Rheological properties of erythrocytes from male hypercholesterolemia Chung-Yung J. Lee, Ki-Chan Kim, Hong-Wook Park, Jin-Ho Song, and Cherl-Ho Lee * Graduate School of Biotechnology, Korea University, Seoul, Republic of Korea Received 14 July 2003 Abstract Diet and general health status has close relation to the flow behavior of blood, which influences the circulation of the blood in the body. In this study, we have compared the rheological properties of erythrocyte, plasma and whole blood from high-cholesterol male subjects with healthy male subjects. Intravenous blood was taken from healthy males (n = 10) and males with high cholesterol (n = 14). Basic health profile, BMI, hematological count and lipid profile (total cholesterol, LDL, HDL and triglyceride) of the blood were determined. Viscosity and shear rate dependent flow behavior of the subjects blood were measured by cone and plate rheometer, and permeability of erythrocytes by pulsed field gradient NMR. Using the microchannel flow analyzer (MC-FAN), the microcirculation of erythrocyte and plasma were investigated. Our data showed a difference in viscosity and consistency index of the whole blood, and permeability (P < 0.05) of erythrocytes between the two groups. Also, the time taken for the flow of erythrocyte and plasma through the MC-FAN was slower for the high- cholesterol group. Correlation study showed that consistency index of the blood is closely related to the level of LDL (P < 0.05), and total cholesterol, HDL and LDL (P < 0.01) highly correlated with the microcirculation of erythrocyte and plasma. A negative correlation (P < 0.05) was found between total cholesterol, HDL and LDL, and permeability of erythrocytes. It is concluded that high level of cholesterol, LDL and HDL in vivo alter the morphology and flow behavior of blood cells that can subsequently increase the risk of impairing physical function and microcirculation. D 2004 Elsevier Inc. All rights reserved. Keywords: MC-FAN; PFG-NMR; Hemorheology; Erythrocyte permeability Introduction Erythrocyte is the biggest group of cells found in blood. Diet and general health status has close relation to the morphological and rheological characteristic of erythrocytes (Kanakaraj and Singh, 1989). It is highly deformable and the membrane plays an important role for maintaining the flexibility for normal erythrocyte deformability. Even a small degree of membrane stretching has been proposed to cause hemolysis. Increased erythrocyte aggregation, viscos- ity, rigidity and decrease in membrane fluidity, i.e., enlarged metabolic pool of free calcium ions, have been found in hyperlipidemias. Also, in vitro loading of cholesterol to erythrocytes showed increased surface area and deformabil- ity. Apart from changes in rheological properties of eryth- rocytes, an increase in cholesterol in vivo impairs the microcirculatory system. It has been previously hypothe- sized that dietary cholesterol can alter the erythrocyte cell membrane properties (Peddada et al., 1997) and permeabil- ity, hence the transport system. Recently, Microchannel Flow Array Analyzer (MC- FAN), a micromachine that simulates the human blood capillaries, are widely used to assess the flow behavior and deformation of erythrocytes (Kikuchi et al., 1992, 1994; Sutton et al., 1997), in particular in disease models (Begum and Terao, 2002). One reason for the change in flow behavior of erythrocytes is due to alteration of the cell membrane. The measurement of self-diffusion coefficients of water and ions in biological cells and tissue can predict the functionality of the cell membrane. Pulsed Field Gradi- ent-NMR (PFG-NMR) have been applied by scientists to understand the relation of physical and biochemical prop- erties of biological cells (Suh et al., 2003; Cho et al., 2003). Due to its exceptional sensitivity to molecular displacements in the range of 10 nm to 100 Am and its (chemically) noninvasive character, such tool is valuable in the investi- gation of hematological cells in particular those related to 0026-2862/$ - see front matter D 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.mvr.2003.12.006 * Corresponding author. Graduate School of Biotechnology, Korea University, 1, 5 ka, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea. Fax: +82-2-927-5201. E-mail address: chlee@korea.ac.kr (C.-H. Lee). www.elsevier.com/locate/ymvre Microvascular Research 67 (2004) 133 – 138