Metabolic and ionic responses of trout hepatocytes to anisosmotic exposure

Krumschnabel, Gerhard; Gstir, Ronald; Manzl, Claudia; Prem, Caroline; Pafundo, Diego E.; Schwarzbaum, Pablo J.

doi:10.1242/jeb.00370

Cited by 17 publications

(21 citation statements)

References 52 publications

(50 reference statements)

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“…A hypertonicity-induced increase in intracellular Ca 2+ has been observed in trout hepatocytes in a previous study (Krumschnabel et al, 2003), and our data indicated that this was due to Ca 2+ mobilization from intracellular stores accompanied by a sustained Ca 2+ influx from extracellular space (Fig.·3). …”

Section: The Possible Involvement Of [Ca 2+ ]Isupporting

confidence: 84%

“…In support for this, the non-isoform-specific inhibitor amiloride also acidifies the cells but concurrently prevents enhanced acid secretion (Krumschnabel et al, 2003;Ebner et al, 2005). The presence of intracellular NHE isoforms acidifying Golgi-and post-Golgi compartments has been documented in human cells (Nakamura et al, 2005), and in cardiomyocytes cariporide was reported to inhibit the mitochondrial NHE, thereby affecting mitochondrial matrix pH (Ruiz-Meana et al, 2003).…”

Section: Hypertonicity-induced Activation Of Nhementioning

confidence: 93%

“…An interesting model system to investigate this are trout hepatocytes, since in these cells both RVI following cell shrinkage (Ebner et al, 2005) and the associated intracellular alkalinization (Fossat et al, 1997;Krumschnabel et al, 2003), as well as pHi recovery after acidification (Walsh, 1986;Tuominen et al, 2003) are to a large extent dependent on this ion exchanger, suggesting an important role for NHE in cell function. Furthermore, changes in cell volume as well as pHi may exert strong effects on hepatocyte metabolism (Walsh and Mommsen, 1992;Haussinger and Schliess, 1995) and therefore control of this important transporter is clearly crucial for these cells.…”

Section: Introductionmentioning

confidence: 99%

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Signalling pathways involved in hypertonicity- and acidification-induced activation of Na+/H+ exchange in trout hepatocytes

Ahmed

Pelster

Krumschnabel

2006

Journal of Experimental Biology

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SUMMARY In trout hepatocytes, hypertonicity and cytosolic acidification are known to stimulate Na+/H+ exchanger (NHE) activity, which contributes to recovery of cell volume and intracellular pH (pHi),respectively. The present study investigated the signalling mechanisms underlying NHE activation under these conditions. Exposing trout hepatocytes to cariporide, a specific inhibitor of NHE-1, decreased baseline pHi,completely blocked the hypertonicity-induced increase of pHi and reduced the hypertonicity-induced proton secretion by 80%. Changing extracellular pH (pHe)above and below normal values, and allowing cells to adjust pHi accordingly,significantly delayed alkalinization during hypertonic exposure, whereas following an acid load an enhanced pHi recovery with increasing pHe was seen. Chelating Ca2+, and thereby preventing the hypertonicity-induced increase in intracellular Ca2+ ([Ca2+]i), significantly diminished hypertonic elevation of pHi, indicating that Ca2+signalling might be involved in NHE activation. A reduction in alkalinization and proton secretion was also observed in the presence of the protein kinase A(PKA) inhibitor H-89 or the calmodulin (CaM) inhibitor calmidazolium. A complete inhibition of hypertonic- and acidification-induced changes of pHi concurrent with an increase in hypertonically induced proton efflux was seen with the protein kinase C (PKC) inhibitor chelerythrine. Recovery of pHi following sodium propionate addition was reduced by more than 60% in the presence of cariporide, was sensitive to PKA inhibition, and tended to be reduced by CaM inhibition. In conclusion, we showed that NHE-1 is the main acid secretion mechanism during hypertonicity and recovery following acid loading. In addition, Ca2+-, PKA- and CaM-dependent pathways are involved in NHE-1 activation for recovery of cell volume and pHi. On the other hand, PKC appeared to have an impact on NHE-independent pathways affecting intracellular acid-base homeostasis.

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Section: The Possible Involvement Of [Ca 2+ ]Isupporting

confidence: 84%

Section: Hypertonicity-induced Activation Of Nhementioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Signalling pathways involved in hypertonicity- and acidification-induced activation of Na+/H+ exchange in trout hepatocytes

Ahmed

Pelster

Krumschnabel

2006

Journal of Experimental Biology

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“…In trout hepatocytes, exposure of cells to NHE-specific inhibitors (Ahmed et al, 2006) or removal of extracellular Na + (Krumschnabel et al, 2003) decreased steady-state pH i and abolished the hypertonicity-induced pH i increase. Intracellularly, NHE isoforms have been reported to reside in the membranes of acidic compartments (Numata and Orlowski, 2001;Brett et al, 2002;Nakamura et al, 2005); however, an involvement of NHE activity in maintaining pH L has not been detected (Demaurex et al, 1998;Llopis et al, 1998;Schapiro and Grinstein, 2000).…”

Section: Involvement Of Na + /H + Exchangementioning

confidence: 98%

“…While the effect of cell volume changes on pH i is well documented in different cell types (Lang et al, 1998;Wehner et al, 2003) including fish cells (Walsh, 1986;Fossat et al, 1997;Furimsky et al, 2000;Krumschnabel et al, 2003), studies concerning pH L regulation in response to anisotonicity are rather pH of acid compartments few and are restricted to mammalian cells. In rat liver parenchymal cells (Volkl et al, 1994;Schreiber and Haussinger, 1995) pH L has been shown to decrease in response to hypertonicity and to increase following hypotonicity.…”

Section: Introductionmentioning

confidence: 99%

Ionic determinants of pH of acidic compartments under hypertonic conditions in trout hepatocytes

Ahmed

Pelster

2008

Journal of Experimental Biology

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SUMMARY 5 mmol l -1 ). Furthermore, hypertonicity-induced acidification was still noticeable in the presence of SITS. On the other hand, the hypertonicity-induced acidification was significantly reduced in the absence of extracellular Na + or Ca 2+ . However, BAPTA-AM induced an increase in steady-state pH L that was independent of V-ATPase inhibition. Moreover, the BAPTA-induced alkalinization was still apparent after depletion of intracellular Ca 2+ using the Ca 2+ ionophore A23187 in Ca 2+ -free medium. We conclude that pH L of trout hepatocytes is sensitive to hypertonicity and ionic determinants of hypertonicity. Thus, changes in pH L should be considered when studying pH adaptations to hypertonic stress.

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Digestive cells from Mytilus galloprovincialis show a partial regulatory volume decrease following acute hypotonic stress through mechanisms involving inorganic ions

Torre

Trischitta

Corsaro

et al. 2012

Cell Biochemistry & Function

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The response of isolated digestive cells of the digestive gland of Mytilus galloprovincialis to hypotonic shock was studied using videometric methods. The isolated cells exposed to a rapid change (from 1100 to 800 mosmol kg(-1) ) of the bathing solution osmolality swelled but thereafter underwent a regulatory volume decrease (RVD), tending to recover the original size. When the hypotonic stress was applied in the presence of quinine and glibenclamide, known inhibitors of swelling activated ion channels, the cells did not exhibit an RVD response; in addition, they showed a larger increase in size in respect to control cells. These observations suggest that the digestive cells of the digestive gland have the machinery to cope with the hyposmotic shock allowing them to exhibit a small but significant RVD preventing an excessive increase in cell size. The pharmacological treatment of digestive cells during the RVD experiments suggests that cell volume is regulated by K(+) and Cl(-) efflux followed by an obliged water efflux from the cell. The involvement of organic osmolytes such as taurine and betaine seems to be excluded by NMR measurement on digestive cells.

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Metabolic and ionic responses of trout hepatocytes to anisosmotic exposure

Abstract: exchange, suggesting an important role of these ion transporters in regulatory volume increase of trout hepatocytes.

Cited by 17 publications

References 52 publications

Signalling pathways involved in hypertonicity- and acidification-induced activation of Na+/H+ exchange in trout hepatocytes

Signalling pathways involved in hypertonicity- and acidification-induced activation of Na+/H+ exchange in trout hepatocytes

Ionic determinants of pH of acidic compartments under hypertonic conditions in trout hepatocytes

Digestive cells from Mytilus galloprovincialis show a partial regulatory volume decrease following acute hypotonic stress through mechanisms involving inorganic ions

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