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The study assessed the physical characteristics of erythrocytes, viscosity and deformability, measured by a widely described double-filtration method. At the same plasma-cell viscosity was measured and the importance of the rigidity of RBC was evaluated as one of the many forces which interact among the cells and between the plasma and cells. The results showed a marked increase in corpuscular viscosity with reduced deformability, and a significant diminution of plasma-erythrocytic viscosity, whereas total viscosity remained unaltered. These parameters do not correlate with the quantitative pathological alterations of HbA2, but only with RDW-SD. Alterations of the proteic components with a relative increase in the alpha-chains of the erythrocytic membrane are thought to be responsible for these anomalies, by means af the modifications that the excess of alpha-globin causes to the structure and function of erythrocytic membrane; but the quantity of globin is not the decisive factor, and in fact the introduction of the beta-chains are able to correct erythrocytic deformability (Sorensen). Membrane rigidity is probably independent and unrelated to microcytemia, because these erythrocytes, have an excess of surface in relation to their volume, due to the simultaneous alteration of permeability. The diminished plasma-erythrocytic viscosity should be connected with the prevalence of repulsing forces, due to erythrocytic rigidity in relation to the attracting forces due to the proteic fractions which remain unchanged.

In 12 patients with acute myocardial infarction we have studied the behavior of the red blood cell filterability using polycarbonate membranes of 13 mm diameter with pores of 5 mu diameter according to the Reid's method. The samples were drawn soon afterwards the admission and successively every 48 h for a period of about 12 days. In the meantime, erythrocyte sedimentation rate (ESR), fibrinogen, leukocyte, platelet and alpha 2-macroglobulin changes have been determined. The average initial filterability values in patients with infarction were 0.84 +/- 0.20, while in control subjects were 0.58 +/- 0.15. During the observation period, a statistically significant increase of filterability after 48 h (1.06 +/- 0.24) and after 96 h (0.88 +/- 0.21) was observed. Using the statistical analysis we have noticed a strong correlation among filterability and leukocytes and ESR. The effect of leukocytes is due to the reduction of membrane pores through which red blood cells filter. The correlation with the ESR shows the presence of a plasma factor different from fibrinogen and capable of transforming the red blood cell aggregation by reducing their filterability.

We have demonstrated how conservation time affects whole blood filterability. The filtration index decay appears just after withdrawal and is present, with different characteristics, both at room temperature and at 37 or 4 degrees C. It is absolutely necessary to take measurements immediately after blood withdrawal.

The hemorheological findings obtained from a study employing an infusion of thymoxamine in saline solution and after the addition of the same drug to blood samples in vitro are reported. The hemorheological changes observed in vivo (decrease of both hematocrit and blood viscosity at shear rates of 23 and 230 sec-1) are not seen in vitro. From these data it is possible to conclude that such modifications produced by thymoxamine in vivo are more likely due to its alpha-blocking action than to a direct hemorheological activity of this drug.

In 45 diabetic patients (22 men and 23 women) subdivided in relation to type and vascular complications we have evaluated the erythrocyte filterability either by filtering whole blood (VRBC) or red blood cells suspended (5%) in autologous prefiltered plasma (deformability index). From the obtained results it is evident that VRBC is able to distinguish diabetic patients from normal subjects, whereas this does not happen with the deformability index. The explanation of these data is that the whole blood filterability, especially in diabetic patients, depends on the behavior of both cellular and plasmatic extraerythrocyte parameters.

We have determined the main hemorheological parameters in a group of patients suffering from myotonic dystrophy and in another group with oculopharyngeal or limb-girdle myopathy. From the results we have obtained it is evident that of all the rheological parameters considered only hematocrit, fibrinogen and fibrinogen/albumin ratio are different in patients with myotonic dystrophy when compared to that of normal controls. There were no variations in blood, plasma and serum viscosities and in erythrocyte filterability. In addition, hemorheological alterations were not present in patients with oculopharyngeal or limb-girdle myopathy.

The effect of different insulin concentrations on the deformability of normal red blood cells resuspended in different media was studied in vitro. Insulin enhances red blood cell deformability measured by the filtration method and the observed increases are directly correlated with insulin concentrations. When red blood cells are resuspended in plasma of diabetic patients, the red blood cell filterability through Nucleopore filters is slower than that observed by resuspending the erythrocytes in normal plasma. This suggests that the plasma of diabetic patients contains an unknown factor able to reduce red blood cell deformability.

In 17 patients affected by atherosclerotic vascular disease and showing in basal conditions a hyperviscosity state, we have monitored the main hemorheological determinants during treatment with Suloctidil. At the end of treatment carried out for 5 months the results showed that erythrocyte filterability was the only hemorheological determinant influenced. The possible causes of this action are therefore considered.

The whole blood and plasma viscosity, hematocrit and plasma fibrinogen were studied in 26 diabetic patients (11 with and 15 without retinopathy) and in 25 non-diabetic control subjects. Blood viscosity, plasma viscosity and plasma fibrinogen were significantly higher in diabetics than in controls, but no significant differences were found when diabetics with retinopathy were compared to diabetics without retinopathy. The red cell deformability was significantly reduced in diabetics if compared with that of controls; the statistical significance of this reduction was confirmed only in the group of diabetics with retinopathy, but failed when the group of diabetics without retinopathy was considered.

Plasma and red cell acid-base equilibrium was studied in 14 healthy subjects following the induction of acidosis by means of i.v. acetazolamide. It was found that changes in red cell values were significantly less marked than those in plasma.

We had intended to study the relation between glycemia and hematocrit during high altitude acclimatization (Morococha, Peru-4560 m) and to observe if, subsequently to an increase of hematocrit, glycemia should become lower. From obtained results upon 176 hematologic observations of glycemia, hematocrit, hemoglobin and erythrocyte production, on 38 healthy European subjects (27-58 years aged), it doesn't result, from the first analysis, the existence of this relation. We reserve ourselves, in any case, to accomplish further tests, such as insulinemic dosage for evaluating pancreatic activity.

The morphological and metabolic properties of red blood cells submitted to the procedure of loading by hypotonic hemolysis and isotonic resealing were compared with the controls. No appreciable differences could be detected concerning glycolytic ability, the amount of glucose metabolized in the hexose monophosphate pathway and the concentrations of glycolytic intermediates of ATP and of 2,3-DPG. Instead the concentration of reduced glutathione and the MCV were slightly reduced. These manipulated erythrocytes can be used as potential bioreactors or as carriers of exogenous substances.

The aim of our research was to investigate the effect of prostacyclin (PGI2) on red blood cell deformability and blood viscosity. Ten non-smokers healthy subjects (aged from 25 to 40) were examined. Different PGI2 concentrations were added to the blood sample and then red blood cell deformability and blood viscosity were measured: 1.2 and 2.4 ng/ml PGI2 concentrations, corresponding to plasma PGI2-like activity in man, increased red blood cell deformability and reduced blood viscosity. The PGI2 capacity of affecting red blood cell deformability and blood viscosity seems to be of clinical interest in conditions where the PGI2 production is reduced, such as ischemic heart disease, peripheral artery disease and diabetes mellitus.

The deformability of red blood cells depends not only on acidosis and hypoxia, but also on hemoglobin concentration, presence of Heinz bodies, characteristics of red blood cells, membrane fluidity, surface/volume ratio, ATP levels and water concentration of red blood cells. The two most important consequences deriving from the change in one or more of the above mentioned factors are a reduction of red blood cell flexibility and an increase of red blood cell aggregation. We have examined various drugs which directly or indirectly interfere with one or more of the previously listed factors. There are also drugs considered useful in improving the altered red blood cell deformability and/or in reducing the formation of red blood cell aggregates; among these are some xanthine derivatives (pentoxifylline) and some calcium-entry blockers used as antihistamines (cinnarizine and flunarizine). These considerations need an experimental verification based on in vitro and in vivo or ex vivo studies.

A research on hemorheological and microvascular behavior with regard to the red blood cell filterability determined by the Teitel-Reid-Dormandy technique has been performed on 15 subjects with microangiopathy due to vibrating tools, who were hospitalized at the Work Medicine Institute of the 2nd Medical Faculty of Naples University. The results pointed out an increase of filtration times and a consequent decrease of blood flow, as opposed to the control group. As a conclusion of the research, the authors were in the opinion that in the vibrating tool syndrome, in addition to the hemodynamic elements, the hemorheological components of the microcirculation should also be primarily evaluated alongside red blood cell filterability.

The authors report their study on the red blood cell deformability of 30 patients with isolated and combined obstructive lesions in both aorto-iliac and femoral trunk, performed before and after the exercise test. Such a test does not significantly change the deformability in normal patients while, on the contrary, the exercise test significantly changes the deformability in patients affected by atherosclerotic disease. Furthermore, in the experience of the authors the decrease of the deformability is directly related to the degree of the circulatory impairment.

Microspectrophotometry turns out to be the ideal method for an accurate study of single cells, namely of red blood cells, from the biochemical and physiological standpoint. Hereafter several possible applications are reported: a. the kinetics of gas-exchange (O2 and CO) in human erythrocytes has been made possible by the photosensitivity of the Hb-CO complex. In this way, it has been possible to establish that both ligands recombine with intraerythrocyte hemoglobin following a zero-order kinetic process. This suggested that diffusion of a ligand across an unstirred layer of buffer (approximately 5.10 mu thick) all around the cell could be the rate-limiting step of this recombination. Moreover, an intracellular facilitated oxygen diffusion has been observed and possible physiological implications have been shortly mentioned; b. the kinetics of intracellular polymerization of sickle cell hemoglobin in single red blood cells has been measured by quickly (approximately 1 msec) flashing-off the CO employing a cw Argon ion laser. The polymerization of deoxyhemoglobin has been followed by detecting the increased light scattering of the laser beam itself. The distribution of delay times (td) in several patients has been found significantly correlated to the severity of the disease, supporting the hypothesis that the td is a determinant factor in the pathophysiology of the disease. Possible therapeutic applications of this method are briefly discussed; c. the intraerythrocyte distribution of different hemoglobins of trout (Salmo irideus) among several erythrocytes has been observed by means of different physiochemical properties of single components. These turned out to be homogeneously present in all red blood cells studied.

Ischemic cardiopathy in its various clinical manifestations, whether acute (angina pectoris or myocardial infarction) or chronic (chronic coronary insufficiency), has shown in recent years particular hemorheological characteristics of its own. The observation of patients with such diseases has allowed us to record the existence of modifications in the parameters indicative of rheological damage. Numerous studies have been made, many of which are still in progress, with the aim of clarifying the relationships between these data and the disease. In our experience an increase in blood and plasma viscosity and a decrease in red cell deformability are often present in a manner which is statistically significant, if these patients are compared with normal subjects. Hemorheological change is more evident in the acute forms of myocardial ischemia. In fact, in angina pectoris the occurrence of pain is always accompanied by an increase in blood viscosity and by a worsening of red cell deformability both during spontaneous crises and during provocative tests. The hemorheological damage tends to diminish fairly rapidly when the crisis is over, even if the level of stabilization proves to be still higher than normal. In myocardial infarction higher levels of viscosity appear for a brief period after the onset with a slight tendency to diminish up until the 30th day. With the aim of ascertaining whether the alteration is more evident precisely at the point where the ischemia occurs, we chose a necessarily limited number of subjects, undergoing coronarography and atrial pacing for diagnostic purposes, and decided to control the hemorheological data not only in the systemic venous blood but also in the blood taken from the coronary sinus. Our data has shown that the level of viscosity and of red cell filtrability, in the blood taken from the coronary sinus, is worse than those of the systemic venous blood and that, after atrial pacing, in negative pacing subjects the variations are of slight significance whilst in positive pacing subjects we observe a rapid increase in viscosity and a decrease in red cell filtrability. This seems to confirm what we have already observed in the limbs affected by peripheral ischemia, and to demonstrate the existence of a local hyperviscosity syndrome which, even in the myocardium, appears to be dependent on the tissue ischemia.

Blood viscosity, plasma viscosity and erythrocyte filterability were studied in 46 diabetic and in 24 hyperlipidemic patients and were compared with those of a group of normal controls; 35 diabetics were type I (IDDM, 13 of whom complication-free and 22 with micro- and macroangiopathy), 11 diabetics were type II (NIDDM, 5 of whom complication-free and 6 with micro- and macroangiopathy). Erythrocyte filterability was lower in type I and II diabetes than in controls, and was also lower in diabetics with vascular complications than in complication-free patients. Erythrocyte filterability inversely correlated with HbA1c and with plasma uric acid levels. The hyperlipidemic group included 6 type IIa, 6 type IIb, 8 type IV and 4 type V patients. All hyperlipidemic patients were examined before and during diet and drug therapy. In all the hyperlipidemic patients blood viscosity inversely correlated with HDL-cholesterol, while plasma viscosity directly correlated with plasma uric acid. All these findings suggest that some hemorheological factors can play a role in the onset and progression of vascular complications of diabetes mellitus and hyperlipidemias, and that the hemorheological changes correlate with the severity of the metabolic abnormalities.

The relationship between some glucose metabolism alterations in erythrocytes and the increased rigidity of these cells in diabetes mellitus is discussed. For this purpose, the literature data concerning the role played by glycolytic intermediates, adenosine and pyridine nucleotides and by insulin are particularly analyzed. In addition, original data on intracellular levels of some sugars, in particular sorbitol and their contribution in the rise of erythrocyte rheological alterations in diabetic subjects are presented.

Differences in erythrocyte distribution on Ficoll-Sodium Metrizoate discontinuous density gradient were evaluated between adult males and females. Testosterone and androstenedione plasma levels were tested in males, oestradiol, progesterone and prolactin in both males and females. Female group showed a much higher proportion of lighter younger erythrocytes than males, while males showed higher proportion of denser older cells. Positive correlation was found between young cell percent and oestradiol level, both in males and females, but no correlation was found with androgen hormones.

Erythrocyte deformability is one of the most important factors on determining blood viscosity. Many microcirculation damages are caused by alteration of viscosity. We propose a method for evaluate erythrocyte filtration using Nucleopore membranes, to study erythrocyte deformability. Normal ranges are calculated in young healthy subjects. Mean filtration time is determined on 5 filtrations for every subject. Filtration rate is expressed by sec/ml and correlated whit haematocrit. The method is not easily utilizable, but it can be useful in the knowledge of the role of the erythrocyte deformability in the altered microcirculation.

The aim of this paper is to test whether an alteration of blood flow in microcirculation and in particular of red cell deformability is present in myocardial ischaemia. To this end we determined by the method proposed by Reid and Dormandy (J. Clin. Pharmacol. 1976, 29, 855) whole-blood filterability in 23 patients with myocardial ischaemia, in 15 clinically healthy subjects and in 99 subjects without clinical evidence of ischemic pathology displaying one or more vascular risk factors. Blood filterability turned out to be significantly lower in cases of coronary diseases than in controls (p less than 0,001), while it was lower but not significantly so, than in subjects displaying risk factors. We conclude therefore that the presence of risk factors is enough important to be considered one of the fundamental elements (though non the only one) in causing the reduction of blood-filterability encountered in ischemic cardiopathology.

A hemorheological study has been carried out in patients suffering from peripheral occlusive arterial disease alone or associated with occlusive arterial disease of the epiaortic vessels or with ischemic heart disease. Significantly more severe hemorheological impairments of whole blood viscosity, plasma viscosity and erythrocyte filterability have been observed in patients with ischemia of two vascular districts than in patients with peripheral ischemia alone.

We measured the whole blood filtration time of 30 healthy subjects. The influence of hematocrit, fibrinogen, leucocyte and platelet count on filtration time was also evaluated. Multiple regression analysis did not demonstrate any effect of the above-mentioned parameters when they were separately considered. We have subsequently taken from the entire population a group of 14 subjects in which were simultaneously found values of hematocrit greater than or equal to 41%, fibrinogen greater than or equal to 210 mg/100 ml and platelet count greater than or equal to 250,000/mm3. The filtration time was significantly higher in this group (69 +/- 4 sec) than in the remaining 16 normal subjects (56 +/- 4 sec), p less than 0.05. These data suggest that the simultaneous variation of several parameters could modify the whole blood filtration time, while these parameters have no effect when taken separately.

Our research was aimed at testing the role of the main cardiovascular risk factors in modifying the blood flow in microcirculation and in particular red cell deformability. To this end we determined by the method proposed by Reid and Dormandy (J. Clin. Pharmacol. 1976, 29, 855) whole-blood filterability in 15 smokers, 18 diabetics, 14 hypertensives, 16 dislipidemics, without clinical evidence of ischemic pathology and with negative vascular pathology anamnesis. In diabetics, hypertensives and dislipidemics blood filterability turned out to be significantly lower (p less than 0,001) that in 15 controls. In smokers it was also lower, although in a less significant way.

By means of the filterability test of Reid et al., the influence of a subpopulation of rigid erythrocytes (5% and 2.5%, respectively) was studied using Nucleopore polycarbonate membranes with pore size of 5 mu and diameter of 13 mm. The addition of 5% and 2.5% of rigid red cells delays the erythrocyte filtration times and alters the red cell deformability index. The meaning of the obtained data is discussed.

Red blood cell filtration rate was studied in patients with essential hypertension selected according to the homogeneity of parameters which could interfere with such a test. An increase of filtration time in control subjects was put in evidence both in patients without vascular complications and in patients with cerebrovascular diseases; no significant difference was seen between the two groups. The red cell filterability behavior can be correlated to hypertension and is an expression of red cell deformability alterations. The variation of this hemorheological parameter could be better defined by an improvement of the red cell filterability test and by further studies on the membrane function in essential hypertension.

It is known that a medium conditioned by erythrocytes (ECM) reduces 59Fe uptake into haem in hemopoietic cell cultures. In order to evaluate if the release of this factor in conditioned media is correlated with the whole erythrocyte surface, the same volume of packed erythrocytes of Mammals characterized by different MCV were incubated according to the method of Cole and Regan (1977). The influence of these conditioned media upon 59Fe uptake into haem in cultures of Guinea pig bone marrow cells was studied. Our results demonstrate that ECM of lamb erythrocytes (MCV = 28) caused a more marked depression of haem synthesis in vitro than ECM of calf (MCV = 34) and Guinea pig (MCV = 69) erythrocytes, and that this inhibitory effect is correlated to the MCV of considered erythrocytes.

We have demonstrated how temperature affects whole blood filterability. The filtration index appears to be dependent on temperature; the higher temperature is, the higher it rises. At body temperature of 37 degrees C the method resulted more reliable.

This study has been performed to evaluate the in vivo effect of acetylsalicylic acid (ASA) i.v. infusion at two different dosages: 500 and 2,000 mg on the main hemorheological parameters (blood viscosity and filtrability, hematocrit) and on beta-thromboglobulin (a platelet-specific protein) in patients with peripheral obliterative arterial disease, before and after an ischemic exercise. The results obtained before and 3 and 24 h after the drug administration induced us to think that platelet-specific substances released during the ischemic exercise can affect the hemorheological parameters and that ASA may be able to interfere with these reactions by inhibiting the platelet release.

Hemorheological changes were more recently believed to be responsible for the pathogenesis of the Raynaud's phenomenon. In order to verify such changes, the authors report the data on red blood cell deformability obtained from a study performed in 8 patients with cold-induced Raynaud's phenomenon. From the evaluation of these data it seems likely that hemorheological changes observed during the phenomenon are the consequence of the ischemia and not vice versa.

The red blood cell deformability was evaluated in 10 patients suffering from chronic respiratory failure and in 10 normal volunteers. Patients with chronic respiratory failure showed a pH of 7.36 +/- 0.04, a pCO2 of 48.7 +/- 7.3 mmHg and a pO2 of 61.2 +/- 10.2 mmHg and had a decreased red blood cell deformability if compared with normal volunteers (p less than 0.001). The red blood cell deformability of patients suffering from chronic respiratory failure showed a weak correlation with pO2 (r = 0.50, p less than 0.05).