Viscoelasticity of whole blood as a function of age gender cigarette smoking and intake of oral contraceptives.

To assess whether the viscoelastic properties of whole blood might be influenced by age gender cigarette smoking and oral contraceptives (OCs) the authors measured viscoelasticity of whole blood and plasma at different shear rates in healthy adult subjects. 35 male and 40 female subjects were classified into 10 groups and their viscoelastic data were evaluated. Viscoelasticity of whole blood (shear rates 10/s and 50/s) viscosity of plasma (shear rate 10/s) aggregation index shear resistance and flexibility index of erythrocytes and density hematocrit were measured with an oscillating capillary rheometer and densitymeter. Age was found to increase whole blood elasticity significantly at low shear rates when young male nonsmokers were compared with old nonsmokers of both sexes. OC intake was found to increase whole blood elasticity at higher shear rates when young nonsmoking men were compared with young nonsmoking women who had taken OCs for at least 1 year. Concerning shear resistance of aggregated erythrocytes the values of young nonsmoking men were significantly lower than the values of all other groups except the group of young smoking women who had not taken OCs. Density hematocrit was higher in men than in women. Whole blood and plasma viscosities as well as aggregation and flexibility indices were not significantly different when 10 groups were compared by analysis of variance. (authors)