, and Lin28 expression. In conclusion, RSV suppressed the proliferation and invasion/metastasis of colon cancer cells by activating TTP.

Arsenic trioxide induces growth inhibition and death in human pulmonary artery smooth muscle cells accompanied by mitochondrial O2•- increase and GSH depletion.

Arsenic trioxide (ATO; As2 O3 ) induces cell death in various cells via oxidative stress. Expose to chronic arsenic is involved in the development of vascular diseases. However, little is known about the cytotoxic effects of ATO on human normal vascular smooth muscle cells (VSMCs). Thus, in this study, we investigated the effects of ATO on cell growth and death in human pulmonary artery smooth muscle (HPASM) cells in relation to reactive oxygen species (ROS) and glutathione (GSH) levels. ATO treatment decreased the growth of HPASM cells with an IC50 of ∼30-50 µM at 24 h, and ATO induced HPASM cell death via apoptosis or necrosis dependent on the doses of it at this time. Treatment with 50 µM ATO did not increase ROS levels at the early time points, but it significantly increased mitochondrial O2•- levels at 24 h. ATO also induced GSH depletion in HPASM cells. N-acetyl cysteine (NAC; a well-known antioxidant) did not significantly affect apoptotic cell death, ROS levels, or GSH depletion in ATO-treated HPASM cells. However, l-buthionine sulfoximine (BSO; an inhibitor of GSH synthesis) intensified mitochondrial O2•- levels in ATO-treated HPASM cells, and significantly increased cell death and GSH depletion in these cells as well. In summary, we provided the first evidence that ATO inhibited the growth of HPASM cells, and induced apoptotic and/or necrotic cell death in these cells, accompanied by increases in mitochondrial O2•- level and GSH depletion.

Prospective investigation of change in the prostate-specific antigens after various urologic procedures.

PURPOSE: Prostate-specific antigen (PSA) is the most important marker in the diagnosis and follow-up of patients with prostate cancer. The primary objective of this study was to evaluate the effect of various urologic procedures in prostatic area on serum free and total PSA levels. SUBJECTS AND METHODS: A series of 62 patients (8 after digital rectal examination [DRE], 12 after transrectal ultrasonography [TRUS], 11 after rigid cystoscopy, 13 after prostatic massage, 8 after TRUS-guided prostate biopsy, and 10 after transurethral resection of prostate [TURP]) were enrolled in the study. Blood samples were taken from each patient before procedure and at 10, 30, 60, and 120 minutes after procedures. RESULTS: Prostate massage, rigid cystoscopy, TURP, and TRUS-guided prostate biopsy caused statistically significant rise in total and free PSA levels in the serum. There was no significant increase in total and free PSA levels in the serum after DRE and TRUS. The mean differences were greater for free PSA level in the serum for TURP, TRUS-guided prostate biopsy, prostate massage, and rigid cystoscopy. CONCLUSION: Total and free PSA levels in the serum are altered by prostate massage, rigid cystoscopy, TRUS-guided prostate biopsy, and TURP. The PSA rises were related to the stimulation strength of the procedures. The total and free PSA levels were increased significantly from 10 minutes after procedures, except DRE and TRUS, and were increased to maximal level at 60 minutes after procedures.

Characteristics of dendroaspis natriuretic peptide and its receptor in streptozotocin-induced diabetic rats.

Dendroaspis natriuretic peptide (DNP) shares a functionally important sequence homology with other natriuretic peptides. However, the characteristics of DNP and its receptor in the context of diabetes remafin to be fully elucidated. In the present study, alterations in the plasma levels and tissue contents of DNP and the properties of its receptor in diabetic rats, induced by streptozotocin (STZ) injection, were investigated. The plasma levels of DNP were 90.01 ± 4.12 and 196.68 ± 5.60 pg/ml in the control and STZ-induced diabetic rats, respectively. The tissue contents of DNP in the cardiac atrium, ventricle, renal cortex and inner medulla of the STZ-induced diabetic rats were also significantly increased compared with the control rats. Specific (125)I-DNP-binding sites were located predominantly in the glomeruli and inner medulla of the rat kidney. In the glomeruli of the kidney, the apparent dissociation constants (Kd) of (125)I-DNP in the control and STZ-induced diabetic rats were 0.41 ± 0.03 and 0.56 ± 0.06 nM, respectively. The maximum binding capacities (Bmax) of (125)I-DNP in control and STZ-induced diabetic rats were 2.98 ± 0.21 and 6.22 ± 1.06 fmol/mg protein, respectively. However, no differences were observed in the apparent Kd and Bmax of (125)I-DNP in the inner medulla of the kidney between the control and STZ-induced diabetic rats. In the glomerular and inner medullary kidney membranes, DNP stimulated the production of cyclic guanosine monophosphate (cGMP) in a dose-dependent manner. The magnitude of cGMP production in glomerular membranes was greater in the STZ-induced diabetic rats, whereas the magnitude of cGMP production in the inner medullary membranes was lower in the STZ-induced diabetic rats compared with the control rats. These results indicated that STZ-induced diabetes modulate DNP and its receptor, and also suggested that modulation of the DNP system is involved in the renal function of diabetic animals via the intracellular domain of the kidney NP receptor.

Relationships between blood Mg2+ and energy metabolites/enzymes after acute exhaustive swimming exercise in rats.

Magnesium (Mg) plays a central role in neuronal activity, cardiac excitability, neuromuscular transmission, muscular contraction, vasomotor tone, and blood pressure, all of which are significantly related to physical performance. To date, the available data about detection of blood total Mg (tMg; free-ionized, protein-bound, and anion-complex forms) are inconsistent, and there is limited information on blood free-ionized Mg (Mg(2+)) in relation to physical exercise. The aim of this study was to determine the biochemical changes related to energy metabolism after acute exhaustive swimming exercise (AESE) in rats in an attempt to correlate the role of blood Mg(2+) with metabolites/enzymes related to energy production. After AESE, blood Mg(2+), tMg, K(+), partial pressure of carbon dioxide, lactate, total protein (T-PRO), high-density lipoprotein (HDL), creatinine (CRE), blood urea nitrogen (BUN), uric acid (UA), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alanine phosphatase (ALP), lactate dehydrogenase (LDH), and creatinine kinase (CK) were significantly increased, whereas pH, partial pressure of oxygen, oxygen saturation, the Mg(2+)/tMg and Ca(2+)/Mg(2+) ratios, HCO3 (-), glucose, triglyceride (TG), and low-density lipoprotein (LDL) were significantly decreased. During AESE, lactate, T-PRO, albumin, AST, ALP, LDH, CK, CRE, BUN, and UA showed significant positive correlations with changes in blood Mg(2+), while glucose, TG, and LDL correlated to Mg(2+) in a negative manner. In conclusion, AESE induced increases in both blood Mg(2+) and tMg, accompanied by changes in blood metabolites and enzymes related to energy metabolism due to increased metabolic demands and mechanical damages.

Comparision of secretagogue effects of rosiglitazone and telmisartan on ANP secretion in rats.

Peroxisome proliferator-activated receptor-gamma (PPAR-γ), a nuclear transcription factor, is a key regulator of insulin signaling, and glucose and fat metabolism. In this study, we evaluated the direct effect of PPAR-γ ligand on the secretion of atrial natriuretic peptide (ANP). The isolated perfused beating atria were used and rosiglitazone (0.01, 0.3 and 1 µM) or telmisartan was perfused into atria with and without inhibitors. High frequency stimulation caused a decreased atrial contractility by 40% and an increased ANP secretion by 80%. Rosiglitazone augmented high frequency-induced ANP secretion and concentration in a dose-dependent manner. Rosiglitazone-induced ANP secretion was attenuated by the pretreatment with PPAR-γ antagonist (GW 9662), or inhibitor for phosphoinositol 3-kinase (PI3-kinase, wortmannin), Akt (API-2) or nitric oxide synthase (l-NAME). Telmisartan, a partial agonist of PPAR-γ with angiotensin II type 1 receptor (AT1R) blocker, also stimulated ANP secretion, which was more potent than rosiglitazone or losartan. Infusion of rosiglitazone or telmisartan in anesthetized rats tended to decrease mean arterial pressure and to increase pulse pressure without difference. A plasma ANP level was increased by telmisartan more than by rosiglitazone. In diabetic rats, an increased plasma ANP level was more prominent than sham rats. Therefore, we suggest that rosiglitazone stimulates high frequency-induced ANP secretion through the PPAR-γ receptor-PI3-kinase-Akt-eNOS pathway and telmisartan shows synergistic effect on ANP secretion.

Dendroaspis natriuretic peptide is degraded by a metalloproteinase in the rat kidney.

Our previous study demonstrated that the concentration of dendroaspis natriuretic peptide (DNP) was markedly higher than that of atrial NP (ANP) in rabbit plasma, indicating that DNP has a different metabolic rate from other NPs. Therefore, the metabolic characteristics of DNP in mammals require further analysis. The stabilities of NPs were determined by incubating 125I­labeled ANP, brain NP (BNP), C­type NP (CNP) and DNP at 37˚C for 1, 2 and 4 h, and analyzing their profiles by reversed­phase high­performance liquid chromatography. 125I­labeled ANP, BNP and CNP were quickly degraded in rat plasma, while 125I­labeled DNP was stable for 4 h. The relative stability of the peptides following incubation in rat plasma followed the rank order of: DNP>>>ANP≥BNP>>CNP. Organs were also examined for the degradation of DNP, including the spleen, kidney, liver, heart and lung. The physiological target organ for the degradation of DNP was observed to be the kidney. Furthermore, degradation of DNP in the kidney was attenuated by phenanthroline, a metalloproteinase inhibitor. Therefore, these results indicate that DNP has a longer stability in plasma and that it may have strong therapeutic applications in cardiac disease.

The ameliorative effects of L-2-oxothiazolidine-4-carboxylate on acetaminophen-induced hepatotoxicity in mice.

The aim of the study was to investigate the ameliorative effects and the mechanism of action of L-2-oxothiazolidine-4-carboxylate (OTC) on acetaminophen (APAP)-induced hepatotoxicity in mice. Mice were randomly divided into six groups: normal control group, APAP only treated group, APAP + 25 mg/kg OTC, APAP + 50 mg/kg OTC, APAP + 100 mg/kg OTC, and APAP + 100 mg/kg N-acetylcysteine (NAC) as a reference control group. OTC treatment significantly reduced serum alanine aminotransferase and aspartate aminotransferase levels in a dose dependent manner. OTC treatment was markedly increased glutathione (GSH) production and glutathione peroxidase (GSH-px) activity in a dose dependent manner. The contents of malondialdehyde and 4-hydroxynonenal in liver tissues were significantly decreased by administration of OTC and the inhibitory effect of OTC was similar to that of NAC. Moreover, OTC treatment on APAP-induced hepatotoxicity significantly reduced the formation of nitrotyrosin and terminal deoxynucleotidyl transferase dUTP nick end labeling positive areas of liver tissues in a dose dependent manner. Furthermore, the activity of caspase-3 in liver tissues was reduced by administration of OTC in a dose dependent manner. The ameliorative effects of OTC on APAP-induced liver damage in mice was similar to that of NAC. These results suggest that OTC has ameliorative effects on APAP-induced hepatotoxicity in mice through anti-oxidative stress and anti-apoptotic processes.

Antioxidant effect of astragalin isolated from the leaves of Morus alba L. against free radical-induced oxidative hemolysis of human red blood cells.

We evaluated the antioxidant properties of mulberry leaves extract (MLE) and flavonoids isolated from MLE. MLE was prepared by extraction with methanol. Flavonoids were analyzed by high-performance liquid chromatography. Oxidative hemolysis of normal human red blood cells (RBCs) was induced by the aqueous peroxyl radical [2,2'-Azobis (2-amidinopropane) dihydrochloride, AAPH]. MLE contained three flavonoids in the order quercetin (QC) > kaempferol (KF) > astragalin (AG). Oxidative hemolysis of RBCs induced by AAPH was suppressed by MLE, AG, KF, and QC in a time- and dose-dependent manner. MLE and these three flavonoids prevented the depletion of cystosolic antioxidant glutathione (GSH) in RBCs. AG had the greatest protective effect against AAPH-induced oxidative hemolysis and GSH depletion in RBCs.

Korean red ginseng and its primary ginsenosides inhibit ethanol-induced oxidative injury by suppression of the MAPK pathway in TIB-73 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Panax ginseng (P. ginseng) is one of the most widely used medicinal plants due to its wide spectrum of medicinal effects. Among the currently available Panax ginseng products, Korea red ginseng (KRG) has been shown to exhibit a variety of antioxidative and hepatoprotective action. AIM OF THE STUDY: Our aim was to investigate the effects of KRG and its primary ginsenosides (Rg3 and Rh2) on EtOH-induced injury to mouse hepatocytes (TIB-73). MATERIALS AND METHODS: We investigated the effects of KRG and its primary ginsenoside on EtOH-induced injury to TIB-73 cells and evaluated MAPKs signals as a possible mechanism of action. Hepatocytic injury was evaluated by biochemical assays as cell viability, lactate dehydrogenase (LDH), aspartate aminotransferase (AST), ROS and mitochondria membrane potential (MMP) level in TIB-73 cells. The levels of MAPK activation were analyzed by Western blots. RESULTS: The results showed that exposure of EtOH to TIB-73 cells led to cell death and membrane damage, accompanied by a decrease in cell viability, MMP, and Mg(2+) concentrations, but an increase in LDH, AST, ROS and MAPK activation. KRG and its primary ginsenosides reduced EtOH-induced generation of ROS and the activation of ERK and JNK, and increased Mg(2+) concentrations. CONCLUSION: These results suggest that KRG and its primary ginsenosides inhibit EtOH-induced oxidative injury by suppression of the MAPK pathway in TIB-73 cells.

Dendroaspis natriuretic peptide regulates the cardiac L-type Ca2+ channel activity by the phosphorylation of α1c proteins.

Dendroaspis natriuretic peptide (DNP), a new member of the natriuretic peptide family, is structurally similar to atrial, brain, and C-type natriuretic peptides. However, the effects of DNP on the cardiac function are poorly defined. In the present study, we examined the effect of DNP on the cardiac L-type Ca(2+) channels in rabbit ventricular myocytes. DNP inhibited the L-type Ca(2+) current (I(Ca,L)) in a concentration dependent manner with a IC(50) of 25.5 nM, which was blocked by an inhibitor of protein kinase G (PKG), KT5823 (1 µM). DNP did not affect the voltage dependence of activation and inactivation of I(Ca,L). The α(1c) subunit of cardiac L-type Ca(2+) channel proteins was phosphorylated by the treatment of DNP (1 µM), which was completely blocked by KT5823 (1 µM). Finally, DNP also caused the shortening of action potential duration in rabbit ventricular tissue by 22.3 ± 4.2% of the control (n = 6), which was completely blocked by KT5823 (1 µM). These results clearly indicate that DNP inhibits the L-type Ca(2+) channel activity by phosphorylating the Ca(2+) channel protein via PKG activation.

Renal actions of dendroaspis natriuretic peptide in rabbits.

Dendroaspis natriuretic peptide (DNP) is one of four members of the natriuretic peptide family sharing functional and structural properties. The purpose of the present study was to elucidate the physiological role of DNP on renal functions and its cellular mechanism in the rabbit kidney. DNP (5 µg/kg/min) infused intravenously increased urine volume and urinary excretion of electrolytes. These renal actions induced by DNP were more pronounced than those caused by atrial natriuretic peptide (ANP). We compared profiles of (125)I-ANP and (125)I-DNP by reverse-phase HPLC during incubation in rabbit plasma at 37°C for 1, 2, and 4h. While (125)I-ANP was quickly degraded within 1h, (125)I-DNP was still stable in plasma for 4h. DNP induced the greatest cyclic guanosine monophosphate (cGMP) production in the glomeruli in a dose-dependent manner, when compared to other renal structures including cortical tubules, outer medullary tubules, and inner medullary tubules. Affinity cross-linking analysis revealed NPR-A is selective receptor for DNP in glomeruli. Forskolin, a stimulator of adenylyl cyclase, significantly decreased cGMP production in the renal glomeruli but not in the renal medulla. In summary, DNP is a more effective activator of renal functions than ANP, possibly because of the degradation resistance of DNP against the endogenous peptidases in plasma or tissues. These findings suggest that DNP plays a pivotal role as a renal regulating peptide via specific natriuretic peptide receptors with a guanylyl cyclase domain.

Deciphering the role of paclitaxel in the SKGT4 human esophageal adenocarcinoma cell line.

Paclitaxel (taxol) has been used for the treatment of various human tumors and is an exceedingly efficient chemotherapy agent against esophageal cancer. However, the precise molecular mechanisms of paclitaxel effects on human esophageal adenocarcinoma cells are not well understood. MTT assay and cell cycle analysis were performed to examine the mechanism of antiproliferative and cell viability effects of paclitaxel in human esophageal adenocarcinoma cancer cells. Western blotting was also used to examine the cell cycle- and apoptosis-related proteins. Paclitaxel inhibited the proliferation of SKGT4 cells in a dose- and time-dependent manner with G2/M arrest. In addition, paclitaxel induced apoptosis through the activation of caspase-3 followed by PARP degradation. In conclusion, our results suggest that paclitaxel leads to mitotic cell cycle arrest following G2/M arrest and induces apoptosis via a caspase-3 pathway in SKGT4 cells.

Gallic acid-induced lung cancer cell death is accompanied by ROS increase and glutathione depletion.

Gallic acid (GA) is generally distributed in a variety of plants and foods, and its various biological effects have been reported. Here, we investigated the effects of GA and/or caspase inhibitors on Calu-6 and A549 lung cancer cells in relation to cell death and reactive oxygen species (ROS). The growths of Calu-6 and A549 cells were diminished with an IC(50) of approximately 30 and 150 µM GA at 24 h, respectively. GA also inhibited the growth of primary human pulmonary fibroblast (HPF) cells with an IC(50) of about 300 µM. GA induced apoptosis and/or necrosis in lung cancer cells, which was accompanied by the loss of mitochondrial membrane potential (MMP, ΔΨ(m)). The percents of MMP (ΔΨ(m)) loss and death cells by GA were lower in A549 cells than in Calu-6 cells. Caspase inhibitors did not significantly rescued lung cancer cells from GA-induced cell death. GA increased ROS levels including O(2) (•-) and induced GSH depletion in both lung cancer cells. Z-VAD (pan-caspase inhibitor) did not decrease ROS levels and GSH depleted cell number in GA-treated lung cancer cells. In conclusion, GA inhibited the growth of lung cancer and normal cells. GA-induced lung cancer cell death was accompanied by ROS increase and GSH depletion.

Taurine prevents hypertension and increases exercise capacity in rats with fructose-induced hypertension.

BACKGROUND: Fructose-induced hypertension was used to test the hypothesis that taurine supplementation and/or exercise can prevent hypertension and increase exercise capacity. METHODS: Five groups of 15 Sprague-Dawley rats were allocated and designated as control, high fructose-fed (fructose), high fructose-fed plus exercise (FE), high fructose-fed plus 2% taurine supplement (FT) and high fructose-fed plus 2% taurine supplement and exercise (FET) groups. Noninvasive systolic blood pressure (SBP) was recorded weekly and invasive arterial blood pressure (ABP) was recorded at the end of the 4-week trial. Three consecutive swimming tests were performed in the selected rats from each group and the plasma biomarkers were measured in the remaining rats. RESULTS: Noninvasive SBP differed significantly (P < 0.001) from week 3, both noninvasive and invasive ABP increased significantly (P < 0.001), and exercise capacity significantly decreased (P < 0.001) in the fructose group compared with the control group. The individual effects of swimming and taurine supplementation were incapable of preventing the development of hypertension and SBP significantly (P < 0.001) increased in the FE and FT groups; exercise capacity in those groups remained similar to control. The combined effects of exercise and taurine alleviated hypertension and significantly increased exercise capacity in the FET group. Insulin resistance increased significantly and plasma nitric oxide (NO) decreased significantly in the F, FE, and FT groups. Both parameters remained similar to control values in the FET group with an increasing antioxidant activity. CONCLUSION: Taurine supplementation in combination with exercise prevents hypertension and increases exercise capacity by possibly antioxidation and maintaining NO concentrations.

What is the role of unripe Rubus coreanus extract on penile erection?

The effect of unripe Rubus coreanus extract on rabbit penile corpus cavernosum (PCC) was evaluated. Penises were obtained from healthy male New Zealand white rabbits (2.5-3.0 kg). The pre-contracted penis with phenylephrine (Phe, 10 µM) was treated with various concentrations of an extract of unripe R. coreanus (0.5, 1, 2, 3 and 4 mg/mL). The change in penile tension was recorded, cyclic nucleotides in the perfusate and the PCC were measured by radioimmunoassay, and the expression of neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) in the perfused PCC were measured by western blotting. The interaction between unripe R. coreanus and sildenafil was also evaluated. The PCC relaxation induced by the extracts of R. coreanus was in a concentration-dependent manner and enhanced sildenafil-induced PCC relaxation. The perfusion of penile cavernous tissue with the unripe R. coreanus extract increased cGMP and cAMP in the tissue and in the perfusate and the expression of eNOS and nNOS in the tissue. The unripe R. coreanus extract exerts a relaxing effect on penile cavernous tissue in part by activating the NO-cGMP system and it may improve erectile dysfunction (ED), which does not completely respond to sildenafil citrate.

Presence of dendroaspis natriuretic peptide and its binding to NPR-A receptor in rabbit kidney.

Natriuretic peptides help to maintain sodium and fluid volume homeostasis in a healthy cardio-renal environment. Since the identification of Dendroaspis natriuretic peptide (DNP) as a new member of the natriuretic peptide family, DNP has been considered as an important regulator of natriuresis and dieresis. The present study was undertaken to investigate the presence of immunoreactive Dendroaspis natriuretic peptide (DNP) and its specific receptor in rabbit. DNP was detected in heart, kidney, liver, brain, and plasma by radioimmunoassay (RIA). DNP contents of cardiac atrium and ventricle, renal cortex and medulla, liver, and brain were 1.42 ± 0.15, 1.0 6 ± 0.08, 2.55 ± 0.21, 1.81 ± 0.16, 1.36 ± 0.22, and 0.69 ± 0.15 pg/mg of wet weight, respectively. The concentration of DNP in plasma was 235.44 ± 15.44 pg/ml. By quantitative in vitro receptor autoradiography, specific ¹²5I-DNP binding sites were revealed in glomeruli, interlobular artery, acuate artery, vasa recta bundle, and inner medulla of the kidney with an apparent dissociation constant (K(d)) of 0.29 ± 0.05, 0.36 ± 0.03, 0.84 ± 0.19, 1.18 ± 0.23, and 10.91 ± 1.59 nM, respectively. Basal rate of 3', 5'-cyclic guanosine monophosphate (cGMP) production by particulate guanylyl cyclase (GC) activation of glomerular membranes was basally 13.40 ± 1.70 pmol/mg protein/min. DNP caused an increment of cGMP production in similar magnitude to that caused by ANP, BNP, and urodilatin, while the production of cGMP by CNP was significantly lower than that by DNP. Our results show that plasma levels of DNP were higher when compared to other tissues. DNP produces cGMP via the NPR-A receptor subtype in the kidney, similarly to ANP and BNP, suggesting that plasma DNP could have similar functions as ANP and BNP.

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.

Attenuation of MG132-induced HeLa cell death by N-acetyl cysteine via reducing reactive oxygen species and preventing glutathione depletion.

MG132 as a proteasome inhibitor can induce apoptotic cell death through formation of reactive oxygen species (ROS). In this study, the effects of N-acetyl cysteine (NAC; an antioxidant) on MG132-induced HeLa cell death in relation to ROS and glutathione (GSH) were investigated. MG132 induced cell growth inhibition and apoptosis in HeLa cells, which was accompanied by the loss of mitochondrial membrane potential (MMP; Delta Psi(m)), activation of caspase-3 and poly (ADP-ribose) polymerase (PARP) cleavage. MG132 increased ROS levels, including O(2)(*-), and GSH depleted cell numbers of HeLa cells. NAC reduced the number of annexin V-positive cells and MMP (Delta Psi(m)) loss by MG132. In addition, NAC significantly reduced the ROS level and prevented GSH depletion. In conclusion, NAC prevented MG132-induced HeLa cell death via decreasing ROS and preventing GSH depletion.

Treatment with p38 inhibitor intensifies the death of MG132-treated As4.1 juxtaglomerular cells via the enhancement of GSH depletion.

MG132, as a proteasome inhibitor, has been shown to induce apoptotic cell death through the formation of reactive oxygen species (ROS). In this study, we investigated the effects of MG132 and/or MAPK inhibitors on As4.1 juxtaglomerular cells in relation to cell growth, cell death, ROS, and glutathione (GSH) levels. MG132 inhibited the growth of As4.1 cells and induced cell death, accompanied by the loss of mitochondrial membrane potential (MMP; DeltaPsi(m)) and activation of caspase-3 and -8. MG132 increased ROS levels, and GSH depleted cell numbers. The MEK inhibitor slightly reduced cell growth and caspase-3 activity in MG132-treated As4.1 cells and mildly increased MMP (DeltaPsi(m)) loss and O(2)(*-) level. However, it did not increase apoptosis and GSH depletion. The JNK inhibitor did not strongly influence cell growth, cell death, and GSH depletion by MG132, but increased caspase-3 activity, MMP (DeltaPsi(m)) loss, and O(2)(*-) level. Treatment with the p38 inhibitor magnified cell-growth inhibition and apoptosis by MG132. This agent also strongly increased caspase-8 activity, MMP (DeltaPsi(m)) loss, O(2)(*-) level, and GSH depletion. Conclusively, the p38 inhibitor strongly intensified cell death in MG132-treated As4.1 cells. The changes of GSH content by MG132 and/or MAPK inhibitors were closely related to the death of As4.1 cells.