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At least 19 recordsLinked to original sources
PubMed1990

Influence of naftidrofuryl, a serotonergic antagonist, on erythrocyte aggregation.

Erythrocyte aggregation is an important determinant of the rheological behavior of blood and may play a critical role in nutritive tissue perfusion at the level of the microcirculation, particularly in situations of low flow. Thus, abnormal red blood cell aggregation may contribute to the pathophysiology of a variety of vascular diseases with associated microcirculatory disturbances. The action of serotonergic antagonists has a hemorheological component, although red blood cell aggregation specifically has not been addressed previously. Therefore, the effect of naftidrofuryl, a 5-hydroxytryptamine-2 receptor antagonist (5-HT2), on erythrocyte aggregation was studied in whole blood obtained from adult human volunteers. Red blood cell aggregation was measured using a Myrenne aggregometer the operation of which is based on nephelometric principles. The results demonstrate that red blood cell aggregation is significantly reduced in comparison to controls on incubation of whole blood in the presence of naftidrofuryl. This inhibitory effect is concentration dependent and reaches a maximum (approximately 30%) between 1 and 10 microM naftidrofuryl. Furthermore, naftidrofuryl (5 microM) also inhibits red blood cell aggregation in the presence of exogenously added serotonin (1 microM) on average by approximately 18%. Significant inhibition of red blood cell aggregation could not be observed in similar experiments using whole blood suspensions essentially devoid of platelets, suggesting that these blood cellular elements are involved in mediating the effects of naftidrofuryl.

Adult↗
PubMed1992

Animal species differences in erythrocyte aggregability.

Species differences in erythrocyte aggregability were investigated employing our whole blood erythrocyte aggregometer. Blood was sampled from seven species, including humans and anesthetized (30 mg/kg pentobarbital) animals. The erythrocyte aggregation rates were the following (in s-1): cats, 0.213 +/- 0.027 (means +/- SD); dogs, 0.164 +/- 0.027; men, 0.112 +/- 0.025; rats, 0.111 +/- 0.005; domestic rabbits, 0.049 +/- 0.021; and mongolian gerbils, 0.034 +/- 0.015. Domestic fowls did not exhibit erythrocyte aggregograms like those seen in the other species. Statistical analysis revealed significant differences among the erythrocyte aggregation rates of the different species (multiple-comparisons with an overall significance level of 0.05) except between men and rats and between rabbits and gerbils. No single factor which is known to accelerate the erythrocyte aggregation rate (hematocrit, fibrinogen, etc.) was correlated with the erythrocyte aggregation rate except the globulin concentration in the blood. The failure to detect erythrocyte aggregation in domestic fowls was probably attributable to their erythrocyte shape. These results suggest that each species has its own proper tendency for erythrocyte aggregation. This factor must be taken into consideration when the blood circulation is discussed among different animal species.

Animals↗
PubMed1976

The significance of plasma lipoproteins on erythrocyte aggregation and sedimentation.

Increased erythrocyte aggregation can be induced by high concentrations of human lipoproteins. The dependence of aggregate formation on lipoprotein concentration was recorded by determination of erythrocyte sedimentation rate (ESR), by electrical measurement of the erythrocyte aggregation index (EAI) and by scanning electron microscopy. The lipoprotein concentrations necessary to induce a significantly increased ESR in an otherwise normal human plasma are much too high to be encountered in physiologic or even severe pathologic states. Therefore hyperlipoproteinaemia by itself cannot explain a raised ESR. In cases where the ESR is raised due to the presence of increased amounts of other erythrocyte aggregating plasma proteins (agglomerins), hyperlipoproteinaemia can contribute to a limited extent to the increase in ESR. The possible pathophysiological significance of the demonstrated erythrocyte aggregating capacity of human lipoproteins in a microvascular environment is noted.

Blood Sedimentation↗
PubMed1978

[Erythrocyte aggregation and fibrinogen derivatives in ischemic heart disease].

Aggregation of erythrocytes was determined in 50 patients with angina pectoris and myocardial infarction and in 20 subjects of the control group by rheoscopy after Schmid-Schoenbein. It is shown that in patients with ischemic heart disease aggregation of erythrocytes is considerably increased and the hydrodynamic strength of the aggregates is greater. The erythrocyte aggregation curve is some patients with ischemic heart disease was of a biexponential character in distinction to that in subjects of the control group, which was of the monoexponential type. It was found that the increase in the strength of the erythrocyte aggregation and in the rate of aggregate formation was due to fibrinogen and its complex compounds with decomposition products.

Adult↗
PubMed1992

Nifedipine treatment in preeclampsia reverts the increased erythrocyte aggregation to normal.

OBJECTIVES: Our objectives were to assess erythrocyte aggregation in hypertensive pregnancy and to evaluate the effect of the antihypertensive treatment on it. STUDY DESIGN: The mean entity of erythrocyte aggregation was determined by an automatic aggregometer in 57 pregnant women: 20 normotensive, seven chronically hypertensive, 10 chronically hypertensive with superimposed preeclampsia, and 20 with preeclampsia. Ten of the latter were subsequently treated by 40 mg/day oral nifedipine; the other 10 by 400 mg/day oral labetalol, to keep diastolic blood pressure < 90 mm Hg. Also, patients with superimposed preeclampsia were treated with 40 mg/day oral nifedipine. RESULTS: Erythrocyte aggregation was increased in all the hypertensive pregnant patients compared with the normotensive pregnant controls, regardless of both the onset (chronic or pregnancy-induced) of hypertension and the status of plasma macromolecules. Antihypertensive treatment with labetalol significantly reduced the aggregability of erythrocytes, whereas treatment with nifedipine reverted it to normal. CONCLUSIONS: Increased erythrocyte aggregation may be due to either conformational changes of the membrane occurring during hypertension or a redistribution of the ionic charges on the two surfaces of the membrane. The effect of nifedipine by restoring the ionic charges may be due to this latter event.

Erythrocyte Aggregation↗
PubMed1976

[Thrombocyte and erythrocyte aggregation in congestive circulatory insufficiency].

In 58 patients with Stage II-III congestive circulatory insufficiency photometric techniques permitted to reveal an increased aggregation of platelets and erythrocytes. The increased erythrocytes aggregation in congestive circulatory insufficiency correlated with an increased sodium content in the erythrocytes (r = +0,82) and total body content of water (r = +0,62). The mechanisms of increased platelets and erythrocytes aggregation are discussed, as well as their role in microcirculation disorders observed in circulatory insufficiency.

Adult↗
PubMed1992

Decrease in erythrocyte glycophorin sialic acid content is associated with increased erythrocyte aggregation in human diabetes.

1. Sialic acid moieties of erythrocyte membrane glycoproteins are the principal determinants of the negative charge on the cell surface. The resultant electrostatic repulsion between the cells reduces erythrocyte aggregation and hence the low shear rate viscosity and yield stress of blood. 2. Using g.c.-m.s., a decrease in sialic acid content has been observed in the major erythrocyte membrane glycoprotein, glycophorin A, obtained from nine diabetic patients compared with that from seven normal control subjects [median (range): 3.30 (0.01-11.90) versus 18.60 (3.20-32.60) micrograms/100 micrograms of protein, P less than 0.02]. 3. Erythrocyte aggregation, measured by viscometry as the ratio of suspension viscosity to supernatant viscosity (LS/S) in fibrinogen solution, was increased in ten diabetic patients compared with ten normal control subjects (mean +/- SEM, 37.6 +/- 1.3 versus 33.8 +/- 0.6, P less than 0.02). 4. In the patients in whom both viscometry and carbohydrate analysis were performed, the decrease in erythrocyte glycophorin sialylation and the increase in erythrocyte aggregation in fibrinogen solution were related statistically (LS/S correlated negatively with glycophorin sialic acid content, r = 0.73, P less than 0.05). 5. Decreased glycophorin sialylation provides an explanation at the molecular level for increased erythrocyte aggregation and it may be important in the pathogenesis of vascular disease in diabetes.

Adult↗
PubMed1991

Erythrocyte aggregation: bridging by macromolecules and electrostatic repulsion by sialic acid.

Relation between aggregating force (of fibrinogen and IgG) and disaggregating force (due to electrostatic repulsion among erythrocytes) in erythrocyte aggregation was investigated with a rheoscope combining a video camera, an image analyzer and a computer. (i) Erythrocyte aggregation was augmented with the increase of molecular weight of bridging macromolecules as far as examined for fibrinogen and the degradation products and IgG and the related macromolecules, and the augmentation seemed to be dependent on the molecular length of macromolecules. In accelerating the erythrocyte aggregation, fibrinogen was more effective than IgG, and some interaction between fibrinogen and IgG in their coexistence was suggested. (ii) The decrease of sialic acid content on the erythrocyte surface accelerated IgG-induced erythrocyte aggregation much greater than fibrinogen-induced one. (iii) Counteraction between aggregating force and disaggregating force in leading to erythrocyte aggregation was discussed relating to molecular length of bridging macromolecule and electrostatic repulsive force by sialic acid.

Adult↗
PubMedDate not supplied

A study on the erythrocyte aggregating properties of polybrene and protamine sulphate.

By observing the aggregation of erythrocytes in protamine sulphate or Polybrene it is possible to predict MN phenotypes with 97 per cent accuracy. It is probable that one factor influencing aggregation is the relative site density of a receptor common to both M and N antigen structures although other nondiscriminating receptor sites on a lower layer of sialic acid are possible also involved.

Acetylation↗
PubMed1977

[Joint action of protein-chondroitin-4-keratan-sulfate and hyaluronic acid on erythrocyte aggregation and adhesion].

It was shown that the rate and the degree of erythrocytes aggregation brought about by a mixture of protein-chondroitin-4-keratan sulfate (PCKS) and hyaluronic acid (HA) was greater than the sum of the values of the corresponding indices observed during separate independent action of these proteoglycans on the aggregation of the mentioned cells concentrations as in the mixtures. It may be supposed that such phenomenon is connected with formation in the mixture of a hybrid PCKS-HA complex which is more active in respect to the erythrocyte aggregation than its components separately.

Cell Adhesion↗
PubMed1977

[Role of glycosaminoglycans and proteoglycans in erythrocyte aggregation and adhesion].

The action of hyaluronate potassium (HUK) and of protein chondroitin-4-sulphate potassium (PCHSK) on the aggregation and adhesion of rabbit erythrocytes suspended in physiological saline was studied. It was found that the capacity of HUK and PCHSK to produce an unspecific and reversible aggregation of erythrocytes was connected with the formation by these biopolymeres (in solutions) of complex structures of osmotic cell type and molecular sieves, displacing cells from the space occupied by them and concentrating them in a maximally limited volume. Different heparin fractions producing no such structures in solutions did not induce formation of such individual clear-cut erythrocyte-aggregations, but inhibited the aggregating action of HUK and PCHSK when the concentration of these biopolymeres were inadequate for the complete erythrocyte aggregation. Probably, the aggregating action of HUK and PCHSK necessary for adhesion served as one of the universal biological functions expressed not only towards the erythrocytes, but also towards the other cells and different tissue structural elements.

Animals↗
PubMed1992

Influence of erythrocyte aggregability and plasma fibrinogen concentration on CBF with aging.

The influence of the rheological properties of the blood on cerebral perfusion is still unresolved. Data on normal subjects are lacking and difficulties arise regarding the effect of blood viscosity owing to its close relationship with hematocrit. For these reasons we have studied the relationship between two rheological hematocrit-independent parameters and CBF in normal subjects of various ages. 36 normal volunteers, aged 20-74, free from risk factors, have been studied. CBF was measured by the Xenon inhalation method. Erythrocyte aggregability was expressed as Mean Erythrocyte Aggregation Index (MEA). Plasma fibrinogen concentration was evaluated by the coagulative method in 26 subjects. No correlation was found between CBF and MEA or fibrinogen in the subjects under the age of 45. A significant negative correlation was found between CBF and MEA (p = 0.015) and between CBF and fibrinogen (p = 0.011) in the subjects over 45. These data show that cerebral perfusion is influenced by the rheological properties of the microcirulation only with aging. We suggest that a "rheological autoregulation" exists and that it works properly in youth, only to be lost with physiological aging. This finding can be of significance in the pathogenesis of cerebrovascular disease processes in humans.

Adult↗
PubMed1992

[Increase of erythrocyte aggregation in hypertensive men with dyslipidemia].

We have already reported that erythrocyte aggregation (EA) is increased in hypertensive subjects. To study the influence of other risk factors in EA, we have measured aggregation index IA and disaggregation shear rate threshold (gamma c) by a laser technique and the biochemical parameters in 16 normotensive normocholesterolemic subjects (NT/NCT) and 45 hypertensive subjects where 17 were normocholesterolemic (HT/NCT), 18 were pure hypercholesterolemic (HT/HCTIIa) and 10 were hypercholesterolemic hypertriglyceridemic (HT/HCTIIb). The results show that IA and gamma c are more important in HT/NCT than NT/NCT patients and much more in patients with hypercholesterolemia and hypertriglyceridemia. The cumulative effects of hypertension and hyperlipidemia merit take into consideration in pathophysiology of cardiovascular complications and could help to new strategy therapeutic developments for treatment of these complications.

Adult↗
PubMed1992

[Erythrocyte aggregation and clinical course stages of venous insufficiency of the legs].

A double vicious circle at the venule and capillary level had already been pointed out by J. Dormandy and G. Nash as a pathophysiologic mechanism of rheological disorders associated with venous insufficiency of the lower limbs. Afterwards, such disorders were found by many authors when ex vivo analysis were performed on venous insufficient patients. However the time of their onset and their evolution in the course of the disease remain unknown. We studied red cell aggregation and plasma fibrinogen in 67 patients depending on the evolutive stage: 1st stage: isolated functional disorders, 2nd stage: trunk varicose vein linked to ostial incompetence, 3rd stage: trunk varicose vein linked to ostial incompetence with chronic trophic skin changes. The results showed that red cell aggregation and fibrinogen values are increased with the severity of the diseases. The rheological parameters increase when compared to controls from the first stage. Within the studied population, we avoided skewed results due to age and fibrinogen level by covariance analysis. Therefore recorded differences were practically linked with erythrocyte aggregability. Thus, red cell aggregation appears to be both an aggravating factor and a severity marker of the disease, proving the relevance of a rheological treatment in the lower limb insufficiency.

Adult↗