Expression of isoforms of the Na<sup>+</sup>/H<sup>+</sup>exchanger in M-1 mouse cortical collecting duct cells

Hill, Christopher; Giesberts, A N; White, S. J.

doi:10.1152/ajprenal.00291.2000

Cited by 8 publications

(6 citation statements)

References 29 publications

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“…In fact, using RT-PCR and an array of NHE primer pairs, we have detected NHE1, 2, and 4 -8 in these principal cell models (not shown). These early data corroborate past work (15,17). We could not PCR amplify NHE3-the predominant NHE in the apical membrane of the proximal tubule-despite the use of at least six different primer pairs.…”

Section: Discussionsupporting

confidence: 91%

“…In the current study, we present immunohistochemical evidence consistent with apical NHE expression of cilium-deficient principal cells derived from the renal collecting duct. In most studies (8,12,40,41), except for a couple (15,17), investigators find NHE expression exclusively on the basolateral surface of collecting duct cells. Indeed, we also found NHE1 predominantly localized to the basolateral membrane of collecting duct cells in kidney sections from control vs. orpk mice (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Increased Na⁺/H⁺ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Olteanu¹,

Liu²,

et al. 2012

American Journal of Physiology-Cell Physiology

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Pathophysiological anomalies in autosomal dominant and recessive forms of polycystic kidney disease (PKD) may derive from impaired function/formation of the apical central monocilium of ductal epithelia such as that seen in the Oak Ridge polycystic kidney or orpk ( Ift88Tg737Rpw) mouse and its immortalized cell models for the renal collecting duct. According to a previous study, Na/H exchanger (NHE) activity may contribute to hyperabsorptive Na+movement in cilium-deficient (“mutant”) cortical collecting duct principal cell monolayers derived from the orpk mice compared with cilium-competent (“rescued”) monolayers. To examine NHE activity, we measured intracellular pH (pHi) by fluorescence imaging with the pH-sensitive dye BCECF, and used a custom-designed perfusion chamber to control the apical and basolateral solutions independently. Both mutant and rescued monolayers exhibited basolateral Na+-dependent acid-base transporter activity in the nominal absence of CO2/HCO3−. However, only the mutant cells displayed appreciable apical Na+-induced pHirecoveries from NH4+prepulse-induced acid loads. Similar results were obtained with isolated, perfused collecting ducts from orpk vs. wild-type mice. The pHidependence of basolateral cariporide/HOE-694-sensitive NHE activity under our experimental conditions was similar in both mutant and rescued cells, and 3.5- to 4.5-fold greater than apical HOE-sensitive NHE activity in the mutant cells (pHi6.23–6.68). Increased apical NHE activity correlated with increased apical NHE1 expression in the mutant cells, and increased apical localization in collecting ducts of kidney sections from orpk vs. control mice. A kidney-specific conditional cilium-knockout mouse produced a more acidic urine compared with wild-type littermates and became alkalotic by 28 days of age. This study provides the first description of altered NHE activity, and an associated acid-base anomaly in any form of PKD.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Increased Na⁺/H⁺ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Olteanu¹,

Liu²,

et al. 2012

American Journal of Physiology-Cell Physiology

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“…The proximal tubule reclaims ϳ75% of filtered bicarbonate through Na/H exchanger-and H ϩ -ATPase-mediated proton secretion (15): both transporters are regulated by extracellular nucleotides in renal and nonrenal cell lines (1,12,16,24,29). The present study extended those observations made in isolated cells to a more complex biological system.…”

Section: Discussionsupporting

confidence: 69%

“…In A6 cells, a cell line of distal tubule phenotype derived from Xenopus laevis, basolateral but not apical P2Y 1 receptor activation inhibits Na/H exchange (1). In the murine M1 cell line, which resembles the principal cell of the cortical collecting duct, the reverse applies: extracellular ATP reduces intracellular pH when applied to the apical but not basolateral membrane (16).…”

mentioning

confidence: 99%

Inhibition of bicarbonate reabsorption in the rat proximal tubule by activation of luminal P2Y₁receptors

Bailey¹

2004

American Journal of Physiology-Renal Physiology

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The present study used a stationary microperfusion technique to investigate in vivo the effect of P2Y1 receptor activation on bicarbonate reabsorption in the rat proximal tubule. Proximal tubules were perfused with a bicarbonate Ringer solution before flow was stopped by means of an oil block. The recovery of lumen pH from the initial value (pH 8.0) to stationary values (pH approximately 6.7) was recorded by a H+-sensitive microelectrode inserted downstream of the perfusion pipette and oil block. The stationary pH value and the t(1/2) of pH recovery were used to calculate bicarbonate reabsorption (JHCO3). Both EIPA and bafilomycin A1 caused significant reductions in proximal tubule JHCO3, consistent with the established contributions of Na/H exchange and H+-ATPase to proximal tubule HCO3 reabsorption. The nucleotides ADP and, to a lesser extent, ATP reduced JHCO3 but AMP and UTP were without effect. 2MeSADP, a highly selective agonist of the P2Y1 receptor, reduced JHCO3 in a dose-dependent manner. MRS-2179, a P2Y1 receptor-specific antagonist, abolished the effect of 2MeSADP, whereas theophylline, an antagonist of adenosine (P1) receptors, did not. The inhibitory action of 2MeSADP was blocked by inhibition of protein kinase C and reduced by inhibition of protein kinase A. The effects of EIPA and 2MeSADP were not additive. The data provide functional evidence for P2Y1 receptors in the apical membrane of the rat proximal tubule: receptor activation impairs acidification in this nephron segment.

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“…The reverse transcriptase was inactivated by heating the mixture for 5 min at 90°C. Specific primers for NHE1, NHE2, NHE3, and ␤-actin (Table 1) were designed from sequences of the coding regions corresponding to mouse NHE1-3 and ␤-actin genes (13,31,42). PCR was performed using the GeneAmp PCR system 2700 (Applied Biosystems) using Taq polymerase.…”

Section: Rt-pcrmentioning

confidence: 99%

Chronic hypoxia elevates intracellular pH and activates Na⁺/H⁺exchange in pulmonary arterial smooth muscle cells

Rios¹,

Fallon²,

Wang³

et al. 2005

American Journal of Physiology-Lung Cellular and Molecular Phys

116

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(CH), caused by many lung diseases, results in pulmonary hypertension due, in part, to increased muscularity of small pulmonary vessels. Pulmonary arterial smooth muscle cell (PASMC) proliferation in response to growth factors requires increased intracellular pH (pH i) mediated by activation of Na ϩ /H ϩ exchange (NHE); however, the effect of CH on PASMC pH i homeostasis is unknown. Thus we measured basal pH i and NHE activity and expression in PASMCs isolated from mice exposed to normoxia or CH (3 wk/10% O 2). pHi was measured using the pH-sensitive fluorescent dye BCECF-AM. NHE activity was determined from Na ϩ -dependent recovery from NH 4-induced acidosis, and NHE expression was determined by RT-PCR and immunoblot. PASMCs from chronically hypoxic mice exhibited elevated basal pH i and increased NHE activity. NHE1 was the predominate isoform present in mouse PASMCs, and both gene and protein expression of NHE1 was increased following exposure to CH. Our findings indicate that exposure to CH caused increased pH i, NHE activity, and NHE1 expression, changes that may contribute to the development of pulmonary hypertension, in part, via pH-dependent induction of PASMC proliferation. pulmonary hypertension MANY CHRONIC LUNG DISEASES cause prolonged alveolar hypoxia, resulting in the development of pulmonary hypertension. The elevation in pulmonary arterial pressure is due to both active contraction of vascular smooth muscle and structural remodeling (21,24,36,38). Pulmonary vascular remodeling in response to chronic hypoxia has been well characterized and includes pulmonary arterial smooth muscle cell (PASMC) hypertrophy and hyperplasia, intimal thickening, and extension of smooth muscle into previously nonmuscular arterioles (21, 36). The exact cellular mechanisms governing hypoxia-induced PASMC growth are not completely known; however, changes in intracellular pH (pH i ) have been demonstrated to be required for cell growth and/or proliferation in pulmonary (33) and systemic tissue (6,17,22), suggesting a possible pivotal role for H ϩ homeostasis in mediating this response.

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Expression of isoforms of the Na⁺/H⁺exchanger in M-1 mouse cortical collecting duct cells

Cited by 8 publications

References 29 publications

Increased Na⁺/H⁺ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Increased Na⁺/H⁺ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Inhibition of bicarbonate reabsorption in the rat proximal tubule by activation of luminal P2Y₁receptors

Chronic hypoxia elevates intracellular pH and activates Na⁺/H⁺exchange in pulmonary arterial smooth muscle cells

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Expression of isoforms of the Na+/H+exchanger in M-1 mouse cortical collecting duct cells

Cited by 8 publications

References 29 publications

Increased Na+/H+ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Increased Na+/H+ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Inhibition of bicarbonate reabsorption in the rat proximal tubule by activation of luminal P2Y1receptors

Chronic hypoxia elevates intracellular pH and activates Na+/H+exchange in pulmonary arterial smooth muscle cells

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Expression of isoforms of the Na⁺/H⁺exchanger in M-1 mouse cortical collecting duct cells

Increased Na⁺/H⁺ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Increased Na⁺/H⁺ exchanger activity on the apical surface of a cilium-deficient cortical collecting duct principal cell model of polycystic kidney disease

Inhibition of bicarbonate reabsorption in the rat proximal tubule by activation of luminal P2Y₁receptors

Chronic hypoxia elevates intracellular pH and activates Na⁺/H⁺exchange in pulmonary arterial smooth muscle cells