title: Estimation of viscous dissipation inside an erythrocyte during aspirational entry into a micropipette.
abstract: Viscous dissipation inside the erythrocyte during its aspirational entry into a micropipette is analyzed. The motion of the intracellular fluid is approximated by a flow into the micropipette orifice from a half space (the portion of the erythrocyte outside the micropipette). The stream function and intracellular pressure (p) in the half space are obtained as a function of radial and axial positions near the orifice. Solution of the boundary value problem for a uniform stream entering a circular hole gives p = 2 eta HQ/pi R3p, where eta H is the intracellular viscosity, Q is the total discharge, and Rp is the pipette radius. The results indicate that the moving erythrocyte membrane helps to drive the intracellular fluid into the orifice. For normal erythrocytes, p is only approximately 0.5% of the total aspiration pressure (delta P). The contribution of p to delta P, however, may become significant when there is a large increase in eta H due to a markedly elevated intracellular hemoglobin concentration or an alteration of the physical state of hemoglobin.
mesh_terms: D000818:Animals; D001800:Blood Specimen Collection; D001826:Body Fluids / Q000502:physiology*; D004910:Erythrocyte Membrane / Q000502:physiology; D004912:Erythrocytes / Q000502:physiology*; D007424:Intracellular Fluid / Q000502:physiology*; D008433:Mathematics; D008954:Models, Biological; D014783:Viscosity