Blood is settling

Deitiker, Philip R via (by pdeitik from
Thu Jul 29 15:03:46 EST 2010

Red blood cell sedimentation occurs in mildly dilute aqueous fluid or if allowed to stand more than a few hours even when anti-coagulants are used (Excessive dilution of RBCs in water causes them to lyse. 
You can effectively prevent sedimentation by using a high molecular weight or dense solute (such as cesium chloride, glycerine, or sucrose) therefore increasing the specific gravity of the solution. Glycerine is probably the least destructive but has the lowest specific gravity. Try adding 5% to 10% glycerine to the solution. Note: glycerine also increases the viscosity of the solution and therefore slows the rate of diffusion, at 5 to 10% not much of an increase. With higher percentages one will observe an 'astronomical' increase in viscosity. Probably the safest approach for short term analysis (but very expensive) is to use D2O - deuterated water), D2O may eventually equilibrate inside the RBCs and they will settle.  

-----Original Message-----
From: methods-bounces from [mailto:methods-bounces from] On Behalf Of Joshua Silverstein
Sent: Thursday, July 29, 2010 10:10 AM
To: methods from
Subject: Blood is settling

Hi again -

I'm running blood over some surfaces under flow with a syringe pump.  The
problem is that the blood seems to settle extremely quickly when it is on
it's side in the pump.  A colleague suggested putting a stir bar inside the
syringe but I am worried about activating the platelets and since the
primary objective of this experiment is to assess platelet adhesion, I don't
know if that's a good idea.  Any other suggestions or at least a maximum
speed so that I do not skew the results?

Josh Silverstein
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