Modulation of density-fractionated RBC deformability by nitric oxide

The role of nitric oxide (NO) in maintaining normal mechanical behavior of red blood cell (RBC) has been previously demonstrated. The effects of NO donor and NOS inhibitor on the mechanical properties of density fractionated RBC were tested in this study. A non-specific NOS inhibitor, N-omega-nitro-L-arginine methyl ester (L-NAME) at a concentration of 10-3 M and sodium nitroprusside (SNP), a nitric oxide donor at a concentration of 10-6 M was added to blood samples with hematocrit adjusted to 0.4 l/l and RBC deformability was measured by an ektacytometer in the density fractionated RBC after one hour incubation at 37°C. There was no significant effect of the NO donor SNP on cellular deformability in the older (denser) RBC fraction in contrast with the younger (least dense) fraction. Alternatively, the sensitivity of cellular deformability to competitive NOS inhibition by L-NAME was greater in the older fraction. These findings suggest that older RBC are characterized by diminished internal NO synthesis and are also less sensitive to external NO indicating that the target mechanisms for NO may also be deteriorated. © 2005 - IOS Press and the authors. All rights reserved

Photometric measurements of red blood cell aggregation: light transmission versus light reflectance

Red blood cell (RBC) aggregation is the reversible and regular clumping in the presence of certain macromolecules. This is a clinically important phenomenon, being significantly enhanced in the presence of acute phase reactants (e. g., fibrinogen). Both light reflection (LR) and light transmission (LT) from or through thin layers of RBC suspensions during the process of aggregation are accepted to reflect the time course of aggregation. It has been recognized that the time courses of LR and LT might be different from each other. We aim to compare the RBC aggregation measurements based on simultaneous recordings of LR and LT. The results indicate that LR during RBC aggregation is characterized by a faster time course compared to simultaneously recorded LT. This difference in time course of LR and LT is reflected in the calculated parameters reflecting the overall extent and kinetics of RBC aggregation. Additionally, the power of parameters calculated using LR and LT time courses in detecting a given difference in aggregation are significantly different from each other. These differences should be taken into account in selecting the appropriate calculated parameters for analyzing LR or LT time courses for the assessment of RBC aggregation. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3251050