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Erythrocyte deformability studied by viscometry and filtrometry
Avdelningen för klinisk fysiologi, Centrallasarettet, Växjö och Institutionen för vårdvetenskap, Vårdhögskolan i Växjö, Sverige.
1997 (Swedish)In: Nordisk kongress inom Biomedicinsk laboratorievetenskap, Lund, Sverige, 12-14 juni 1997., 1997Conference paper, (Refereed)
Abstract [en]

Abstract

 This thesis deals with factors of major importance in filtrometric studies of human erythrocytes. After an introduction in the history and background of Clinical Hemorheology in general, the importance of erythrocyte deformability as one of the determinants of flow in the microcirculation is highlighted. In a short literature review the results obtained with some methods used for measurement of erythrocyte deformability i.e. viscometry, filtrometric and micropipette techniques, are compared.

The practical part of this thesis concerns work performed with the St. George's Filtrometer and is presented in 5 separate papers ( see below). The sensitivity and reproducibility of the method are assessed. Furthermore, the influence of anticoagulants and buffer media (inclusive human plasma), the importance of filtration pressure, the possible effect of damaged and hemolysed red cells (ghosts), the influence of variations in MCV and experimentally induced changes in cell membrane function are investigated.

In a special chapter a survey is given of the factors that determine erythrocyte deformability. Besides the well known intrinsic factors ( red cell shape and size, internal viscosity, elasticity of the cell membrane), extrinsic factors as there are shear stress, vessel geometry, temperature, osmolarity, proteins, drugs, blood gasses, pH and electrolytes are discussed. Finally a study with frozen and thawed erythrocytes is reported.

The following conclusions are drawn: 

1. Red cell morphology, flow behaviour and also the reproducibility of measurements are strongly dependent on the composition of the surrounding buffer medium. Eight different buffers have been tested and of these 8 buffers, PBS buffer (phosphate buffered saline) with a small amount (i.e. 2.5 g/l) of albumin added, seems to give the most reliable measuring conditions.

2. The filtratrion pressure is an important factor in these studies. For theSt. George'sFiltrometer the optimal pressure range seems to be -30 to-50 mmH,O.

3. Differences in MCV, even within the normal range, affected passage time, flow resistance and number of clogging particles to a considerable degree, irrespective of pressure chosen. Similar differences in MCHC seems to affect these parameters less consistently.

4. Incubation of blood with ouabain caused a decrease in blood viscosity (p<0.05) compared to controls, although there was no change in red cell filterability  parameters. In contrast, filterability measurements of erythrocytes, isolated from blood incubated with calcium, indicated significantly more rigid cells, but there was no increase in blood viscosity, measured at shear rates ranging from 0.8 to 40.0 s-l.

5. Addition of hydrocortisone to blood, in vitro, resulted in a decreased whole blood viscosity (p<0.005).However, also a deteriorated erythrocyte filterability (p<0.005) was found. An increased plasma level of triglycerides and total cholesterol was noted.

6. The St. George's Filtrometer seems to have a high capacity to detect and quantify preservation injuries in frozen,thawed and deglycerolized red cells.

Parts of this thesis are reported in the literature:

-  PERSSON, S.U., LARSSON, H. Studies on red cell filterability: signifance         of buffer media. Clin Hemorheol, 11: 317-324, 1991.

-  PERSSON, S.U., HEDNER, P. Erythrocyte deformability measured by filtrometry: influence of variations in filtration pressure, MCV and MCHC. Clin Hemorheol, 13: 791-801, 1993.

- LARSSON, H., PERSSON, S.U., HEDNER, P. Changes in the functional state of the erythrocyte membrane: significance for red cell filterbility and blood viscosity. Scand J Clin Lab Invest 50: 177-181, 1990.

-  PERSSON, S.U., HEDNER, P., CANTERA, L., LARSSON, H. Effects of corticosteroids on erythrocyte filterability and blood viscosity in vitro. Clin. Hemorheol, 13: 237-243, 1993.

-  PERSSON, S.U., HEDNER, P. A filtrometric study on red blood cells after storage in frozen form. Submitted 1994.

 

Place, publisher, year, edition, pages
1997.
National Category
Medical and Health Sciences
Research subject
Natural Science, Biomedical Sciences
Identifiers
URN: urn:nbn:se:lnu:diva-11859OAI: oai:DiVA.org:lnu-11859DiVA: diva2:418575
Available from: 2011-05-23 Created: 2011-05-23 Last updated: 2011-09-20Bibliographically approved

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