Effect of cholesterol content in diet on capillary flow of rat erythrocytes. Part II: mechanical properties.

Erythrocytes from male Fisher 344 rats on a high cholesterol diet (HC) exhibited a decreased ability to flow through capillaries when compared with those on a normal diet (control), a phenomenon which could not be explained by changes in geometric characteristics. To explain these results, changes in capillary-dependent rheological characteristics and intrinsic mechanical properties of red blood cells (RBC) due to diet were calculated. The hematocrit deficit in the capillary with respect to the reservoir was greater in the high cholesterol diet fed rats than in the control ones. This was attributed to an overall decrease in red cell deformability which, in turn, was related to an increase in the membrane shear viscosity, the cytoplasmic viscosity, the membrane shear modulus of elasticity, and the membrane bending rigidity. By an independent calculation, we determined that the shear modulus of elasticity increased with a high cholesterol diet. The changes in both the capillary hematocrit deficit and the shear modulus of elasticity with a high cholesterol diet were found to be statistically significant (p < or = 0.05).