title: Influence of the ionic composition of fluid medium on red cell aggregation.
abstract: The effects of ionic strength and cationic valency of the fluid medium on the surface potential and dextran-induced aggregation of red blood cells (RBC's) were investigated. The zeta potential was calculated from cell mobility in a microelectrophoresis apparatus; the degree of aggregation of normal and neuraminidase-treated RBC's in dextrans (Dx 40 and Dx 80) was quantified by microscopic observation, measurement of erythrocyte sedimentation rate, and determination of low-shear viscosity. A decrease in ionic strength caused a reduction in aggregation of normal RBC's in dextrans, but had no effect on the aggregation of neuraminidase-treated RBC's. These findings reflect an increase in electrostatic repulsive force between normal RBC's by the reduction in ionic strength due to (a) a decrease in the screening of surface charge by counter-ions and (b) an increase in the thickness of the electric double layer. Divalent cations (Ca(++), Mg(++), and Ba(++)) increased aggregation of normal RBC's in dextrans, but had no effect on the aggregation of neuraminidase-treated RBC's. These effects of the divalent cations are attributable to a decrease in surface potential of normal RBC's and a shrinkage of the electric double layer. It is concluded that the surface charge of RBC's plays a significant role in cell-to-cell interactions.
mesh_terms: D001464:Barium / Q000494:pharmacology; D001799:Blood Sedimentation; D001809:Blood Viscosity; D002118:Calcium / Q000494:pharmacology; D003911:Dextrans / Q000494:pharmacology; D004586:Electrophoresis; D004594:Electrophysiology; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D009439:Neuraminidase / Q000494:pharmacology
chemical_list: D003911:Dextrans; D001464:Barium; D009439:Neuraminidase; D008274:Magnesium; D002118:Calcium