| 1. |
- Linde, Torbjörn, et al.
(författare)
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Blood viscosity and peripheral vascular resistance in patients with untreated essential hypertension
- 1993
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Ingår i: Journal of Hypertension. - 0263-6352 .- 1473-5598. ; 11:7, s. 731-736
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The viscosity of blood is increased in patients with essential hypertension. The aim of the present study was to investigate the importance of the different variables of blood rheology to total peripheral resistance, and to elucidate whether inappropriate regulation of the formation of erythropoietin could be important. DESIGN: Nineteen consecutive patients with untreated essential hypertension were examined and compared with a group of matched healthy volunteers. METHODS: The haemorheologic variables were assessed by rotational viscometry and the haemodynamic variables by bioimpedance cardiography. The serum concentrations of erythropoietin were determined by radioimmunoassay. RESULTS: The whole blood viscosity and peripheral resistance index were elevated in the hypertensive group. The two variables were positively correlated with each other (r = 0.68, P = 0.0015). The plasma viscosity and erythrocyte aggregation tendency were increased and the erythrocyte deformability, measured as fluidity, was decreased in the hypertensive patients. In the male subpopulation (n = 12) the aggregation tendency was positively, and the deformability negatively, correlated with body mass index. The serum concentrations of erythropoietin were equal in the two groups. CONCLUSIONS: The increased total peripheral resistance in patients with essential hypertension may in part be explained by an increased blood viscosity, but the possibility of an opposite cause-effect relationship must also be taken into consideration. The haemorheological abnormalities observed in the present patients cannot be explained by high serum levels of erythropoietin.
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| 2. |
- Linde, Torbjörn, et al.
(författare)
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Impaired erythrocyte fluidity during treatment of renal anaemia with erythropoietin
- 1992
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Ingår i: Journal of Internal Medicine. - 0954-6820 .- 1365-2796. ; 231:6, s. 601-606
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Tidskriftsartikel (refereegranskat)abstract
- Seventeen haemodialysis patients with renal anaemia were treated with recombinant human erythropoietin (rhEPO) and observed for 30 weeks. The viscosity of whole blood and plasma, the erythrocyte aggregation tendency, and the erythrocyte deformability, measured as fluidity, were analysed every second week. All patients responded with increasing haematocrit and whole-blood viscosity. The plasma viscosity and the erythrocyte aggregation tendency were already increased before the start of treatment, and remained unchanged during treatment. The basal erythrocyte fluidity tended to be impaired, although not significantly so. During treatment, significant impairment of fluidity was observed at the beginning of the treatment period. After 24 weeks the fluidity started to increase, and it later reached values observed before the start of treatment. Hence, the quality of the erythrocytes formed during the corrective phase of rhEPO treatment differs in some respects from that of cells formed at a normal production rate. The impaired fluidity might have important implications for the flow resistance in small vessels, and contribute to the development or aggravation of hypertension that is often seen during rhEPO treatment.
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| 3. |
- Linde, Torbjörn, et al.
(författare)
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Reduced oxygen affinity contributes to improved oxygen releasing capacityduring erythropoietin treatment of renal anaemia
- 1993
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Ingår i: Nephrology, Dialysis and Transplantation. - 0931-0509 .- 1460-2385. ; 8:6, s. 524-529
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Tidskriftsartikel (refereegranskat)abstract
- In addition to haemoglobin concentration, haemoglobin oxygen affinity plays a major role in the oxygen releasing capacity of the blood. In this study we have measured oxygen affinity as P50 and calculated the oxygen releasing capacity of blood from 10 haemodialysis patients treated with erythropoietin (rHuEpo). The patients were examined with different assays before start of treatment, after 11 weeks, and after 27 weeks. During the first phase of treatment the oxygen releasing capacity improved because of an increase in the haemoglobin concentration and P50. During the second phase there was a further significant increase in haemoglobin concentration, but due to a decrease in the P50 value the oxygen releasing capacity remained unchanged. Despite an unchanged oxygen releasing capacity and total blood volume, the antihypertensive treatment had to be increased during that phase of treatment. An increase in whole-blood viscosity may explain the increased need of antihypertensive drugs. The increase in P50 during the first phase of rHuEpo treatment can probably be explained by decreased mean age of the erythrocyte population and implies that the beneficial effect is greater than could be concluded from the increase in haemoglobin concentration.
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| 4. |
- Persson, Sylvi
(författare)
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Erythrocyte deformability studies by viscometry and filtrometry
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- DOCTORAL DISSERTATION Abstract The present thesis concerns factors of major importance in filtrometric studies of human erythrocytes, e.g. influence of buffer media, importance of filtration pressure for filtration through micropores and possible effects of damaged and hemolyzed blood cells. The reproducibility of results from haemorheological studies has also been studied. Furthermore the rheological effects on erythrocytes from experimental, functional manipulation have been studied, e.g. by adding of digitalis glycosides and corticosteroids. Finally, the rheological properties of blood, that has been stored in frozen form, have been evaluated. The first paperof this thesis shows that red cell morphology, flow behaviour and also the reproducibility of measurements are strongly dependent on the composition of the surrounding buffer medium. Paper 2points out the importance of a carefully chosen filtration pressure to make the experimental settings to come as close to the in vivo capillary circulatory conditions as possible. Influence from variations in MCV is also demonstrated in this paper. In paper 3the function of the sodium/potassium pump has, by adding of ouabain, been interfered with, thus creating changes of the intracellular ion and charge conditions. This, in turn, influences on blood viscosity. When incubating erythrocytes with calcium ions a more direct effect on erythrocyte deformability is seen. In paper 4is described the complex effect of corticosteroids on flow properties of red blood cells. Thus it is shown that the over all effect of adding a corticosteroid to a suspension of blood cells seems to be a decreased viscosity, in spite of the fact that a reduced deformability of red blood cells can be seen as a parallel phenomenon. Finally, paper 5indicates that the damage caused on red blood cells during preservation by glycerol and in frozen form may be of a haemorheological kind. Filtration through micropores seem: to be an adequate method for evaluation of damage caused to cells by freezing and parallels to the in vivo conditions in the spleen can be seen. The St George's Filtrometer, which was used in this study, seems to be able to find damaged cells in as low concentrations as 1/1000. It is concluded that a buffer solution, with a small amount of albumin added should be used in studies on filterability of red blood cells. It is also concluded that the cells are sensible to the pressure conditions used in the filtration process. A negative pressure around 30 mm H20 seems to be suitable in this type of filtration studies. Haemorheological effects of digitalis glycosides and corticosteroids are elucidated and so is the effect of blood preservation through glycerol treatment and freezing on red blood cells.
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