Pharmacodynamic characteristics and cardioprotective effects of new NHE1 inhibitors

Kim, Juno; Jung, Yi Sook; Han, Won Sun; Kim, Mi Young; Namkung, W.; Lee, Byung Ho; Yi, Kyu Yang; Yoo, Sung Eun; Lee, Min Goo; Kim, Kyung Hwan

doi:10.1016/j.ejphar.2007.03.056

Cited by 19 publications

(5 citation statements)

References 28 publications

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“…Briefly, cells were loaded with a sodium ion indicator, sodium benzofuran isophthalate (SBFI), and treated for 30 minutes with combinations of the following drugs: ouabain (OUB, 100 µmol/L, NaKATPase inhibitor), fenoldopam (FEN, 1 µmol/L, D 1 -like receptor agonist), LE300 (10 µmol/L, D 1 -like receptor antagonist), EIPA (10 µmol/L, NHE inhibitor), S3226 (10 µmol/L, NHE3 inhibitor) 22–23 and cariporide (HOE-642, 10 µmol/L, NHE1 inhibitor). 24 The specificity of the assay was verified by the positive inhibition seen with S3226 (NHE3 selective) and negative inhibition seen with cariporide (NHE1 selective). Time-lapse ratiometric images were acquired every three minutes.…”

Section: Methodsmentioning

confidence: 95%

HK-2 Human Renal Proximal Tubule Cells as a Model for G Protein–Coupled Receptor Kinase Type 4–Mediated Dopamine 1 Receptor Uncoupling

et al. 2010

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HK-2 human renal proximal tubule cells (RPTC) are commonly used in the in vitro study of “normal” RPTCs. We recently discovered that HK-2 cells are uncoupled from dopamine-1 receptor (D1R) adenylyl cyclase (AC) stimulation. We hypothesized that G protein coupled receptor kinase type 4 (GRK4) single nucleotide polymorphisms (SNPs) may be responsible for the D1R/AC uncoupling in HK-2. This hypothesis was tested by genotyping GRK4 SNPs, measuring D1-like receptor agonist (fenoldopam)stimulated cAMP accumulation, quantifying D1R inhibition of sodium transport, and testing the ability of GRK4 siRNA to reverse the D1R/AC uncoupling. We compared HK-2 to 2 normally coupled human RPTC cell lines (nRPTC) and 2 uncoupled RPTC cell lines (uRPTC). The HK-2 cell line was found to have 4 out of 6 potential GRK4 SNPs known to uncouple the D1R from AC (namely R65L, A142V, and A486V). AC response to fenoldopam stimulation was increased in the two nRPTC cell lines (FEN 2.02±0.05-fold and 2.33±0.19-fold over control, P<0.001, N=4), but not in the two uncoupled or HK-2 cell lines. GRK4 siRNA rescued the fenoldopam-mediated AC stimulation in the uncoupled cells, including HK-2. The expected fenoldopam -mediated inhibition of sodium hydrogen exchanger type 3 was absent in HK-2 (N=6) and uRPTCs (N=6), but was observed in the two nRPTCs (−25.41±4.7% and −27.36±2.70% (P<0.001, N=6)), which express wild-type GRK4. Despite the fact that HK-2 cells retain many functional characteristics of RPTCs, they are not normal from the perspective of dopaminergic function.

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Section: Methodsmentioning

confidence: 95%

HK-2 Human Renal Proximal Tubule Cells as a Model for G Protein–Coupled Receptor Kinase Type 4–Mediated Dopamine 1 Receptor Uncoupling

et al. 2010

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“…NHE activity was measured following a previously described method with a few modifications ( Kim et al ., 2007 ). Briefly, cells were loaded with a pH-sensitive fluorescent dye - BCECF-AM (acetoxymethyl esters of 2′,7′-bis(2-carboxyethyl)-5,6-carboxyfluorescein, Invitrogen, Carlsbad, CA, USA) and pH i changes were measured.…”

Section: Methodsmentioning

confidence: 99%

Sustained Intracellular Acidosis Triggers the Na⁺/H⁺Exchager-1 Activation in Glutamate Excitotoxicity

Lee

2017

Biomolecules & Therapeutics

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The Na+/H+ exchanger-1 (NHE-1) is a ubiquitously expressed pH-regulatory membrane protein that functions in the brain, heart, and other organs. It is increased by intracellular acidosis through the interaction of intracellular H+ with an allosteric modifier site in the transport domain. In the previous study, we reported that glutamate-induced NHE-1 phosphorylation mediated by activation of protein kinase C-β (PKC-β) in cultured neuron cells via extracellular signal-regulated kinases (ERK)/p90 ribosomal s6 kinases (p90RSK) pathway results in NHE-1 activation. However, whether glutamate stimulates NHE-1 activity solely by the allosteric mechanism remains elusive. Cultured primary cortical neuronal cells were subjected to intracellular acidosis by exposure to 100 μM glutamate or 20 mM NH4Cl. After the desired duration of intracellular acidosis, the phosphorylation and activation of PKC-β, ERK1/2 and p90RSK were determined by Western blotting. We investigated whether the duration of intracellular acidosis is controlled by glutamate exposure time. The NHE-1 activation increased while intracellular acidosis sustained for >3 min. To determine if sustained intracellular acidosis induced NHE-1 phosphorylation, we examined phosphorylation of NHE-1 induced by intracellular acidosis by transient exposure to NH4Cl. Sustained intracellular acidosis led to activation and phosphorylation of NHE-1. In addition, sustained intracellular acidosis also activated the PKC-β, ERK1/2, and p90RSK in neuronal cells. We conclude that glutamate stimulates NHE-1 activity through sustained intracellular acidosis, which mediates NHE-1 phosphorylation regulated by PKC-β/ERK1/2/p90RSK pathway in neuronal cells.

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“…Key examples include 5' N-ethylisopropylamiloride (EIPA) (K i ~0.01-0.02 M for NHE1) and dimethylamiloride (DMA) (K i ~0.023 M) [125]. Substitution of the pyrazine moiety for a phenyl ring or a heterocycle gave rise to the commercialized drugs HOE-642 (cariporide; IC 50 ~ 0.03-0.34 M) and eniporide, and later on, the analogs zoniporide and sabiporide [125; 126] and KR-32570 and KR-33028 [127]. These compounds have been widely used, in particular in studies of the role of NHE1 in cardiac ischemia-reperfusion disorders (for reviews, see [85; 128]).…”

Section: Ii5 Nhe1 Pharmacologymentioning

confidence: 99%

Physiology, Pharmacology and Pathophysiology of the pH Regulatory Transport Proteins NHE1 and NBCn1: Similarities, Differences, and Implications for Cancer Therapy

Boedtkjer

Bunch²,

Pedersen

2012

CPD

126

155

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The Na⁺/H⁺-exchanger 1, NHE1 (SLC9A1) and the electroneutral Na⁺,HCO₃⁻ cotransporter NBCn1 (SLC4A7) are coexpressed in a wide range of tissues. Under normal physiological conditions these transporters play an ostensibly similar role, namely that of net acid extrusion after cellular acidification. In addition, they have been implicated in multiple other cellular processes, including regulation of transepithelial transport, cell volume, cell death/survival balance, and cell motility. In spite of their apparent functional similarity, the two transporters also serve distinctly different functions and are differentially regulated. Here, we provide an update on the basic structure, function, regulation, physiology and pharmacology of NHE1 and NBCn1, with particular focus on the factors responsible for their functional similarities and differences. Finally, we highlight recent findings implicating these transporters in cancer development, and discuss issues relating to NHE1 and NBCn1 as potential targets in cancer treatment.

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Pharmacodynamic characteristics and cardioprotective effects of new NHE1 inhibitors

Cited by 19 publications

References 28 publications

HK-2 Human Renal Proximal Tubule Cells as a Model for G Protein–Coupled Receptor Kinase Type 4–Mediated Dopamine 1 Receptor Uncoupling

HK-2 Human Renal Proximal Tubule Cells as a Model for G Protein–Coupled Receptor Kinase Type 4–Mediated Dopamine 1 Receptor Uncoupling

Sustained Intracellular Acidosis Triggers the Na⁺/H⁺Exchager-1 Activation in Glutamate Excitotoxicity

Physiology, Pharmacology and Pathophysiology of the pH Regulatory Transport Proteins NHE1 and NBCn1: Similarities, Differences, and Implications for Cancer Therapy

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Pharmacodynamic characteristics and cardioprotective effects of new NHE1 inhibitors

Cited by 19 publications

References 28 publications

HK-2 Human Renal Proximal Tubule Cells as a Model for G Protein–Coupled Receptor Kinase Type 4–Mediated Dopamine 1 Receptor Uncoupling

HK-2 Human Renal Proximal Tubule Cells as a Model for G Protein–Coupled Receptor Kinase Type 4–Mediated Dopamine 1 Receptor Uncoupling

Sustained Intracellular Acidosis Triggers the Na+/H+Exchager-1 Activation in Glutamate Excitotoxicity

Physiology, Pharmacology and Pathophysiology of the pH Regulatory Transport Proteins NHE1 and NBCn1: Similarities, Differences, and Implications for Cancer Therapy

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Sustained Intracellular Acidosis Triggers the Na⁺/H⁺Exchager-1 Activation in Glutamate Excitotoxicity