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Calcium and regulated volume decrease in Atlantic salmon and American alligator erythrocytes
Author(s) -
Light Douglas B,
Spivak Alina,
Pore Shruti,
Wormser Chloe,
Helm Ethan
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a964-d
Subject(s) - extracellular , egta , calcium , biophysics , chemistry , cytosol , tonicity , intracellular , biochemistry , microbiology and biotechnology , biology , enzyme , organic chemistry
A cell’s ability to regulate its volume is a property that has been conserved in a diversity of cell types; however, the mechanisms by which this compensation operates are not clearly understood. The goal of this study was to elucidate the role of Ca 2+ in regulated volume recovery (RVD) in Atlantic salmon and American alligator erythrocytes. Mean cell volume was determined by electronic sizing using a Coulter counter, and changes in intracellular Ca 2+ concentration were visualized using fluorescence microscopy and fluo‐4. Hypotonic shock led to an increase in cytosolic Ca 2+ in salmon. This increase resulted from Ca 2+ influx because it was not observed in cells bathed in a hypotonic, low Ca 2+ medium (10 nM, buffered with EGTA). Furthermore, cells of both species exposed to a low Ca 2+ environment failed to recover from cell swelling, indicating that extracellular Ca 2+ was needed for RVD. Interestingly, the Ca 2+ ionophore A23187 inhibited RVD in Na‐Ringer and when Na + was replaced with NMDG + , indicating this inhibition was not due to Na + influx. Further, although the Ca 2+ channel antagonists gadolinium and lanthanum inhibited RVD in alligator, they enhanced volume recovery in salmon. Finally, pilot studies with hexokinase and ONO‐RS‐082 suggest that RVD in alligator depends on the activation of P2 receptors and the formation of arachidonic acid, respectively. In conclusion, our results indicate extracellular Ca 2+ is necessary for RVD in both species. Future studies will examine how Ca 2+ elicits volume recovery. (Supported by Lake Forest College.)