Method and apparatus for measuring changes in cell volume

A method of measuring change in cell volume comprising:

• introducing cells into a first chamber defined by a first pair of electrodes for measuring voltage drop across said first chamber, wherein a first chamber volume of said first chamber is between 2 and 100 times a cell volume of said cells;
• introducing a first electrically conductive extracellular fluid into said first chamber;
• applying a current through said first chamber;
• measuring voltage drop across said first chamber to obtain a first voltage drop result corresponding to said first electrically conductive extracellular fluid;
• exchanging the first electrically conductive extracellular fluid in said first chamber with a second electrically conductive extracellular fluid;
• applying a current through said first chamber;
• measuring voltage drop across said first chamber to obtain a second voltage drop result corresponding to said second electrically conductive extracellular fluid;
• using said first voltage drop result and said second voltage drop result in conjunction with known voltage drops across said first chamber for the first and second electrically conductive extracellular fluids, respectively, absent impedance to current flow attributable to said cells, to monitor changes in said cell volume, said changes in said cell volume are calculated according to:
• Δ
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• ⁢
• V
• V
• =
• Δ
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• R
• R
• SC
• ×
• 1
• R
• RC
• R
• 0
• -
• 1
• ;
• wherein V0 is a volume of said cells after introducing said first electrically conductive extracellular fluid into said first chamber,
• V is a volume of said cells after stimulation by exchanging the first electrically conductive extracellular fluid with the second electrically conductive extracellular fluid,
• ΔV=V−V0,
• Δ
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• V
• V
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• is
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• a
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• relative
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• cell
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• volume
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• change
• ,
• R0 is a first resistance correlated to the known voltage drop across said first chamber for said first electrically conductive extracellular fluid,
• RRC is a second resistance correlated to the first voltage drop result,
• RSC is a third resistance correlated to the second voltage drop result, and
• ΔR is RSC−RRC.