QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Krumschnabel, G. Articles by Schwarzbaum, P. J. Search for Related Content PubMed PubMed Citation Articles by Krumschnabel, G. Articles by Schwarzbaum, P. J. Social Bookmarking                         What's this?

The Journal of Experimental Biology 206, 1799-1808 (2003)
doi: 10.1242/jeb.00370

Metabolic and ionic responses of trout hepatocytes to anisosmotic exposure

Gerhard Krumschnabel^1,*, Ronald Gstir¹, Claudia Manzl¹, Caroline Prem¹, Diego Pafundo² and Pablo J. Schwarzbaum²

¹ Institut für Zoologie und Limnologie, Abteilung für Ökophysiologie, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
² Instituto de Química y Fisicoquímica Biológicas (Facultad de Farmacia y Bioquímica), Universidad de Buenos Aires, C1113AAD Buenos Aires, Argentina

^* Author for correspondence (e-mail: gerhard.krumschnabel{at}uibk.ac.at)

Accepted 12 March 2003

Trout hepatocytes exposed to hypo- or hyperosmotic conditions respond by swelling and shrinking, respectively, followed by regulatory volume changes that almost, although not completely, restore cell volume. These anisosmotic conditions have a significant impact on metabolic functions. In hyposmotic medium, oxygen consumption (_O2) and glucose production rates were significantly reduced, whereas lactate accumulation was not significantly affected. By contrast, hyperosmotic conditions did not affect _O2 and lactate production but caused a sustained reduction in glucose production. Volume changes were also accompanied by alterations in intracellular free calcium ([Ca²⁺]_i). At the cell population level, hyposmotic exposure evoked a moderate and slowly developing increase in [Ca²⁺]_i, whereas hyperosmolarity caused a pronounced and sustained increase, which peaked at the time of maximum cell shrinkage but clearly exceeded a mere concentration effect due to volume reduction. Responses of individual cells were highly variable in hyposmotic medium, with only 60% showing a clear increase in [Ca²⁺]_i, while in hyperosmotic conditions all cells displayed elevated [Ca²⁺]_i levels. A decrease in intracellular pH (pHi) observed in hyposmotic medium was insensitive to EIPA, an inhibitor of Na⁺/H⁺ exchange, and SITS, an inhibitor of Cl^–/HCO₃^– exchange, but was prevented in Cl^–-free medium. In hyperosmotic medium, pHi increased. This alkalinization did not occur under conditions of blocked Na⁺/H⁺ exchange and was significantly diminished upon inhibition of Cl^–/HCO₃^– exchange, suggesting an important role of these ion transporters in regulatory volume increase of trout hepatocytes.

Key words: rainbow trout, Oncorhynchus mykiss, hepatocyte, cell volume, oxygen consumption, intracellular free calcium, intracellular pH.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				K. H. Ahmed and B. Pelster Ionic determinants of pH of acidic compartments under hypertonic conditions in trout hepatocytes J. Exp. Biol., October 15, 2008; 211(20): 3306 - 3314. [Abstract] [Full Text] [PDF]

				K. H. Ahmed and B. Pelster Interdependence of Ca2+ and proton movements in trout hepatocytes J. Exp. Biol., October 1, 2007; 210(19): 3473 - 3483. [Abstract] [Full Text] [PDF]

				S.-Z. Li, B. W. McDill, P. A. Kovach, L. Ding, W. Y. Go, S. N. Ho, and F. Chen Calcineurin-NFATc signaling pathway regulates AQP2 expression in response to calcium signals and osmotic stress Am J Physiol Cell Physiol, May 1, 2007; 292(5): C1606 - C1616. [Abstract] [Full Text] [PDF]

				K. H. Ahmed, B. Pelster, and G. Krumschnabel Signalling pathways involved in hypertonicity- and acidification-induced activation of Na+/H+ exchange in trout hepatocytes J. Exp. Biol., August 15, 2006; 209(16): 3101 - 3113. [Abstract] [Full Text] [PDF]

				H. L. Ebner, A. Cordas, D. E. Pafundo, P. J. Schwarzbaum, B. Pelster, and G. Krumschnabel Importance of cytoskeletal elements in volume regulatory responses of trout hepatocytes Am J Physiol Regulatory Integrative Comp Physiol, September 1, 2005; 289(3): R877 - R890. [Abstract] [Full Text] [PDF]

				D. E. Pafundo, P. Mut, M. Perez Recalde, R. M. Gonzalez-Lebrero, V. Fachino, G. Krumschnabel, and P. J. Schwarzbaum Effects of extracellular nucleotides and their hydrolysis products on regulatory volume decrease of trout hepatocytes Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2004; 287(4): R833 - R843. [Abstract] [Full Text] [PDF]