Regulation of Intracellular pH in Single Rat Cortical Neurons in vitro: A Microspectrofluorometric Study

Ouyang, Yi‐Bing; Mellergård, Pekka; Siesjö, Bo K.

doi:10.1038/jcbfm.1993.105

Cited by 51 publications

(25 citation statements)

References 49 publications

(49 reference statements)

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“…In most of these neurons, pH i is regulated back toward normal from an acid load by Na ϩ /H ϩ exchange and from an alkaline load by Cl Ϫ / HCO 3 Ϫ exchange. This is similar to the pattern of pH i regulation found in rat cortical neurons (18). In such Fig.…”

Section: R1159 Ph I Regulation In Medullary Neuronssupporting

confidence: 69%

“…We have previously shown that in response to acidification medullary neurons from all four areas studied exhibit recovery that is mediated solely by Na ϩ /H ϩ exchange, with no contribution from HCO 3 Ϫ -dependent transport (22). In most cells (19), including neurons (3,9,18,20), there is Na ϩ -independent Cl Ϫ /HCO 3 Ϫ exchange, which is believed to acidify the cell in response to an alkaline load. In agreement with these studies, we found evidence for Cl Ϫ /HCO 3 Ϫ exchange in neurons from three of the four areas that we studied (VLM, IO, and Hyp) (Figs.…”

Section: R1158mentioning

confidence: 99%

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Intracellular pH regulation in neurons from chemosensitive and nonchemosensitive areas of the medulla

Ritucci

Chambers-Kersh

Dean

et al. 1998

American Journal of Physiology-Regulatory, Integrative and Comp

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brain stem; central chemoreceptor; carbon dioxide; fluorescence imaging; respiration; Na ϩ /H ϩ exchange THE LEVEL OF CO 2 /H ϩ in the blood is carefully regulated by certain neurons in several areas of the medulla oblongata. These neurons are collectively known as central chemoreceptors. The areas in which these neurons are located are known as chemosensitive areas and include the ventrolateral medulla (VLM), the nucleus of the solitary tract (NTS), and the medullary raphe (16). It is hypothesized that an increased level of CO 2 /H ϩ stimulates the central chemoreceptors, which in turn, via the respiratory central pattern generator neurons (which they presumably innervate), increase ventilation (8). The stimulus to the central chemoreceptors has been the subject of much debate. It has been hypothesized that the stimulus may be an increase in molecular CO 2 , a decrease in extracellular pH (pH o ), a decrease in intracellular pH (pH i ), or a combination of any of the three (1,7,16,24,25,30). We have previously shown that both pH i and pH o may play a role in central chemosensitivity (22).It would seem logical that if a change in pH is the major signaling pathway by which central chemoreceptors monitor a change in blood CO 2 /H ϩ , the manner in which these cells respond to acid/base disturbances should be different from that of cells that are not chemoreceptors (nonchemoreceptors). In a previous study, we found that Na ϩ /H ϩ exchange is the only pH i -regulating mechanism involved during recovery from intracellular acidification in neurons from both chemosensitive (NTS and VLM) and nonchemosensitive [hypoglossal nucleus (Hyp) and inferior olive (IO)] areas of the medulla (22). We also found that neurons from chemosensitive areas (NTS and VLM) respond with a maintained intracellular acidification during hypercapnic acidosis, but exhibit pH i recovery during isohydric hypercapnia. This is in contrast to neurons from nonchemosensitive areas (Hyp and IO) that exhibit pH i recovery even during hypercapnic acidosis (22). These findings suggest that the Na ϩ /H ϩ exchanger is more easily inhibited by a decrease of pH o in neurons from chemosensitive areas versus nonchemosensitive areas.The major aim of the present study was to examine pH i regulation in greater detail in individual neurons from chemosensitive and nonchemosensitive areas of the medulla to investigate whether other differences in pH i regulation are present. It must be noted that these data are from neurons in known chemosensitive areas (16) but that the individual neurons themselves may or may not be chemoreceptors. Our data show the following: 1) intrinsic buffering power (␤ int ) is the same in all neurons tested; 2) removal of extracellular chloride at steady-state pH i results in intracellular alkalinization in all Hyp, IO, and VLM neurons but results in intracellular acidification in most NTS neurons, suggesting that Cl Ϫ /HCO 3 Ϫ exchange is present in all Hyp, IO, and VLM neurons but not in most NTS neurons; 3) steady-state pH i is more depende...

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Section: R1159 Ph I Regulation In Medullary Neuronssupporting

confidence: 69%

Section: R1158mentioning

confidence: 99%

Intracellular pH regulation in neurons from chemosensitive and nonchemosensitive areas of the medulla

Ritucci

Chambers-Kersh

Dean

et al. 1998

American Journal of Physiology-Regulatory, Integrative and Comp

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“…At normal or elevated levels of pH,, Nae-independent HCO3--ClF exchange mediates the loss of HC03-from the cell and thus acts as an acidifying mechanism (e.g. Vaughan-Jones, 1982;Boyarsky et al 1988b;Gaillard & Dupont, 1990;Ou-yang et al 1993). At low levels of pHi, however, this passive exchanger can reverse and couple the influx of HC03-to the efflux of Cl-(see Frelin et al 1988).…”

Section: Solutions and Chemicalsmentioning

confidence: 99%

Characterization of acid extrusion mechanisms in cultured fetal rat hippocampal neurones.

Baxter

Church

1996

The Journal of Physiology

100

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1. We investigated the mechanisms regulating acid extrusion in cultured fetal rat hippocampal neurones loaded with 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein.2. In the absence of HCO3-, removal of external Nae by substitution with N-methyl-Dglucamine caused a sustained intracellular acidification that was not observed when Na+ was replaced by Li+, but neither steady-state intracellular pH (pH1) nor the rate of pH, recovery from an imposed acid load were influenced by amiloride analogues or HOE 694, inhibitors of Na+-H+ exchange in other cell types. In the presence of HC03-, removal of external Na+ or Cl-evoked an intracellular acidification and a 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid-sensitive (DIDS-sensitive) intracellular alkalinization, respectively.Applied alone, however, DIDS elicited a fall in steady-state pHi at room temperature but not at 37 'C. The DIDS-evoked fall in steady-state pHi and the 0 CF-evoked intracellular alkalinization observed in the presence of HC03-at room temperature were dependent on external Na+. 3. At room temperature (18-22°C), but not at 37°C, the transition from HC03-free to HC03--containing medium at a constant pH. produced a net alkalinization that was dependent on external Nae and was inhibited by DIDS or the depletion of internal CF. 4. Recovery of pH, from an acid load imposed in the absence of HC03-was dependent on external Nae. Addition of HC03-to the perfusion medium increased the rate of pH1 recovery from an acid load at room temperature but not at 37 'C. In the presence of HCO3-, DIDS slowed the rate of recovery of pHi from an acid load at both room temperature and at 37°C.5. Recovery of pH1 following an imposed intracellular acidification to pH < 6-5 could occur in the absence of external Na+, providing that HC03-was present in the perfusate. This slow, Nae-independent recovery of pHi from very low levels of intracellular pH was sensitive to DIDS. 6. The results indicate that acid extrusion in cultured fetal rat hippocampal neurones involves primarily two Nae-dependent mechanisms, one HC03-dependent and the other HC03-independent (possibly a Na+-H+ exchanger). Although both mechanisms participate in the maintenance of steady-state pH1 at room temperature, only the HCO3--independent mechanism does so at 37°C.

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“…These are the properties of an AE-like Cl À HCO À 3 exchanger. The role of the Cl À HCO À 3 exchanger under alkaline pH i conditions was first described for cardiac Purkinje fibers by Vaughan-Jones [35] and has subsequently been supported by many studies in mammalian cells [14,20,23,25,30]. Our previous work [34] functionally identified an AE-like Cl À HCO À 3 exchanger active near resting pH i and further showed a clear expression of mRNA for AE2 in these cells.…”

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confidence: 93%

Transport activities involved in intracellular pH recovery following acid and alkali challenges in rat brain microvascular endothelial cells

Nicola

Taylor

Wang

et al. 2008

Pflugers Arch - Eur J Physiol

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Transport activities involved in intracellular pH (pH(i)) recovery after acid or alkali challenge were investigated in cultured rat brain microvascular endothelial cells by monitoring pH(i) using a pH-sensitive dye. Following relatively small acid loads with pH(i) approximately 6.5, HCO(-)(3) influx accounted for most of the acid extrusion from the cell with both Cl(-)-independent and Cl(-)-dependent, Na(+)-dependent transporters involved. The Cl(-)-independent component has the same properties as the NBC-like transporter previously shown to account for most of the acid extrusion near the resting pH(i). Following large acid loads with pH(i) < 6.5, most of the acid extrusion was mediated by Na(+)/H(+) exchange, the rate of which was steeply dependent on pH(i). Concanamycin A, an inhibitor of V-type ATPase, had no effect on the rates of acid extrusion. Following an alkali challenge, the major component of the acid loading leading to recovery of pH(i) occurred by Cl(-)/HCO(-)(3) exchange. This exchange had the same properties as the AE-like transporter previously identified as a major acid loader near resting pH(i). These acid-loading and acid-extruding transport mechanisms together with the Na(+), K(+), ATPase may be sufficient to account not only for pH(i) regulation in brain endothelial cells but also for the net secretion of HCO(-)(3) across the blood-brain barrier.

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Regulation of Intracellular pH in Single Rat Cortical Neurons in vitro: A Microspectrofluorometric Study

Cited by 51 publications

References 49 publications

Intracellular pH regulation in neurons from chemosensitive and nonchemosensitive areas of the medulla

Intracellular pH regulation in neurons from chemosensitive and nonchemosensitive areas of the medulla

Characterization of acid extrusion mechanisms in cultured fetal rat hippocampal neurones.

Transport activities involved in intracellular pH recovery following acid and alkali challenges in rat brain microvascular endothelial cells

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