Ektacytometry

Ektacytometry exposes RBC to shear stress in a Couette viscometer.  The cells are introduced between the walls of two cylinders of which one is rotating. The shear stress on the cells changes their morphology and alters a laser diffraction pattern. The shape of the diffraction pattern is directly related to the shape of the RBC and defines the laser diffraction Elongation Index (EI).  RBC deformability is dependent on several factors including membrane elasticity, surface area-to-volume ratio and intracellular viscosity.  The medium around the cells can be chosen such that it mimics the conditions experienced by RBC in the circulation. RBC can be defined in media of different osmolarity, oxygen tension of oxidative stress. 

Ektacytometry in the RBClab uses the Laser-assisted Optical Rotational Cell Analyzer (LoRRca) to define RBC deformation at different osmolarities, oxygen tensions and exposure to oxygen free radicals under shear stress.

Deformation under shear stress. The laser diffraction pattern reflects the shape of the cell. The elongation index (EI) is defined by assessment of the signal in the vertical direction (A) and the horizontal direction (B) as  EI=A-B/A+B