# Concentration or Amount ? - (Jul/27/2007 )

I have a problem imagining which one of these is right

The basic concept/question is would it make a difference cells being exposed to 5ml of a 1mg/ml growth factor (or any other drug/protein) solution compared to 1ml of a 5mg/ml growth factor solution? Both of them have 2mg of growth factor in them.

In other words is concentration of a solution more importnat than the total amout of of drug/protein in regards to effect of cells?

-SARESK-

It has something to do with the affinity of this protein to cell surface receptors. If it has high affinity, providing that the mixing is good, the difference would be less significant.

-genehunter-1-

If I were to apply it to cells, I might add 1ml of 5mg/ml solution. As adding too much of another solution can alter the media composition and might alter cell metabolism.

-scolix-

Assume the growth media compostion is the same except for both solution i.e salts, pH, amino acids. The only difference is the concentration of the growth factor in the two solutions. Would it matter then?

My instict says that the more concentrated the solution (with regards to growth factor) the bigger the expected effect - this makes sense,

But - the actual absolute amount of growth factor (although it is more dillute as its in a greater volume of media) - this also makes sense.

Which is true - I'm having a debate with my co-workers, so far its 50-50

-SARESK-

QUOTE (SARESK @ Jul 27 2007, 08:55 AM)
I have a problem imagining which one of these is right

The basic concept/question is would it make a difference cells being exposed to 5ml of a 1mg/ml growth factor (or any other drug/protein) solution compared to 1ml of a 5mg/ml growth factor solution? Both of them have 2mg of growth factor in them.

In other words is concentration of a solution more importnat than the total amout of of drug/protein in regards to effect of cells?

I thihk it will depend on in what volume of culture media you dissolve you growth factor! If volume of media is near equal to volume of your additive so it will seriously change composition of your media and will effect on your cell behavior ( due to for examle osmotic phenomenon) So in this case it will be better to use little volume of concentrated stock!

If volume of cell media exceeds more than 10 times volume of your biggest addition ( in your case 5 ml ) , so It doesn't matter because final concentration will be near the same in case of 5ml of a 1mg/ml growth factor and to 1ml of a 5mg/ml growth factor solution

-circlepoint-

the basic question is : is thje 1ml sufficent to cover your cells ?
assuming the answer is positive, i would say that effects will be stronger with 1ml of 5mg/ml. I think tha tin such experiments, the substance is not in limitative quantity, and the effect is depending of either binding to cell suface receptor / diffusion in the cell. Both are enhanced in case of igh concentrated solutions.

-fred_33-

For growth factors, its the concentration that matters.

In both cases (1mg/ml or 5mg/ml) you will have a huge excess of the growth factor over the receptor. If the growth factor has a higher concentration, it will bind more effectively (that is, if the binding site is not already saturated at 1 mg/ml).

I know, the others have already answered this question, but sometimes it needs different approaches to understand it.

Moly

-Moly-