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The TL;DR version

Is there a fast way to determine what the cell environment of a particular cell (E.g RBC) is? (in terms of solute/ionic concentration)


I'm not sure if the question belongs here, but hear me out. I was doing revision and I kept coming across the line "put the cell in a solution which has the same solute/ionic concentration to prevent the cell from bursting or shrinking"

I get that concept, basically it's sort of replicating the internal environment of the cell with the buffer/solution so that the cell feels "at home."

Then my question is, how does one go about finding out how much exactly for each cell? I would think different cells have different internal environments and I don't believe that scientists actually just have stock solutions of buffers ranging from 0.00001M to 100M and trying every single solution until they find the perfect concentration.

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  • $\begingroup$ patch clamping is how it's done.also enriching the fraction you want to study, losing the cells and measuring conductivity would work $\endgroup$ – rhill45 Sep 11 '14 at 19:44
  • $\begingroup$ @rhill45 how does one "enrich" a fraction? $\endgroup$ – Nick Sep 12 '14 at 3:59
  • $\begingroup$ In this case you would want a cytosolic fraction: 1. Was cells well in pbs, pellet at low speed, sonicate at lowest setting to break membrane only, add wAter to dilute. Spin at 80,000 x g 4c fixed angle. The top fraction should be your cytosol. All measurements times 2 since you diluted in water once $\endgroup$ – rhill45 Sep 12 '14 at 4:30
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In fact the line that you quote doesn't mean that the solution is formulated to be identical to the cytosol. All that it means is that the solution should be buffered to physiological pH (typically slightly alkaline); should contain a relatively high concentration of sodium ions and a low concentration of potassium ions; and should be isotonic (i.e have the same osmolarity as the cytosol) to avoid osmotic effects such as plasmolysis (shrinkage due to loss of water) or osmotic lysis (bursting due to uptake of water).

There are many such solutions, but a commonly used simple one is phosphate buffered saline. Another is Ringer's solution. If the aim is to keep the cells metabolically active these are often supplemented with glucose or lactate, depending upon the cell type.

Addendum in response to comment from OP

According to the WP entry for Ringer's solution, Sydney Ringer determined the requirement for Na, K and Ca salts in a specific proportion when carrying out experiments with perfused frog hearts. This was in the late 19th century. A Google search measurement of intracellular ion concentrations reveals current methods.

This review starts off with a discussion of early measurements of intracellular pH (see page 298). Basically these all consisted of making cell lysates, with various attempts to prevent post-lytic changes. If you do a Google search determination of intracellular pH you will find lots of current methods.

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  • $\begingroup$ as in how did scientists derive that- what sort of tests did they do? $\endgroup$ – Nick Sep 11 '14 at 15:29
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Patch clamping

Or

Ultracentrifugation to get soluble fractions. If you get enough of it and u have validated its purity you could runs conductivity probe into your fraction

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