INVESTIGATION OF THE ENDOTHELIAL-CELL GLYCOCALYX USING ELECTROPHORESIS

The electrophoretic mobilities of bovine and porcine endothelial cells were measured by means of a light-scattering technique. Cells were ha rvested mechanically and by collagenase or trypsin digestion, and meas urements were made on both fresh and chemically fixed cells under a ra nge of solution pH, ionic strength, and composition. The effects of ad ding serum albumin to the buffer solution were also investigated. Elec trophoretic mobilities were comparable to those reported for cultured cells, and for bovine cells at pH 7.4 they ranged from -0.69 +/- .01 ( mu m/s)/(V/cm) in 0.15 M NaCl to - 2.04 +/- .08 (mu m/s)/(V/cm) in 0.0 15 M NaCl. Cells harvested mechanically had the highest mobility and t hose released by trypsin the lowest. Mobility became positive at pH 3, indicating that the glycocalyx contains more basic than sulphate grou ps. Calcium reduced the mobility at acid and neutral pH and caused cha rge reversal at high pH. In the presence of bovine serum albumin (1% w /v), mobility was reduced, demonstrating charge shielding by either ch anges in conformation of the glycocalyx or direct electrostatic intera ctions. Fixation with formaldehyde had a small, but significant effect on the electrophoretic mobility of the trypsin- and collagenase-harve sted cells.