Therapeutic Effects of Add-On Tenapanor for Hemodialysis Patients with Refractory Hyperphosphatemia.

INTRODUCTION: Phosphate binders are used to treat hyperphosphatemia. Some patients have inappropriately controlled serum phosphorus levels, which may occur for many reasons, including a high pill burden and adverse events (AEs). Tenapanor selectively inhibits the passive paracellular transfer of phosphate in the gastrointestinal tract, thereby reducing serum phosphorus levels. This novel mechanism of action may contribute to improved phosphate management. The efficacy and safety of tenapanor have not been evaluated in Japanese patients with high serum phosphorus levels despite treatment with phosphate binders. This study aimed to assess the efficacy and safety of add-on tenapanor therapy for reducing serum phosphorus levels in this population. METHODS: This multicenter, double-blind, randomized, placebo-controlled trial enrolled patients with refractory hyperphosphatemia undergoing hemodialysis. Patients were randomly assigned in a 1:1 ratio to receive tenapanor or placebo as an add-on to their phosphate binder regimen for 6 weeks. Change in serum phosphorus levels at week 6 (day 43) compared with the baseline value (day 1, week 0) (primary endpoint), achievement of target serum phosphorus levels (serum phosphorus level ≤6.0 or ≤5.5 mg/dL), and safety, based on all AEs and drug-related AEs, were among the outcomes evaluated. RESULTS: In total, 24 patients were randomly assigned to the placebo group and 23 to the tenapanor group. The mean serum phosphorus level decreased from 7.01 mg/dL on day 1 to 6.69 mg/dL on day 43 in the placebo group and from 6.77 mg/dL on day 1 to 4.67 mg/dL on day 43 in the tenapanor group. In the placebo and tenapanor groups (modified intent-to-treat population), the mean (standard deviation) change in the serum phosphorus level at day 43 (last observation carried forward [LOCF]) was 0.08 (1.52) mg/dL and -1.99 (1.24) mg/dL, respectively, with a between-group difference of -2.07 (95% confidence interval: -2.89, -1.26; p < 0.001). The target achievement rate (serum phosphorus level ≤6.0 mg/dL at week 6 [LOCF]) was 37.5 and 87.0% in the placebo and tenapanor groups, respectively. Diarrhea was the most common drug-related AE, and it occurred in 8.3 and 65.2% of patients in the placebo and tenapanor groups, respectively. No specific AEs were observed with add-on tenapanor or with phosphate binders. DISCUSSION/CONCLUSION: Therapy with existing phosphate binders and add-on tenapanor resulted in a significant decrease in serum phosphorus level compared with the placebo group in patients with refractory hyperphosphatemia despite treatment with phosphate binders. No new safety signals were raised, and add-on tenapanor was generally well tolerated.

Na+/H+ Exchanger Regulates Amino Acid-Mediated Autophagy in Intestinal Epithelial Cells.

BACKGROUND/AIMS: Dysfunctional autophagy has been reported to be associated with aberrant intestinal metabolism. Amino acids can regulate autophagic activity in intestinal epithelial cells (IECs). Na+/H+-exchanger 3 (NHE3) has been found to participate in the absorption of amino acids in the intestine, but whether NHE3 is involved in the regulation of autophagy in IECs is unclear. METHODS: In the present study, an amino acid starvation-induced autophagic model was established. Then, the effects of alanine and proline with or without the NHE inhibitor 5-(N-ethyl-N-isopropyl) amiloride (EIPA) were evaluated. Autophagy was examined based on the microtubule-associated light chain 3 (LC3) levels, transmission electron microscopy (TEM), tandem GFP-mCherry-LC3 construct, sequestosome-1 (SQSTM1, P62) mRNA and protein levels, and autophagy-related gene (ATG) 5, 7, and 12 expression levels. The autophagic flux was evaluated as the ratio of yellow (autophagosomes) to red (autolysosomes) LC3 puncta. RESULTS: Following amino acid starvation, we found the LC3-II and ATG expression levels were enhanced in the IEC-18 cells. An increase in the number of autophagic vacuoles was concomitantly observed by TEM and confocal microscopy. Based on the results, supplementation with either alanine or proline depressed autophagy in the IEC-18 cells. Consistent with the elevated LC3-II levels, ATG expression increased upon NHE3 inhibition. Moreover, the mCherry-GFP-LC3 autophagic puncta representing both autophagosomes and autolysosomes per cell increased after EIPA treatment. CONCLUSIONS: These results demonstrate that NHE (most likely NHE3) may participate in the amino acid regulation of autophagy in IECs, which would aid in the design of better treatments for intestinal inflammation.

Reactive oxygen species partially mediate high dose angiotensin II-induced positive inotropic effect in cat ventricular myocytes.

BACKGROUND: Reactive oxygen species, such as superoxide, are being increasingly recognized as key components of a vast array of signaling pathways. Angiotensin II is a well-recognized stimulus for superoxide production through NADPH oxidase activation and opening of the mitochondrial ATP-sensitive potassium channels (mKATP). A role for this mechanism has been proposed to explain several physiological effects of the peptide. The aim of this study was to evaluate the involvement of this mechanism in the inotropic response to 100nmol/L angiotensin II. METHODS: Sarcomere shortening and intracellular pH (BCECF-epifluorescence technique) were evaluated in isolated cat ventricular myocytes placed in a perfusion chamber on the stage of an inverted microscope. Myocardial superoxide production was evaluated by the lucigenin quimioluminiscence method. RESULTS: Angiotensin II (100nmol/L) increased~70% sarcomere shortening, effect that was only partially prevented by NADPH oxidase inhibition, mKATP channel blockade or inhibition of the cardiac Na(+)/H(+) exchanger (NHE-1). Moreover, angiotensin II stimulates NHE-1 activity by a NADPH oxidase-dependent mechanism. Myocardial superoxide production was also increased by angiotensin II, and this action was completely prevented either by NADPH oxidase inhibition or mKATP channel blockade. CONCLUSIONS: The positive inotropic response to 100nmol/L angiotensin II is due to both ROS/NHE-1 dependent and independent pathways, this being a point of divergence with the signaling previously described to be triggered by lower concentrations of angiotensin II (i.e.: 1nmol/L).

A minireview on NHE1 inhibitors. A rediscovered hope in oncohematology.

BACKGROUND: Na(+)/H(+) exchanger-1 (NHE-1) is involved in pH regulation and is up-regulated in different malignancies. Activation of NHE-1 is one way for allowing cells to avoid intracellular acidification and protect them against apoptosis. Inhibitors of NHE-1 are able to decrease intracellular pH and induce apoptosis. Some statins can also act by partial inhibition of NHE-1. This review presents progress in understanding the mechanisms of action of these inhibitors, connections with certain genetic mutations and acquired treatment resistance, as well as new patents on them. METHODS: A MEDLINE search for original and review articles using key terms, Na(+)/H(+) exchanger, leukemia, cariporide, and amiloride. Recent patents with NHE-1 inhibitors published by United States Patent and Trademark Office are also presented. RESULTS AND CONCLUSIONS: Sorafenib is used for the treatment of acute myeloid leukemia patients carrying internal tandem duplication of fms-like tyrosine kinase 3 (FLT3-ITD) mutation. 5-(N, N-hexamethylene)-amiloride can increase the suppression of FLT3 signaling by sorafenib. NHE-1 inhibitors are able to increase the sensitivity of chronic myeloid leukemia cells to tyrosine kinase inhibitors, including through the inhibition of P-glycoprotein. NHE-1 inhibitors are promising adjuvant drugs for overcoming acquired resistance to treatment in various malignant hemopathies.

Gastrointestinal Inhibition of Sodium-Hydrogen Exchanger 3 Reduces Phosphorus Absorption and Protects against Vascular Calcification in CKD.

In CKD, phosphate retention arising from diminished GFR is a key early step in a pathologic cascade leading to hyperthyroidism, metabolic bone disease, vascular calcification, and cardiovascular mortality. Tenapanor, a minimally systemically available inhibitor of the intestinal sodium-hydrogen exchanger 3, is being evaluated in clinical trials for its potential to (1) lower gastrointestinal sodium absorption, (2) improve fluid overload-related symptoms, such as hypertension and proteinuria, in patients with CKD, and (3) reduce interdialytic weight gain and intradialytic hypotension in ESRD. Here, we report the effects of tenapanor on dietary phosphorous absorption. Oral administration of tenapanor or other intestinal sodium-hydrogen exchanger 3 inhibitors increased fecal phosphorus, decreased urine phosphorus excretion, and reduced [(33)P]orthophosphate uptake in rats. In a rat model of CKD and vascular calcification, tenapanor reduced sodium and phosphorus absorption and significantly decreased ectopic calcification, serum creatinine and serum phosphorus levels, circulating phosphaturic hormone fibroblast growth factor-23 levels, and heart mass. These results indicate that tenapanor is an effective inhibitor of dietary phosphorus absorption and suggest a new approach to phosphate management in renal disease and associated mineral disorders.

Small molecule inhibition of the Na(+)/H(+) exchange regulatory factor 1 and parathyroid hormone 1 receptor interaction.

We have identified a series of small molecules that bind to the canonical peptide binding groove of the PDZ1 domain of NHERF1 and effectively compete with the association of the C-terminus of the parathyroid hormone 1 receptor (PTH1R). Employing nuclear magnetic resonance and molecular modeling, we characterize the mode of binding that involves the GYGF loop important for the association of the C-terminus of PTH1R. We demonstrate that the common core of the small molecules binds to the PDZ1 domain of NHERF1 and displaces a (15)N-labeled peptide corresponding to the C-terminus of PTH1R. The small size (molecular weight of 192) of this core scaffold makes it an excellent candidate for further elaboration in the development of an inhibitor for this important protein-protein interaction.

Sabiporide improves cardiovascular function and attenuates organ injury from severe sepsis.

BACKGROUND: The aim of the present study was to evaluate the efficacy of orally administered sabiporide, a selective Na(+)/H(+) exchanger inhibitor on whole body protection from severe sepsis in rats. METHODS: Series 1: Sepsis was induced by cecal ligation and puncture (CLP). Animals received treatment of vehicle or sabiporide (10 mg/kg, p.o.). The experiment was terminated 20 h after CLP. Series 2: At 20 h after CLP, the necrotic cecum was excised and the abdominal cavity was washed. The animals were then returned to their cages. The experiment was terminated 7 d after CLP. RESULTS: Series 1: Compared with vehicle treatment, administration of sabiporide prevented hemodynamic derangement and improved cardiac function as evidenced by improved arterial pressure, left ventricle systolic pressure, ±dp/dt max, ejection fraction and fractional shorting, attenuated left ventricle end-diastolic pressure elevation, and wall motion abnormality. Furthermore, administration of sabiporide attenuated intestinal mucosal hyperpermeability and reduced accumulation of abdominal ascites. In addition, treatment with sabiporide also reduced plasma levels of tumor necrosis factor-α, interleukin 6, interleukin 10, cardiac troponin, aspartate aminotransferase, alanine aminotransferase, urea, and lactate, and attenuated neutrophil infiltration in the liver and gut. Series 2: Administration of sabiporide improved the 7-day survival rate after CLP in rats (42% in vehicle group versus 75% in sabiporide group). CONCLUSIONS: Administration of sabiporide improved cardiovascular performance, lessened the inflammatory response, tissue hypoperfusion and multiorgan injury, and most importantly reduced mortality.

Sodium-hydrogen exchanger inhibitory potential of Malus domestica, Musa × paradisiaca, Daucus carota, and Symphytum officinale.

BACKGROUND: The involvement of sodium-hydrogen exchangers (NHE) has been described in the pathophysiology of diseases including ischemic heart and brain diseases, cardiomyopathy, congestive heart failure, epilepsy, dementia, and neuropathic pain. Synthetic NHE inhibitors have not achieved much clinical success; therefore, plant-derived phytoconstituents may be explored as NHE inhibitors. METHODS: In the present study, the NHE inhibitory potential of hydroalcoholic and alkaloidal fractions of Malus domestica, Musa × paradisiaca, Daucus carota, and Symphytum officinale was evaluated. The different concentrations of hydroalcoholic and alkaloidal extracts of the selected plants were evaluated for their NHE inhibitory activity in the platelets using the optical swelling assay. RESULTS: Among the hydroalcoholic extracts, the highest NHE inhibitory activity was shown by M. domestica (IC50=2.350 ± 0.132 µg/mL) followed by Musa × paradisiaca (IC50=7.967 ± 0.451 µg/mL), D. carota (IC50=37.667 ± 2.517 µg/mL), and S. officinale (IC50=249.330 ± 1.155 µg/mL). Among the alkaloidal fractions, the highest NHE inhibitory activity was shown by the alkaloidal fraction of Musa × paradisiacal (IC50=0.010 ± 0.001 µg/mL) followed by D. carota (IC50=0.024 ± 0.002 µg/mL), M. domestica (IC50=0.031 ± 0.005 µg/mL), and S. officinale (IC50=4.233 ± 0.379 µg/mL). The IC50 of alkaloidal fractions was comparable to the IC50 of synthetic NHE inhibitor, EIPA [5-(N-ethyl-N-isopropyl)amiloride] (IC50=0.033 ± 0.004 µg/mL). CONCLUSIONS: It may be concluded that the alkaloidal fractions of these plants possess potent NHE inhibitory activity and may be exploited for their therapeutic potential in NHE activation-related pathological complications.

Functional regulation of cystic fibrosis transmembrane conductance regulator-containing macromolecular complexes: a small-molecule inhibitor approach.

CFTR (cystic fibrosis transmembrane conductance regulator) has been shown to form multiple protein macromolecular complexes with its interacting partners at discrete subcellular microdomains to modulate trafficking, transport and signalling in cells. Targeting protein-protein interactions within these macromolecular complexes would affect the expression or function of the CFTR channel. We specifically targeted the PDZ domain-based LPA2 (type 2 lysophosphatidic acid receptor)-NHERF2 (Na+/H+ exchanger regulatory factor-2) interaction within the CFTR-NHERF2-LPA2-containing macromolecular complexes in airway epithelia and tested its regulatory role on CFTR channel function. We identified a cell-permeable small-molecule compound that preferentially inhibits the LPA2-NHERF2 interaction. We show that this compound can disrupt the LPA2-NHERF2 interaction in cells and thus compromises the integrity of macromolecular complexes. Functionally, it elevates cAMP levels in proximity to CFTR and upregulates its channel activity. The results of the present study demonstrate that CFTR Cl- channel function can be finely tuned by modulating PDZ domain-based protein-protein interactions within the CFTR-containing macromolecular complexes. The present study might help to identify novel therapeutic targets to treat diseases associated with dysfunctional CFTR Cl- channels.

Rapid decrease of intracellular pH associated with inhibition of Na+/H+ exchanger precedes apoptotic events in the MNK45 and MNK74 gastric cancer cell lines treated with 2-aminophenoxazine-3-one.

The effects of Phx-3 on changes in intracellular pH (pHi) in the MKN45 and MKN74 human gastric cancer cell lines were evaluated in order to determine the mechanism for the proapoptotic effects of 2-aminophenoxazine-3-one (Phx-3) on these cells. Phx-3 (100 µM) reduced pHi in MKN45 from 7.45 to 5.8, and in MKN74 from 7.5 to 6.2 within 1 min of engagement with these cells. Such a decrease of pHi was closely correlated with the dose of this phenoxazine and continued for 4 h. The activity of Na+/H+ exchanger isoform l (NHE1), which is involved in H+ extrusion from the cells, was dose-dependently suppressed by Phx-3 in these cells, and was greatly suppressed in the presence of 100 µM Phx-3. This result indicates that the decrease of pHi in MKN45 and MKN74 cells is closely associated with the inhibition of NHE1 in these cells. The morphology of these cells at 24 h after treatment with Phx-3 indicated shrinkage of the cells and condensation of the nuclear chromatin structure, which are characteristic of the apoptotic events in these gastric cancer cells. Cytotoxicity of Phx-3 against MKN45 and MKN74 cells was extensive because almost all MKN45 cells lost viability at 24 h in the presence of 20 µM Phx-3, and nearly 50% of the MKN74 cells lost viability in the presence of 50 µM Phx-3. These results suggest that rapid and extensive decrease of pHi in human gastric cancer MKN45 and MKN74 cells caused by Phx-3 might disturb intracellular homeostasis, leading to apoptotic and cytotoxic events in these cells. Phx-3 is a good candidate for therapeutics of gastric cancer that is intractable to conventional chemopreventive therapies.

Ginseng inhibits cardiomyocyte hypertrophy and heart failure via NHE-1 inhibition and attenuation of calcineurin activation.

BACKGROUND: Ginseng is a medicinal plant used widely in Asia that has gained popularity in the West during the past decade. Increasing evidence suggests a therapeutic role for ginseng in the cardiovascular system. The pharmacological properties of ginseng are mainly attributed to ginsenosides, the principal bioactive constituents in ginseng. The present study was carried out to determine whether ginseng exerts a direct antihypertrophic effect in cultured cardiomyocytes and whether it modifies the heart failure process in vivo. Moreover, we determined the potential underlying mechanisms for these actions. METHODS AND RESULTS: Experiments were performed on cultured neonatal rat ventricular myocytes as well as adult rats subjected to coronary artery ligation (CAL). Treatment of cardiomyocytes with the α(1) adrenoceptor agonist phenylephrine (PE) for 24 hours produced a marked hypertrophic effect as evidenced by significantly increased cell surface area and ANP gene expression. These effects were attenuated by ginseng in a concentration-dependent manner with a complete inhibition of hypertrophy at a concentration of 10 µg/mL. Phenylephrine-induced hypertrophy was associated with increased gene and protein expression of the Na(+)-H(+) exchanger 1 (NHE-1), increased NHE-1 activity, increased intracellular concentrations of Na(+) and Ca(2+), enhanced calcineurin activity, increased translocation of NFAT3 into nuclei, and GATA-4 activation, all of which were significantly inhibited by ginseng. Upregulation of these systems was also evident in rats subjected to 4 weeks of CAL. However, animals treated with ginseng demonstrated markedly reduced hemodynamic and hypertrophic responses, which were accompanied by attenuation of upregulation of NHE-1 and calcineurin activity. CONCLUSIONS: Taken together, our results demonstrate a robust antihypertrophic and antiremodeling effect of ginseng, which is mediated by inhibition of NHE-1-dependent calcineurin activation.

Inhibition of Na+/H+ exchanger isoform 1 is neuroprotective in neonatal hypoxic ischemic brain injury.

We investigated the role of Na(+)/H(+) exchanger isoform 1 (NHE-1) in neonatal hypoxia/ischemia (HI). HI was induced by unilateral ligation of the left common carotid artery in postnatal day 9 (P9) mice, and subsequent exposure of animals to 8% O(2) for 55 min. A pre/posttreatment group received a selective and potent NHE-1 inhibitor HOE 642 (0.5 mg/kg, intraperitoneally) 5 min before HI, then at 24 and 48 h after HI. A posttreatment group received HOE 642 (0.5 mg/kg) at 10 min, 24 h, and 48 h after HI. Saline injections were used as vehicle controls. The vehicle-control brains at 72 h after HI exhibited neuronal degeneration in the ipsilateral hippocampus, striatum, and thalamus, as identified with Fluoro-Jade C positive staining and loss of microtubule-associated protein 2 (MAP2) expression. NHE-1 protein was upregulated in glial fibrillary acidic protein-positive reactive astrocytes. In HOE 642-treated brains, the morphologic hippocampal structures were better preserved and displayed less neurodegeneration and a higher level of MAP2 expression. Motor-learning deficit was detected at 4 weeks of age after HI in the vehicle control group. Inhibition of NHE-1 in P9 mice not only reduced neurodegeneration during the acute stage of HI but also improved the striatum-dependent motor learning and spatial learning at 8 weeks of age after HI. These findings suggest that NHE-1-mediated disruption of ionic homeostasis contributes to striatal and CA1 pyramidal neuronal injury after neonatal HI.

The effects of amiloride, a Na+-H+ exchange inhibitor, on iliac artery stenosis after balloon injury in rabbits.

This study was designed to explore the effects of amiloride, a Na+-H+ exchange (NHE) inhibitor, on vessel stenosis by observing the expression of NHE-1 protein in vascular smooth muscle (VSM) after balloon injury and the effects of amiloride on VSM cell proliferation, migration, and excretion of extracellular matrices (ECMs). A total of 32 adult male New Zealand white rabbits were randomly divided into a balloon injury group (BG), an amiloride-treated group (AG), and a sham-operated group (SG). The left iliac artery was injured by inflating a 2.5 mm x 20 mm Foley catheter in BG and AG rabbits; in SG rabbits, the Foley catheter was inserted but not inflated. Amiloride (5 mg x kg(-1) x d(-1)) was injected intraperitoneally in AG and the same volume of distilled water was used in BG 3 days before balloon injury and for 28 days after the injury. The left iliac artery was stained by hematoxylin-eosin, alpha-actin, and Masson's trichrome to observe the vessel cava, neointima, media layer, and ECMs. NHE-1 proteins of the VSM were detected by Western blotting. A narrowing of the arterial cava, neointima formation, and thickened VSM layer were observed 28 days after balloon injury in BG and AG. However, in AG, the vessel cava was not as narrowed as that of BG and the intimal areas were to a lesser extent than in BG. In AG, the alpha-actin-positive areas and the ECM areas in the neointima were increased compared with SG, but to a lesser extent than in BG. The expression of NHE-1 protein in VSM was increased in BG and AG after balloon injury; however, the levels in AG were significantly less than in BG. In conclusion, VSM cell proliferation, migration, and excretion of ECMs contributed to vessel stenosis in the BG and AG rabbits. The expression of NHE-1 protein in VSM increased after balloon injury. Amiloride, an inhibitor of NHE-1, can limit the development of vessel stenosis through inhibition of VSM cell proliferation, migration, and excretion of ECMs.

Age dependency of the cariporide-mediated cardio-protection after simulated ischemia in isolated human atrial heart muscles.

Experimental and clinical investigations suggest that blockade of Na(+)/H(+) exchange (NHE) with cariporide provides functional protection during ischemia and reperfusion in mature hearts. The benefit on aged human myocardium is unknown. Therefore, the impact of cardiac aging on cardio-protection by cariporide after prolonged ischemia was studied in isolated myocardium of adult (or=70 years) patients with coronary artery disease. Isolated atrial trabeculae were subjected to 30 min of simulated ischemia with and without cariporide, and early post-ischemic contractile recovery was determined. During the reoxygenation period, trabeculae of adults, but not those of old or very old patients, improved after treatment with cariporide. After 90 min of reoxygenation, cariporide-treated adult trabeculae developed 41+/-5% of their pre-ischemic force (non-treated control group, 27+/-5%; P<0.05), and old trabeculae recovered to 41+/-7% (control, 25+/-6%), whereas very old trabeculae recovered to only 26+/-2% (control, 28+/-6%). Trabeculae of all patients <70 years with CCS stage I-II angina pectoris recovered well (45+/-6%; control, 22+/-5%; P<0.01), which was in contrast to patients with CCS stage III (34+/-4%; control, 31+/-5%). Subsequent immunoblot analyses indicated no concomitant alterations in the myocardial NHE1 protein level depending on age. In very old myocardium, higher levels of active p38MAPK in atrial trabeculae after ischemia pointed at an increased cellular stress, which was even more pronounced after post-ischemic reperfusion. In summary, cariporide is protective against ischemia-reperfusion injury in mature human hearts but has no benefit on the post-ischemic functional recovery of the aging myocardium.

Rational design of a nonpeptide general chemical scaffold for reversible inhibition of PDZ domain interactions.

Novel small molecules were designed to specifically target the ligand-binding pocket of a PDZ domain. Iterative molecular docking and modeling allowed the design of an indole scaffold 10a as a reversible inhibitor of ligand binding. The 10a scaffold inhibited the interaction between MAGI-3 and PTEN and showed cellular activities that are consistent with the inhibition of NHERF-1 function.

Effects of bafilomycin A1, a vacuolar type H+ ATPase inhibitor, on the thermosensitivity of a human pancreatic cancer cell line.

PURPOSE: It has been known that the thermosensitivity of tumour cells can be increased by lowering intra-cellular pH (pHi) by inhibiting pHi control mechanisms. The pHi is partially controlled by transport of H+ from cytoplasm into endocytic and secretary systems in the cells mediated by vacuolar type H+ATPase and also by transport of H+ through plasma membrane. METHODS: This study investigated the effects the bafilomycine A1, an inhibitor of the vacuolar type H+ATPase and the EIPA, an inhibitor of the Na+/H+ exchanger in plasma membrane, on thermosensitivity of AsPC-1 cells, a human pancreatic cancer cell line. It also investigated the effects of combination of bafilomycine A1 and EIPA. RESULTS: The treatment of cancer cells with bafilomycine A1 or EIPA individually slightly lowered pHi of the cells in vitro and increased the thermosensitivity of the cells. CONCLUSION: The combination of these two drugs significantly lowered pHi and increased thermosensitivity of cancer cells in vitro and enhanced the heat-induced the growth delay of AsPC-1 tumours grown s.c in the legs of BALB/cA nude mice.

Functional observational battery and motor activity in rats after single administration of two NHE 1 inhibitors.

Two tests, a functional observational battery (FOB) and measurement of motor activity, have been used to screen the two NHE inhibitors EMD 96785 and EMD 125021 for neurobehavioral effects. These two NHE inhibitors, which exhibit a marked selectivity for the NHE 1 isoform, are under development in the research laboratories of Merck KGaA. NHE inhibitors are developed for the treatment of acute myocardial infarction and chronic heart failure. In prior studies with EMD 96785 and EMD 125021, clinical symptoms, such as uncoordinated movements and weakness of the hindlimbs, were detected in rats. The aim of this study was the evaluation of clinical findings in more detail using a FOB and measurement of motor activity in 96 female rats. The time course and reversibility of the adverse effects were investigated. The animals were treated with EMD 96785 or EMD 125021 by intravenous injection at a single dose of 100 mg/kg and four different time points (2 h, 1 day, 7 days and 21 days after treatment) were chosen for the clinical examination. This neurobehavioral test battery clearly detected neurological activity and defined time-course characteristics after treatment with EMD 96785 or EMD 125021. The various clinical parameters were grouped into functional-related domains and most alterations were seen in the domains of central nervous system and neuromuscular system. The most prominent clinical findings were seen with the pharmacologically more potent NHE inhibitor EMD 125021 when compared to EMD 96785. The clinical symptoms were proven to be reversible by 7 days after the single treatment for both compounds.

Myocardial protection at a crossroads: the need for translation into clinical therapy.

Over the past 30 years, hundreds of experimental interventions (both pharmacologic and nonpharmacologic) have been reported to protect the ischemic myocardium in experimental animals; however, with the exception of early reperfusion, none has been translated into clinical practice. The National Heart, Lung, and Blood Institute convened a working group to discuss the reasons for the failure to translate potential therapies for protecting the heart from ischemia and reperfusion and to recommend new approaches to accomplish this goal. The Working Group concluded that cardioprotection in the setting of acute myocardial infarction, cardiac surgery, and cardiac arrest is at a crossroads. Present basic research approaches to identify cardioprotective therapies are inefficient and counterproductive. For 3 decades, significant resources have been invested in single-center studies that have often yielded inconclusive results. A new paradigm is needed to obviate many of the difficulties associated with translation of basic science findings. The Working Group urged a new focus on translational research that emphasizes efficacy and clinically relevant outcomes, and recommended the establishment of a system for rigorous preclinical testing of promising cardioprotective agents with clinical trial-like approaches (ie, blinded, randomized, multicenter, and adequately powered studies using standardized methods). A national preclinical research consortium would enable rational translation of important basic science findings into clinical use. The Working Group recommended that the National Institutes of Health proactively intervene to remedy current problems that impede translation of cardioprotective therapies. Their specific recommendations include the establishment of a preclinical consortium and the performance of 2 clinical studies that are likely to demonstrate effectiveness (phase III clinical trials of adenosine in acute myocardial infarction and cardiac surgery).