This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.105.078725v1 90/12/4720    most recent Alert me when this article is cited Alert me if a correction is posted Services 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 Kiesel, M. Articles by Sukhorukov, V. L. Search for Related Content PubMed PubMed Citation Articles by Kiesel, M. Articles by Sukhorukov, V. L.

Swelling-Activated Pathways in Human T-Lymphocytes Studied by Cell Volumetry and Electrorotation

M. Kiesel ^*, R. Reuss ^*, J. Endter ^*, D. Zimmermann , H. Zimmermann , R. Shirakashi , E. Bamberg , U. Zimmermann ^* and V. L. Sukhorukov ^*

^* Lehrstuhl für Biotechnologie, Universität Würzburg, Biozentrum, Würzburg, Germany; Abteilung für Biophysikalische Chemie, Max-Planck-Institut für Biophysik, Frankfurt, Germany; Abteilung Kryobiophysik & Kryotechnologie, Fraunhofer-Institut für Biomedizinische Technik, St. Ingbert, Germany; and Institute of Industrial Science, The University of Tokyo, Tokyo, Japan

Correspondence: Address reprint requests to Prof. Dr. Ulrich Zimmermann, Lehrstuhl für Biotechnologie, Biozentrum der Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany. Tel.: 49-0931-888-4508; Fax: 49-0931-888-4509; E-mail: zimmermann{at}biozentrum.uni-wuerzburg.de.

Small organic solutes, including sugar derivatives, amino acids, etc., contribute significantly to the osmoregulation of mammalian cells. The present study explores the mechanisms of swelling-activated membrane permeability for electrolytes and neutral carbohydrates in Jurkat cells. Electrorotation was used to analyze the relationship between the hypotonically induced changes in the electrically accessible surface area of the plasma membrane (probed by the capacitance) and its permeability to the monomeric sugar alcohol sorbitol, the disaccharide trehalose, and electrolyte. Time-resolved capacitance and volumetric measurements were performed in parallel using media of different osmolalities containing either sorbitol or trehalose as the major solute. Under mild hypotonic stress in 200 mOsm sorbitol or trehalose solutions, the cells accomplished regulatory volume decrease by releasing cytosolic electrolytes presumably through pathways activated by the swelling-mediated retraction of microvilli. This is suggested by a rapid decrease of the area-specific membrane capacitance C_m (µF/cm²). The cell membrane was impermeable to both carbohydrates in 200 mOsm media. Whereas trehalose permeability remained also very poor in 100 mOsm medium, extreme swelling of cells in a strongly hypotonic solution (100 mOsm) led to a dramatic increase in sorbitol permeability as evidenced by regulatory volume decrease inhibition. The different osmotic thresholds for activation of electrolyte release and sorbitol influx suggest the involvement of separate swelling-activated pathways. Whereas the electrolyte efflux seemed to utilize pathways preexisting in the plasma membrane, putative sorbitol channels might be inserted into the membrane from cytosolic vesicles via swelling-mediated exocytosis, as indicated by a substantial increase in the whole-cell capacitance C_C (pF) in strongly hypotonic solutions.

This article has been cited by other articles:

				V. L. Sukhorukov, J. M. Endter, D. Zimmermann, R. Shirakashi, S. Fehrmann, M. Kiesel, R. Reuss, D. Becker, R. Hedrich, E. Bamberg, et al. Mechanisms of Electrically Mediated Cytosolic Ca2+ Transients in Aequorin-Transformed Tobacco Cells Biophys. J., November 1, 2007; 93(9): 3324 - 3337. [Abstract] [Full Text] [PDF]