Cell volume changes in filtration studies of red cell deformability

Abstract

We observed significant cell swelling in the Ringer's and tris based suspension media which can interfere with filtration studies of red cell deformability. Mean corpuscular volume (MCV) in Ringer's solution increased from 95.6±2.5 fl to 109.2±2.5 fl (N=5,P<0.001) and from 95.4 fl±3.4 fl to 109.9±2.5 fl (N=5,P<0.005) in tris-saline within 2 hours of preparation of the cell suspension. These alterations in cell volume were sufficient to cause significant increases in filtration time when using 3.0 um polycarbonate filters. At 30 mm Hg pressure gradient, Ringer's suspensions showed a three-fold increase in filtration time from 11.48±1.6 sec to 32.71±6.8 sec (N=5,P<0.002), and in tris-saline, there was a six-fold increase in filtration time from 11.22±0.58 sec to 72.0±14.0 sec (N=5,P<0.001). At 45 mm Hg, in Ringer's suspensions, filtration time increased from 9.03±1.40 sec to 19.48±1.31 sec (N=5,P<0.001). These increases occured independent of hemolysis. Spontaneous cell swelling was prevented by using suspensions prepared with magnesium chloride and phosphate buffered saline. These experiments reveal that spurious changes in cell volume occur during filtration experiments using Ringer's and tris based suspension media and can confound the interpretation of deformability studies.