Original Article

Pflügers Archiv

, Volume 436, Issue 6, pp 991-998

First online:

Volume changes induced by osmotic stress in freshly isolated rat hippocampal neurons

  • P. G. AitkenAffiliated withDepartment of Cell Biology, Duke University Medical Center, Box 3709, Durham, NC 27710, USA e-mail: g.somjen@cellbio.duke.edu, Fax: +1-919-6845481
  • , A. J. BorgdorffAffiliated withInstitute for Neurobiology, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands
  • , A. J. A. JutaAffiliated withInstitute for Neurobiology, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands
  • , D. P. KiehartAffiliated withDepartment of Cell Biology, Duke University Medical Center, Box 3709, Durham, NC 27710, USA e-mail: g.somjen@cellbio.duke.edu, Fax: +1-919-6845481
  • , G. G. SomjenAffiliated withDepartment of Cell Biology, Duke University Medical Center, Box 3709, Durham, NC 27710, USA e-mail: g.somjen@cellbio.duke.edu, Fax: +1-919-6845481
  • , W. J. WadmanAffiliated withInstitute for Neurobiology, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands

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Abstract

 The degree to which osmotic stress changes the volume of mammalian central neurons has not previously been determined. We isolated CA1 pyramidal cells and measured cell volume in four different ways. Extracellular osmolarity (πo) was lowered by omitting varying amounts of NaCl and raised by adding mannitol; the extremes of πo tested ranged from 134 to 396 mosm/kg. When πo was reduced, cell swelling varied widely. We distinguished three types of cells according to their response: ”yielding cells” whose volume began to increase immediately; ”delayed response cells” which swelled after a latent period of 2 min or more; and ”resistant cells” whose volume did not change during exposure to hypo-osmotic solution. When πo was raised, most cells shrank slowly, reaching minimal volume in 15–20 min. We observed neither a regulatory volume decrease nor an increase. We conclude that the water permeability of the membrane of hippocampal CA1 pyramidal neurons is low compared to that of other cell types. The mechanical support of the plasma membrane given by the cytoskeleton may contribute to the resistance to swelling and protect neurons against swelling-induced damage.

Key words Cell swelling Cell volume Cerebral oedema Dissociated neurons Hypotonia Osmotic effects