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(Hypertension. 1998;32:324-330.)
© 1998 American Heart Association, Inc.

Scientific Contributions

Erythrocyte Disaggregation Shear Stress, Sialic Acid, and Cell Aging in Humans

Alexandra L. Hadengue; Muriel Del-Pino; Alain Simon; ; Jaime Levenson

From the Centre de Médecine Préventive Cardio-Vasculaire and Institut National de la Santé et de la Recherche Médicale (CRI-INSERM), Hôpital Broussais, Paris, France.

Correspondence to Dr Jaime Levenson, Centre de Médecine Préventive Cardio-Vasculaire, Hôpital Broussais, 96 rue Didot, 75674 Paris, Cedex 14, France. E-mail levenso{at}worldnet.sec.fr

Abstract—Erythrocyte aggregation, which plays an important role in the physiological behavior of blood fluidity, was found to be enhanced in hypertension and hypercholesterolemia. While the role of macromolecule bridging force has been widely described, cellular factors related to membrane sialic acid content, which might contribute to the negative charge of cell surface causing the repulsion of erythrocytes, have been less studied. Cell age–dependent changes in membrane sialic acid content (in micromoles per gram of integral membrane protein) were investigated in 24 normotensive and 24 hypertensive matched subjects, each divided into 2 identical subgroups according to a cutoff of 6.2 mmol/L serum cholesterol. A progressive and significant (P<0.001) decrease in membrane sialic acid content associated with an increase (P<0.001) of disaggregation shear rate threshold (laser reflectometry in the presence of dextran) were observed with increased erythrocyte density (erythrocytes fractionated by density using ultracentrifugation) in both normotensive and hypertensive groups regardless of the cholesterol level. However, disaggregation shear rate threshold was significantly higher and sialic acid content was lower (P<0.001) in both hypertensive and normotensive subjects with hypercholesterolemia compared with either normotensive or hypertensive subjects with low cholesterol, respectively. A high membrane sialic acid content variance, beginning in the younger erythrocytes, was due mainly to triglyceride and LDL cholesterol levels (R²=0.49 for low, R²=0.43 for middle, and R²=0.54 for high densities, ie, young, mean, and senescent erythrocytes, respectively). We conclude that an early decrease in erythrocyte sialic acid content may influence the rheological properties of blood by increasing the adhesive energy of erythrocyte aggregates.

Key Words: erythrocyte aggregation • rheology • sialic acid • hypertension, essential • hypercholesterolemia