Progress in endosomal Na⁺,K⁺/H⁺ antiporter in Arabidopsis thaliana / 生物工程学报

Important progress has been made in the interpretation of subcellular location, ion transport characteristics and biological functions of endosomal Na⁺,K⁺/H⁺ antiporter in Arabidopsis thaliana. The endosomal Na⁺,K⁺/H⁺ antiporter contain two members, AtNHX5 and AtNHX6, whose amino acid sequence similarity is 78.7%. Studies have shown that AtNHX5 and AtNHX6 are functionally redundant, and they are all located in Golgi, trans-Golgi network (TGN), endoplasmic reticulum (ER) and prevacuolar compartment (PVC). AtNHX5 and AtNHX6 are critical for salt tolerance stress and the homeostasis of pH and K⁺. It has been reported that there are conservative acidic amino acid residues that can regulate their ion activity in the endosomal NHXs transmembrane domain, which plays a decisive role in their own functions. The results of the latest research indicate that endosomal NHXs affect vacuolar transport and protein storage, and participate in the growth of auxin-mediated development in A. thaliana. In this paper, the progress of subcellular localization, ion transport, function and application of endosomal NHXs in A. thaliana was summarized.

A Novel Polyclonal Antiserum against Toxoplasma gondii Sodium Hydrogen Exchanger 1

The sodium hydrogen exchanger 1 (NHE1), which functions in maintaining the ratio of Na+ and H+ ions, is widely distributed in cell plasma membranes. It plays a prominent role in pH balancing, cell proliferation, differentiation, adhesion, and migration. However, its exact subcellular location and biological functions in Toxoplasma gondii are largely unclear. In this study, we cloned the C-terminal sequence of T. gondii NHE1 (TgNHE1) incorporating the C-terminal peptide of NHE1 (C-NHE1) into the pGEX4T-1 expression plasmid. The peptide sequence was predicted to have good antigenicity based on the information obtained from an immune epitope database. After induction of heterologous gene expression with isopropyl-b-D-thiogalactoside, the recombinant C-NHE1 protein successfully expressed in a soluble form was purified by glutathione sepharose beads as an immunogen for production of a rabbit polyclonal antiserum. The specificity of this antiserum was confirmed by western blotting and immunofluorescence. The antiserum could reduce T. gondii invasion into host cells, indicated by the decreased TgNHE1 expression in T. gondii parasites that were pre-incubated with antiserum in the process of cell entry. Furthermore, the antiserum reduced the virulence of T. gondii parasites to host cells in vitro, possibly by blocking the release of Ca2+. In this regard, this antiserum has potential to be a valuable tool for further studies of TgNHE1.

Oxidative Stress-Activated NHE1 Is Involved in High Glucose-Induced Apoptosis in Renal Tubular Epithelial Cells

PURPOSE: Diabetic nephropathy (DN) is a prevalent chronic microvascular complication of diabetes mellitus involving disturbances in electrolytes and the acid-base balance caused by a disorder of glucose metabolism. NHE1 is a Na+/H+ exchanger responsible for keeping intracellular pH (pHi) balance and cell growth. Our study aimed to investigate roles of NHE1 in high glucose (HG)-induced apoptosis in renal tubular epithelial cells. MATERIALS AND METHODS: Renal epithelial tubular cell line HK-2 was cultured in medium containing 5 mM or 30 mM glucose. Then, cell apoptosis, oxidative stress, NHE1 expression, and pHi were evaluated. NHE1 siRNA and inhibitor were used to evaluate its role in cell apoptosis. RESULTS: HG significantly increased cell apoptosis and the production of reactive oxygen species (ROS) and 8-OHdG (p<0.05). Meanwhile, we found that HG induced the expression of NHE1 and increased the pHi from 7.0 to 7.6 after 48 h of incubation. However, inhibiting NHE1 using its specific siRNA or antagonist DMA markedly reduced cell apoptosis stimulated by HG. In addition, suppressing cellular oxidative stress using antioxidants, such as glutathione and N-acetyl cysteine, significantly reduced the production of ROS, accompanied by a decrease in NHE1. We also found that activated cyclic GMP-Dependent Protein Kinase Type I (PKG) signaling promoted the production of ROS, which contributed to the regulation of NHE1 functions. CONCLUSION: Our study indicated that HG activates PKG signaling and elevates the production of ROS, which was responsible for the induction of NHE1 expression and dysfunction, as well as subsequent cell apoptosis, in renal tubular epithelial cells.

A atividade do NHE3 em túbulo proximal é inibida pela sinalização enviesada do receptor de angiotensina II tipo 1/beta-arrestina / Proximal tubule NHE3 activity is inhibited by beta-arrestin-biased angiotensin II type 1 receptor signaling

Os receptores medeiam a maioria das respostas fisiológicas em resposta a diversidade de estímulos. A ativação da sinalização mediada pelo receptor de angiotensina II tipo 1 é o principal responsável pelos efeitos do hormônio angiotensina II (Ang II) nos tecidos alvo. No rim concentrações fisiológicas de Ang II aumentam a atividade no túbulo proximal da isoforma 3 do trocador de Na+/H+ (NHE3). Este efeito é crucial para a manutenção do volume extracelular e pressão arterial. Evidências recentes mostraram que a ativação seletiva da sinalização enviesada da beta-arrestina/ receptor AT1 induz diurese e natriurese independentemente da sinalização via proteína G. Neste estudo testamos a hipótese de que a sinalização enviesada do receptor AT1/ beta-arrestina inibe a atividade do NHE3 no túbulo proximal, bem como investigar os possíveis mecanismos moleculares que medeio este efeito. Para tal, nós determinamos os efeitos do composto TRV120023, que se liga ao receptor AT1, bloqueando o acoplamento da proteína G e estimulando a sinalização da beta-arrestina, na função do NHE3 in vivo e in vitro. A atividade do NHE3 foi medida quer em túbulo proximal nativo, por meio de microperfusão estacionária, bem como em uma linha celular de túbulo proximal de gamba (OKP), por meio de recuperação de pH intracelular dependente de Na+. Os nossos resultados mostram que o TRV120023 na concentração de 10-7 M inibe marcadamente a atividade do NHE3 em túbulo proximal quer in vivo quer in vitro, sendo que este efeito é completamente abolido nas células silenciadas para a beta-arrestina 1 e 2 através de RNA de interferência. Adicionalmente, a estimulação do NHE3 pela Ang II é completamente suprimida pelo TRV120023 quer in vivo quer in vitro. A inibição do NHE3 pelo TRV120023 foi associada com a diminuição do NHE3 expresso na superfície da membrana plasmática em células OKP e com a redistribuição entre o corpo e a base das microvilosidades em túbulo proximal de rato. A...

Cell surface receptors mediate most of our physiological responses to an array of stimulus. The triggering of the angiotensin II type I (AT1) receptor signaling is the major control point in the regulation of the ultimate effects of the peptide hormone angiotensin II (Ang II) on its target tissue. In the kidney physiological concentrations of Ang II upregulate the activity of proximal tubule Na+/H+ exchanger isoform 3 (NHE3). This effect is crucial for maintenance of extracellular fluid volume homeostasis and blood pressure. Recent findings have shown that selective activation of the betaarrestin-biased AT1 receptor signalingpathway induces diuresis and natriuresis independent of G-protein mediated signaling. This study tested the hypothesis that activation of this AT1 receptor/beta-arrestin signaling inhibits NHE3 activity in proximal tubule as well as investigate the underlying molecular mechanisms mediating this effect. To this end, we determined the effects of the compound TRV120023, which binds to the AT1R, blocks G protein coupling, and stimulates beta-arrestin signaling, on NHE3 function in vivo and in vitro. NHE3 activity was measured in both native proximal tubules, by stationary microperfusion, and in opossum proximal tubule (OKP) cells, by Na+-dependent intracellular pH recovery. Our results showed that 10-7 MTRV120023 remarkably inhibited proximal tubule NHE3 activity both in vivo and in vitro, and the effect was completely abolished in OKP cells silenced for beta-arrestin 1 and 2 by small interference RNA. Additionally, stimulation of NHE3 by Ang II was completely suppressed by TRV120023 both in vivo as well as in vitro. Inhibition of NHE3 activity by TRV120023 was associated with a decrease in NHE3 surface expression in OKP cells and with a redistribution from the body to the base of the microvilli in the rat proximal tubule. The decreased surface NHE3 in OKP cells was associated with an increase in NHE3 internalization via...

Incorporation of Na+/H+ antiporter gene from Aeluropus littoralis confers salt tolerance in soybean (Glycine max L.).

To develop a salt-tolerant soybean (Glycine max L.) cultivar, a minimal linear Na+/H+ antiporter gene cassette (35S CaMV promoter, open-reading-frame of AlNHX1 from Aeluropus littoralis and NOS terminator) was successfully expressed in soybean cultivar TF-29. Southern and Northern blot analysis showed that AlNHX1 was successfully incorporated into the genome and expressed in the transgenic plants. The AlNHX1 transgenic plant lines exhibited improved growth in severe saline condition (150 mM NaCl). The transgenic lines accumulated a lower level of Na+ and a higher level of K+ in the leaves than wild-type plants under saline condition (150 mM NaCl). Observations on the chlorophyll content, photosynthetic rates, malondialdehyde and relative electrical conductivity indicated that transgenic plants exhibited tolerance to salt stress, growing normally at salt concentrations up to 150 mM. These results demonstrated that AlNHX1 was successfully transferred into soybean and the salt-tolerance was improved by the overexpression of AlNHX1.

Alkali Therapy Attenuates the Progression of Kidney Injury via Na/H Exchanger Inhibition in 5/6 Nephrectomized Rats

Metabolic acidosis is a cause of renal disease progression, and alkali therapy ameliorates its progression. However, there are few reports on the role of renal acid-base transporters during alkali therapy. We evaluated the effect of sodium bicarbonate therapy and the role of acid-base transporters on renal disease progression in rats with a remnant kidney. Sprague-Dawley rats consumed dietary sodium bicarbonate (NaHCO3) or sodium chloride (NaCl) with 20% casein after a 5/6 nephrectomy. After being provided with a casein diet, the NaHCO3-treated group had higher levels of serum bicarbonate than the control group. At week 4, the glomerular filtration rate in the NaHCO3 group was higher than that in the NaCl group, and the difference became prominent at week 10. The glomerulosclerosis and tubulointerstitial damage indices in the NaHCO3 group were less severe compared with controls at week 4 and 10. The expression of the Na/H exchanger (NHE) was decreased, and apical reactivity was decreased in the NaHCO3 group, compared with the NaCl group. Endothelin-1 levels in the kidney were also decreased in the NaHCO3 group. Dietary sodium bicarbonate has the effects of ameliorating renal disease progression, which may be related to the altered expression of NHE in the remaining kidney.

Inhibition of central Na(+)/H(+) exchanger type 3 can alleviate sleep apnea in Sprague-Dawley rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Recent studies showed the central Na+/H+ exchanger type 3 (NHE3) has a close relationship with ventilation control. The objective of the study is to investigate the role of NHE3 in sleep apnea in Sprague-Dawley (SD) rats.</p><p><b>METHODS</b>A sleep study was performed on 20 male SD rats to analyze the correlation between the sleep apneic events and total NHE3 protein content and inactive NHE3(pS552) in the brainstem measured by Western blotting. Another 20 adult male SD rats received 3 days of sleep and respiration monitoring for 6 hours a day, with adaption on the first day, 0.5% DMSO microinjection into the fourth ventricle on the second day, and AVE0657 (specific inhibitor of NHE3) microinjection on the third day. Rats were divided into two groups with injection of 5 µmol/L or 8 µmol/L AVE0657 before the sleep study. The effects of AVE0657 on sleep apnea and sleep structure of rats were analyzed through self-control.</p><p><b>RESULTS</b>The total post-sigh apnea index (TPSAI) and post-sigh apnea index in non-rapid eye movement (NREM) sleep (NPSAI) and total apnea index (AI) in NREM sleep (NAI) were negatively correlated with NHE3(pS552) protein contents in the brainstem (r = -0.534, -0.547 and -0.505, respectively, P < 0.05). The spontaneous apnea index in REM sleep (RSPAI) was positively correlated with the level of NHE3(pS552) protein expression in the brainstem (r = 0.556, P < 0.05). However, the sleep AI had no relationship with total NHE3 protein. Compared with the blank control and microinjection of 0.5% DMSO, 5 µmol/L AVE0657 significantly reduced the total AI and NPSAI (both P < 0.05) without a significant effect on sleep architecture. In contrast to blank control and microinjection of 0.5% DMSO, injection of 8 µmol/L AVE0657 significantly reduced the AI and PSAI in NREM and REM sleep (all P < 0.05).</p><p><b>CONCLUSIONS</b>The severity of sleep apnea was negatively correlated with central inactive NHE3. A specific inhibitor of NHE3 decreased the sleep AI. Thus, our results indicate that central NHE3 might be a molecular target for sleep apnea treatment, whose inhibitors may be potential therapeutic drugs for sleep apnea.</p>

Bicarbonate reabsorption in proximal renal tubule: molecular mechanisms and metabolic acidosis / 生理学报

HCO3(-) reabsorption in the renal tubules plays a critically important role in maintaining the global acid-base balance. Loss of HCO3(-) causes metabolic acidosis. Proximal renal tubule is the major site for HCO3(-) reabsorption, accounting for more than 80% of total HCO3(-) reabsorption along the nephron. Over the past more than half centuries, tremendous progresses have been made on understanding the molecular mechanisms underlying the HCO3(-) reabsorption in proximal tubules. The transepithelial movement of HCO3(-) involves the coordinated operation of machineries on both the apical and the basolateral membranes of the epithelial cells. On the apical domain, Na(+)-H(+) exchanger NHE3 and the vacuolar H(+)-ATPase are two major pathways mediating the apical uptake of HCO3(-)-related species. Taken together, NHE3 and H(+)-ATPase are responsible for about 80% of HCO3(-) reabsorption in the proximal tubule. The remaining 20% is likely mediated by pathways yet to be characterized. On the basolateral membrane, NBCe1 represents the only major known pathway mediating the extrusion of HCO3(-) coupled with Na(+) into the interstitial space. In the present article, we provide a historical view about the studies on the mechanisms of HCO3(-) reabsorption since 1940s. Moreover, we summarize the latest progresses emerging over the past decade in the physiological as well as pathological roles of acid-base transporters underlying the HCO3(-) reabsorption in proximal tubules.

Inhibition of NHE1 down-regulates IL-8 expression and enhances p38 phosphorylation / 中国实验血液学杂志

This study was purposed to explore the changes of possible angiogenetic factors other than VEGF after inhibition of NHE1 and their related mechanisms. The K562 cells were treated by NHE1 specific inhibitor cariporide, the angiogenesis factors after inhibition of NHE1 were screened by using protein chip, the IL-8 expression level after cariporide treatment was detected by real-time quantitative PCR; the K562 cells with stable interference of NHE1 were constructed, the IL-8 expression level after interference of NHE1 was detected by real-time quantitative PCR; the p38 phosphorylation level in K562 cells treated with cariporide was detected by Western blot. After treatment of K562 cells with p38 inhibitor SB203580, the IL-8 expression level was decreased by real-time quantitative PCR. The results of protein chip showed that IL-8 expression decreased after cariporide treatment. Real-time quantitative PCR confirmed this inhibitory effect. The p38 phosphorylation level increased after cariporide treatment. The down-regulation of IL-8 expression induced by cariporide treatment was partially restored after K562 cells were treated with p38 inhibitor SB203580. It is concluded that the inhibition of NHE1 can inhibit IL-8 expression through up-regulation of p38 phosphorylation.

The relationship of virus load, receptor expression and tumor spectrum in layer chickens infected by ALV-J / 病毒学报

Abstract:Subgroup J avian leukosis virus (ALV-J) infect cells by binding to the chNHE1 receptor protein of the host and causes tumors. The tumor incidence of the ALV-J-infected chickens was observed by histo pathology, and virus was isolated on DF-1 cell line. The ALV-J load and mRNA of chNHElreceptor protein were detected by real time PCR. The relationship between ALV-J load, chNHE1 receptor expression levels and tumor spectrum was analyzed. The results showed that the tumors induced by ALV-J in laying hens and local lines of chicken were different. No significant relationship was observed between ALV-J load and tumor spectrum. ALV-J load was positively correlated with mRNA expression of chNHE1. The mRNA expression of chNHE1 increased when the tumors occurred. Our results suggest the chNHE1 protein is not only the receptor of ALV-J infected host but also play an important role in the process of tumor development. This study provides a scientific basis for further studying of oncogenic mechanism of ALV-J.

Increasing sensitivity of leukemia cells to imatinib by inhibiting NHE1 and p38MAPK signaling pathway / 中国实验血液学杂志

This study was aimed to investigate whether the inhibition of NHE1 activity and intracellular acidification can reverse resistance of leukemia cells to the imatinib and to explore downstream signal molecule networks of BCR/ABL in the cells of chronic myelocytic leukemia (CML) patients. The mRNA and protein expression of P-glycoprotein (Pgp) and the drug accumulation were assayed after acidifying the primary leukemia cells of patients or K562/DOX and K562/G01 cells. The effects of intracellular acidification of primary leukemia cells on the phosphorylation level changes of ERK1/2 and p38 MAPK were analyzed by Western blot. The results showed that the intracellular concentration of drugs in the advanced patients increased and the sensitivity of K562/DOX and K562/G01 cells to imatinib was enhanced after intracellular acidification or treatment with NHE1 inhibitor cariporide. With downregulation of intracellular pH, the phosphorylation of p38 MAPK decreased in advanced patients and the phosphorylation of ERK1/2 increased within 3 min and then decreased after 30 min. SB203580, the specific inhibitor of p38 MAPK, displayed a synergistic effect with the inhibitor of NHE1 to downregulate the mRNA and protein expression of Pgp. It is concluded that the inhibiton of NHE1 can significantly decrease the protein expression of Pgp in K562/DOX and K562/G01 cells, increase the accumulation of Rhodamine123 and doxorubicin in the cells of advanced patients and enhance the sensitivity of cells to imatinib in which the p38 MAPK signal transduction pathways involves.

Adenosine alleviates hypoxia-induced rat right ventricular hypertrophy through the NHE-1/CaN signal pathway / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of adenosine and its agonist on hypoxia-induced right ventricular hypertrophy (RVH) and explore the underlying mechanism.</p><p><b>METHODS</b>Fifty-six rats were randomly divided into normoxia group, hypoxia group, and treated hypoxia groups (with different treatments with adenosine, A1 receptor agonist CPA, A2 receptor agonist NECA, CPA plus A1 receptor inhibitor DPCPX, or NECA plus A2B receptor inhibitor MRS1754). The rats except for those in normoxia group were exposed to normobaric chronic hypoxia (9.5%-10.5% oxygen) for 21 days, and the corresponding treatments were administered since the 7th day of hypoxia till day 21 via implantable capsule with a pressure pump. After the treatments, the right ventricles were then removed and weighed for evaluation of hypertrophy, and the expressions of NHE-1 and CnAβ mRNA in the myocardial tissue were detected using RT-PCR.</p><p><b>RESULTS</b>After a 21-day hypoxia, the rats showed significantly increased RV/(LV+S) ratio (0.369∓0.033) and RV/BW ratio (0.75∓0.095) compared to those in normoxia group (0.271∓0.010 and 0.59∓0.039, respectively; P<0.001), adenosine treatment group (0.281∓0.022 and 0.65∓0.077, respectively; P<0.001, P=0.025), hypoxia with CPA group (0.313∓0.021 and 0.66∓0.067, respectively P<0.001), and hypoxia with NECA group(0.333∓0.019, and 0.68∓0.074, respectively P<0.001). The NHE-1 and CnAβ mRNA levels in hypoxia group were significantly higher than those in normoxia group, adenosine treatment group, hypoxia with CPA group, and hypoxia with NECA group(P<0.001).</p><p><b>CONCLUSION</b>Adenosine and its agonist can inhibit hypoxia-induced RVH in rats through the NHE-1/CaN signal pathway.</p>

Altered Regulation of Renal Acid Base Transporters in Response to Ammonium Chloride Loading in Rats

The role of the kidney in combating metabolic acidosis has been a subject of considerable interest for many years. The present study was aimed to determine whether there is an altered regulation of renal acid base transporters in acute and chronic acid loading. Male Sprague-Dawley rats were used. Metabolic acidosis was induced by administration of NH4Cl for 2 days (acute) and for 7days (chronic). The serum and urinary pH and bicarbonate were measured. The protein expression of renal acid base transporters [type 3 Na+/H+ exchanger (NHE3), type 1 Na+/HCO3- cotransporter (NBC1), Na-K+ ATPase, H(+)-ATPase, anion exchanger-1 (AE-1)] was measured by semiquantitative immunoblotting. Serum bicarbonate and pH were decreased in acute acid loading rats compared with controls. Accordingly, urinary pH decreased. The protein expression of NHE3, H(+)-ATPase, AE-1 and NBC1 was not changed. In chronic acid loading rats, serum bicarbonate and pH were not changed, while urinary pH was decreased compared with controls. The protein expression of NHE3, H(+)-ATPase was increased in the renal cortex of chronic acid loading rats. These results suggest that unaltered expression of acid transporters combined with acute acid loading may contribute to the development of acidosis. The subsequent increased expression of NHE3, H(+)-ATPase in the kidney may play a role in promoting acid excretion in the later stage of acid loading, which counteract the development of metabolic acidosis.

Essential regulatory elements for NHE3 gene transcription in renal proximal tubule cells

The objectives of the present study were to identify the cis-elements of the promoter absolutely required for the efficient rat NHE3 gene transcription and to locate positive and negative regulatory elements in the 5’-flanking sequence (5’FS), which might modulate the gene expression in proximal tubules, and to compare this result to those reported for intestinal cell lines. We analyzed the promoter activity of different 5’FS segments of the rat NHE3 gene, in the OKP renal proximal tubule cell line by measuring the activity of the reporter gene luciferase. Because the segment spanning the first 157 bp of 5’FS was the most active it was studied in more detail by sequential deletions, point mutations, and gel shift assays. The essential elements for gene transcription are in the region -85 to -33, where we can identify consensual binding sites for Sp1 and EGR-1, which are relevant to NHE3 gene basal transcription. Although a low level of transcription is still possible when the first 25 bp of the 5’FS are used as promoter, efficient transcription only occurs with 44 bp of 5’FS. There are negative regulatory elements in the segments spanning -1196 to -889 and -467 to -152, and positive enhancers between -889 and -479 bp of 5’FS. Transcription factors in the OKP cell nuclear extract efficiently bound to DNA elements of rat NHE3 promoter as demonstrated by gel shift assays, suggesting a high level of similarity between transcription factors of both species, including Sp1 and EGR-1.

Inhibition of NHE1 promotes hypoxia-induced differentiation of K562 leukemic cells / 中国实验血液学杂志

This study was purposed to investigate the effect of hypoxia microenvironment on K562 leukemic cell differentiation, and characteristics of NHE1 involvement in this process. The K562 cells were treated with hypoxia-mimical agent CoCl₂ or under actual hypoxia culture, and the specific NHE1 inhibitor Cariporide was used to inhibit NHE1 activity. The fluorescent probe BCECF was used for pH(i) measurements. Gene expression was analyzed by RT-PCR. The morphological characteristics was determined by Wright's staining. Signaling pathways were detected by Western blot using phosphospecific antibodies. The results indicated that the hypoxia or mimetic hypoxia favored K562 cells differentiation with up-regulation of C/EBPα. Moreover, treatment with Cariporide under hypoxia synergistically enhanced leukemia cell differentiation. Treatment with Cariporide increased levels of phosphorylated ERK5 and P38 mitogen-activated protein kinase (MAPK). It is concluded that the hypoxia or mimetic hypoxia can induce the differentiation of K562 cells, the inhibition of NHE1 activity can promote the hypoxia-induced K562 cell differentiation. The enhancement of hypoxia-induced K562 differentiation by Cariporide via MAPK signal pathway suggests a possible therapeutic target of NHE1 under hypoxia microenvironment in the treatment of leukemias.

Na(+)/H(+) exchanger 1 expression and its effect on apoptosis in K562 and HL-60 cells with DNA damage / 中国实验血液学杂志

This study was aimed to investigate the expression of Na(+)/H(+) exchanger 1 (NHE1) in K562 and HL-60 cells undergoing DNA damage induced by etoposide and to elucidate the regulating mechanism. Real-time quantitative PCR (RQ-PCR) and Western blot methods were used to determine the expression of NHE1 in K562 cells after the treating with etoposide. Meanwhile, the flow cytometry was used to detect the apoptosis of leukemic cells. The luciferase reporter vector containing NHE1 promoter was constructed to measure relative luciferase activity after treating with different etoposide concentrations. The results showed that the mRNA and protein of NHE1 increased in accordance with apoptosis ratio in HL-60 cells after treated with etoposide (p < 0.05), but no such obvious increase in K562 cells. Treatment with NHE1 specific inhibitor could block etoposide induced alkalization and reduce the apoptosis ratio of HL-60 cells. The expression pattern and apoptosis alteration was not similar in K562 cells. Relative luciferase activity of reporter vector containing NHE1 promoter however increased in K562 cells after treated with etoposide. It is concluded that the expression of NHE1 is up-regulated in the process of apoptosis of HL-60 cells induced by etoposide and depends on the pHi increasing caused by NHE1 up-regulation which is not found in K562 cells although the transcriptional activity increased.

Design, synthesis and Na+/H+ exchanger isoform-1 inhibitory activity of feruloylagmatine analogues / 药学学报

In order to search for novel inhibitors of Na+/H+ exchanger isoform-1 (NHE-1), nine feruloylagmatine analogues were designed and synthesized from ferulic acid and agmatine. The structures of the synthesized compounds were confirmed by 1H NMR, 13C NMR and mass spectra, among which compounds 5f-5i were novel compounds. The results of preliminary pharmacological test showed that some of the compounds possessed strong NHE-1 inhibitory activity, among which compounds 5a, 5b and 6c were more potent than cariporide in NHE-1 inhibition.

Modulación inflamatoria en el shock traumático: [revisión] / Inflammatory modulation in traumatic shock: [review]

Hemorrhagic hypovolemic shock secondary to trauma is an important cause of morbidity and mortality worldwide. During the last few years, new concepts have emerged and the guidelines of fluid resuscitation in these patients have been redefined. The concept of hypotensive resuscitation has been established and new colloid solutions based on starch have been manufactured, been hydroxyethyl starch in a balanced electrolytic solution, the most studied and successful one. It has been reported, as well, the positive effects of the pharmacologic modulation of the inflammatory pathways in experimental model subjects submitted to hypovolemic shock. Products such as, ethyl pyruvate and the Na+/H+ type 1 inhibitor, BIIB513, have been Studies only experimentally in rodent models using colloids as the primary resuscitation fluid. The significant improvement in the hemodinamyc, pattern and the cardiac and inflammatory indexes and mediators, has created the basis for their use in clinical trials in the near future. The systemic inflammatory response is an important cause of multiple organ failure that increases the late mortality of patients surviving the initial early phases of hypovolemic traumatic shock and its experimental modulation in rodent models with products such as ethyl pyruvate and BIIB513 has produced excellent in vivo and in vitro results.

Universalmente se considera el Shock hipovolémico de origen hemorrágico como una importante causa de morbi-mortalidad. Durante los últimos años se ha redefinido los conceptos de la reanimación con líquidos intravenosos en los pacientes con choque hipovolémico y establecido los conceptos de reanimación hipotensa con el uso de nuevos coloides derivados del almidón, tales como el hidroxietil-almidón en solución electrolítica balanceada (Hextend®). Así mismo, se ha reportado el beneficio que conlleva el uso de modificadores de la cascada inflamatoria en modelos experimentales de sujetos sometidos a choque hipovolémico hemorrágico. Productos como el etil piruvato y la BIIB513, un inhibidor selectivo del intercambiador Na+/H+ tipo 1, han sido estudiados sólo experimentalmente en modelos roedores, empleando coloides como principal elemento de reanimación. Al mejorar el perfil hemodinámico, parámetros cardíacos y niveles de mediadores inflamatorios, estos compuestos constituyen una base cierta para ser incluidos en estudios clínicos en un futuro próximo. La respuesta inflamatoria sistémica está íntimamente implicada en la patogénesis de la Falla Orgánica Múltiple, aumentando la mortalidad tardía de pacientes que sobreviven las etapas tempranas del shock hipovolémico hemorrágico traumático. Su modulación experimental con el etil piruvato o bien la BIIB513 ha dado excelente resultado tanto en modelos experimentales in vivo como in vitro.

High Dose Vitamin D3 Attenuates the Hypocalciuric Effect of Thiazide in Hypercalciuric Rats

Thiazide is known to decrease urinary calcium excretion. We hypothesized that thiazide shows different hypocalciuric effects depending on the stimuli causing hypercalciuria. The hypocalciuric effect of hydrochlorothiazide (HCTZ) and the expression of transient receptor potential vanilloid 5 (TRPV5), calbindin-D(28K), and several sodium transporters were assessed in hypercalciuric rats induced by high calcium diet and vitamin D3. Urine calcium excretion and the expression of transporters were measured from 4 groups of Sprague-Dawley rats; control, HCTZ, high calcium-vitamin D, and high calcium-vitamin D with HCTZ groups. HCTZ decreased urinary calcium excretion by 51.4% in the HCTZ group and only 15% in the high calcium-vitamin D with HCTZ group. TRPV5 protein abundance was not changed by HCTZ in the high calcium-vitamin D with HCTZ group compared to the high calcium-vitamin D group. Protein abundance of NHE3, SGLT1, and NKCC2 decreased in the hypercalciuric rats, and only SGLT1 protein abundance was increased by HCTZ in the hypercalciuric rats. The hypocalciuric effect of HCTZ is attenuated in high calcium and vitamin D-induced hypercalciuric rats. This attenuation seems to have resulted from the lack of HCTZ's effect on protein abundance of TRPV5 in severe hypercalciuric condition induced by high calcium and vitamin D.