Pjh. Bronkhorst et al., MEASUREMENT OF RED-CELL DEFORMABILITY IN PLASMA COMPARED WITH BUFFER AS SUSPENDING MEDIUM, Clinical hemorheology, 16(2), 1996, pp. 151-163
Measurements of red cell deformability are usually performed in isoton
ic buffer solutions as suspending medium. However, in vivo, red cells
are surrounded by plasma in which plasma proteins are present. In this
study we investigated whether using plasma (anticoagulated with 1/10
vol. 110 mM trisodium citrate) instead of buffer (phosphate buffered s
aline solution) as the suspending medium gives rise to differences in
the measured red cell deformability parameters. We used ektacytometry,
the micropipette, the flow channel (both static and dynamic), and a C
ell Transit Analyzer to study this effect. Where necessary, we added 1
g/l bovine serum albumin to prevent echinocyte formation, and poly-vi
nyl-pyrrolidone to increase the buffer viscosity to match that of plas
ma. Plasma was found to be a good alternative for buffer as suspending
medium except for ektacytometric measurements. In ektacytometry, inte
ractions between plasma components and the polymer added to increase t
he medium viscosity caused measurement artefacts. Comparison between t
he plasma and the buffer measurements using the other techniques showe
d a decreased red cell deformability in plasma. We found that in plasm
a membrane elasticity is decreased and membrane viscosity is increased
compared with buffer (from micropipette and flow channel measurements
) and a decreased filterability in plasma with the Cell Transit Analyz
er. It is unclear whether the plasma composition or the buffer composi
tion is responsible for the observed increased membrane viscosity and
decreased membrane elasticity in plasma or, in other words, the decrea
sed viscosity and increased elasticity in buffer. However, our results
raise the question whether buffer is a good medium and whether deform
ability studies in general should be performed in plasma instead of in
buffer.