Experimental evaluation of mechanical and electrical properties of RBC suspensions under flow. Role of RBC aggregating agent.

Mechanical and electrical properties of red blood cells (RBC) suspensions in dextran 70 (Dx70), dextran 150 (Dx150), dextran 500 (Dx500) and polyethileneglycol (PEG) 35,000 with different concentrations were evaluated through apparent viscosity and conductivity measurements under steady and unsteady flow conditions. RBCs suspensions of the washed RBS in PBS (control) and Dx70, Dx150, Dx500 and PEG in PBS with different concentrations, adjusted to the same hematocrit of 40% were used for the experiments. Conductivity time and shear rate dependences in parallel with the rheological properties of the samples were studied under transient flow regimes at different local structure of the uniform Couette flow. Their relationships on dextrans and PEG concentrations were evaluated too. Low shear viscosity increased and conductivity decreased of RBC suspensions, compared to non-aggregating suspensions, depending on dextrans and PEG concentrations. A time course of blood conductivity recorded under different flow conditions provides experimental description of RBC aggregation-disaggregation processes and other cell-cell interactions. The results show that the blood conductivity is strongly dependent on the considered blood factors and is influenced by flow, shear rates and concentration of dextran and PEG solutions.