Effect of time-varying stress on platelet activation.
Platelets (100 × 106/mL) from citrated blood were sheared in a cone-plate viscometer at 9600/s. Sample volumes were either 55 μL or 300 μL. Numerical analyses of this experiment are presented in panels A and B, and experimental data are depicted in panel C. (A) Distribution of local shear rates in the viscometer for the 2 sample volumes calculated based on numerical solution of the flow in this device. The average shear rate in each experiment is the same (approximately 9600/s), though the deviation from the mean is higher for the larger sample volume. (B) Mean rate of change of shear rate applied on a circulating cell/molecule is presented for the 2 sample volumes. Time-varying shear stresses are approximately 19 times greater for the larger sample volumes. (C) Increasing sample volume decreased platelet activation by approximately 30%. Data are mean ± SEM for n = 6. *P < .05 with respect to a 300 μL run.
