World Library  
Flag as Inappropriate
Email this Article

Erythrocyte aggregation

Article Id: WHEBN0026197435
Reproduction Date:

Title: Erythrocyte aggregation  
Author: World Heritage Encyclopedia
Language: English
Subject: Blood viscosity
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Erythrocyte aggregation

Erythrocyte aggregation is the reversible clumping of these cells under low shear forces or at stasis. Erythrocytes aggregate in a special way, forming rouleaux. Rouleaux are stacks of erythrocytes which form because of the unique discoid shape of the cells in vertebrate body. The flat surface of the discoid RBCs give them a large surface area to make contact and stick to each other; thus, forming a rouleaux. Rouleaux formation takes place only in suspensions of RBC containing high-molecular, fibrilar proteins or polymers in the suspending medium. The most important protein causing rouleaux formation in plasma is fibrinogen. RBC suspended in simple salt solutions do not form rouleaux.[1][2][3]

Mechanism

Erythrocyte aggregation is a physiological phenomenon that takes places in normal blood under low-flow conditions or at stasis. The presence or increased concentrations of acute phase proteins, particularly fibrinogen, results in enhanced erythrocyte aggregation.

Current experimental and theoretical evidence supports the mechanism related to the depletion of high-molecular weight molecules (e.g., fibrinogen) for rouleau formation.[4] This mechanism is also known as “chemiosmotic hypothesis” for aggregation.[5] Erythrocyte aggregation is determined by both suspending phase (blood plasma) and cellular properties. Surface properties of erythrocytes, such as surface charge density strongly influence the extent and time course of aggregation.

Effects

Erythrocyte aggregation is the main determinant of blood viscosity at low shear rate. Rouleau formation also determines Erythrocyte sedimentation rate which is a non-specific indicator of the presence of disease.[6]

Influence of erythrocyte aggregation on in vivo blood flow is still a controversial issue.[7] Enhanced aggregation affects venous hemodynamics.[8] Erythrocyte aggregation also affects hemodynamic mechanisms in microcirculation and vascular control mechanisms.[9]

Causes

Conditions which cause increased rouleaux formation include infections, inflammatory and connective tissue disorders, and cancers. It also occurs in diabetes mellitus and is one of the causative factors for microvascular occlusion in diabetic retinopathy.

Erythrocyte sedimentation rate closely reflects the extent of aggregation, therefore can be used as a measure of aggregation. Erythroyte aggregation can also be quantitated by monitoring optical properties of blood during the time course of aggregation process.[10]

Measurement

blood film

syllectometry

intravital microscopy

high-frequency ultrasound

Optical coherence tomography

References

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.