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PubMed1989

Viscous resistance to blood flow in solid tumors: effect of hematocrit on intratumor blood viscosity.

Blood flow rate in a vascular network is proportional to the arteriovenous pressure difference and inversely proportional to the geometric and viscous resistances. We have recently shown that the geometric resistance to blood flow increases with increasing tumor size and/or decreasing arterial pressure. In this study, the viscous resistance to blood flow within tumor microvasculature was determined by alternately perfusing mammary adenocarcinoma [R3230AC; N = 12; tumor weight, 2.2 +/- 1.6 (SD) g] ex vivo with Krebs-Henseleit solution and with RBC suspensions at hematocrits between 1 and 60%. Our results demonstrate that: (a) intratumor blood viscosity increases with increasing hematocrit; and (b) for fixed hematocrits between 10 and 60%, the intratumor blood viscosity is significantly reduced (P less than 0.0001) compared to bulk viscosity measured at shear rates of 460 s-1 using a cone/plate viscometer. However, this reduction of intratumor blood viscosity is not as pronounced as in a previous study of skeletal muscle. Further comparison shows that as arterial pressure is lowered, intratumor blood viscosity increases at a greater rate and at lower hematocrits than in normal tissues. We attribute the increased viscous resistance in tumor microvasculature to (a) a less pronounced Fahraeus effect (i.e., reduction in hematocrit in small vessels) and a less pronounced Fahraeus-Lindqvist effect (i.e., reduction in blood viscosity in small vessels) in dilated tumor microvessels compared to normal microvessels; (b) low shear rates (i.e., velocity gradients) associated with tumor vessels which may facilitate rouleaux formation at moderate pressures and even at low hematocrits; and (c) vascular fluid losses of 5-14% which may also increase microvessel hematocrit. We also propose that intratumor blood viscosity may be even higher in vivo than ex vivo due to the presence of WBC and cancer cells in vivo; considerably more rigid than RBC, these cells may cause increased viscous resistance and transient vascular stasis in tumors. The implications of these results in tumor blood flow modulation using chemical and physical agents are discussed.

Adenocarcinoma↗

PubMed1986

Evaluation of a new dynamic viscometer for measuring the viscosity of whole blood and plasma.

We evaluated a new type of dynamic viscometer, the Sonoclot Coagulation Analyzer, for use in measuring the viscosity of whole-blood and plasma. Such information can be useful in monitoring patients with hyperviscosity syndromes, e.g., from multiple myeloma. A vibrating Teflon or plastic probe continuously measures dynamic viscosity. The instrument can be calibrated to measure a range of viscosities from 0.69 to 23 cP (mN X s X m-2) or more. The coefficient of variation at 0.69 cP was 3-4% for measurements with the Teflon probe, 7-9% with the plastic probe. Viscosity measured at 37 degrees C for plasma and whole-blood samples from 20 normal patients was 1.22 (SD 0.05) cP and 3.63 (SD 0.52) cP, respectively. Dynamic viscosity measured in blood samples from a single source, with contrived hematocrits ranging from 0 to 89%, increased exponentially as a function of hematocrit, confirming previous studies. Overall, we found this instrument simple and quick to operate, producing accurate, precise viscosity measurements over at least a 40-fold range of viscosity.

Blood Viscosity↗

PubMed1985

[Viscosity, pH and the protective properties of the diluents of bull seminal fluid after cryoconservation].

The changes in the values of viscosity and pH of some diluents in centrifugation and heat treatment and their protective qualities on bull semen at cryoconservation were followed up. It was found that following centrifugation of the gamma X22 pi diluent at 2,000 G for 20 min viscosity considerably dropped (from 2.240 +/- 0.1170 to 1.234 +/- 0.1153 centipoises). With the Nagaze Niva diluent treated under the same conditions the drop of viscosity was not reliable (from 1.368 +/- 0.1063 to 1.258 +/- 0.147). Following thermal treatment at 70 degrees C for 60 min viscosity in the first case considerably rose (from 2.440 +/- 0.1170 to 2.839 +/- 0.1319 centipoises), while in the second case the difference was not reliable (from 1.368 +/- 0.1063 to 1.706 +/- 0.2579 centipoises). After centrifugation at 2,000 G for 20 min and thermal treatment at 70 degrees C for 60 min the values of the two diluents' pH did not change. The drop of viscosity following centrifugation of the gamma X22 pi diluent was found to be associated a with a drop of its protective qualities on the spermatozoa too; and vice versa--the rise of viscosity of the same diluent following thermal treatment increased its protective qualities with regard to spermatozoa following cryoconservation. The centrifugation of the Nagaze Niva diluent at 2,000 G for 20 min and its thermal treatment at 70 degrees C for 60 min did not lead to statistically reliable changes in its viscosity. Neither were statistically reliable the changes in its protection of spermatozoa after cryoconservation.

Animals↗

PubMed1984

Blood viscosity studies in native and reconstituted polycythemic blood.

In twelve subjects with Polycythemia vera (P.V.) whole blood, plasma and relative viscosities and the main factors capable of influencing such parameters (Hct, RBCs, WBCs and platelet count, total proteins, gamma-globulins and fibrinogen) were investigated. Ten normal subjects of similar age and sex were studied as control. Whole blood viscosity was determined both in basal conditions and after reconstitution of Hct to normal values by adding some autologous plasma. After the reconstitution of Hct the subjects studied were divided into two groups on the basis of the correlation between Hct and whole blood viscosity. The first group (group A) had a good correlation between Hct and whole blood viscosity; on the other hand the second group (group B) did not show any significant correlation between these two parameters after reconstitution. In basal conditions none of the parameters capable of influencing whole blood viscosity or plasma viscosity permitted any discrimination between the two groups. The relative viscosity, which represents an indirect index of red blood cell deformability, appears to be more elevated in group B. Therefore, the different behaviour of polycythemic blood after reconstitution of Hct might be conceived to be due to a difference in red cell deformability.

Blood Cell Count↗

PubMed1984

[Methylation of erythrocyte membrane phospholipids: correlation with membrane viscosity. Study of normal and parkinsonian subjects].

Plasma membranes from erythrocytes were used to study various parameters: phospholipid methylation, viscosity and fragility. These parameters were analysed in 57 normal subjects (52 +/- 3 years old) and 14 patients with idiopathic Parkinson's disease without previous treatment (71 +/- 2 years old). No significant correlations were observed between the various parameters and sex or age in the normal group. No correlation was observed between fragility and methylation or viscosity. A statistically significant correlation was found between viscosity and phospholipid methylation. In the patients with Parkinson's disease, fragility is identical to the normal group but the viscosity is increased by 25 p. 100. The increase of viscosity is more obvious among the patients with a pure or predominantly akinetic form of the disease. These results favour the previously described correlation between phospholipid methylation and viscosity of the plasma membrane and suggest a modification of these parameters in Parkinson's disease. They also suggest that the increased viscosity observed in Parkinson patients could render the receptors inaccessible to their endogenous ligands.

Adolescent↗

PubMed1983

Echinocytes in the blood of hyperproteinaemic mice with proteinuria. Is the effect of such cells on blood viscosity the cause of the proteinuria?

Early studies in this series failed to obtain evidence for the cause of hyperproteinaemic proteinuria although it was speculated that blood viscosity, increased because of high plasma protein levels, might play a significant role. As we had no means of measuring blood viscosity it was decided to investigate the effects of reducing blood viscosity in a small number of mice made anaemic before subjecting them to albumin overload. All but one of the mice given injections i.p. of 250 mg HSA on 2 successive days developed proteinuria within 24 h of the first injection. This result seemed to show that altered blood viscosity was not a factor in the mechanism of the hyperproteinaemic proteinuria. However, it has been shown that changes in the red cell environment can lead to red cell deformation resulting in an increase in blood viscosity. To check on this possibility another small group of mice were injected with HSA as previously. On the morning after their second injection the mice were bled by percutaneous heart puncture and the blood was examined by scanning electron microscopy. This showed that a vast preponderance of red cells, probably more than 95%, were echinocytes. Although no measurements of blood viscosity were made, it can be speculated that hyperproteinaemic proteinuria is caused by the intraglomerular effects of blood with increased viscosity (because of the red cell transformation) being made more viscous by glomerular filtration. Enhanced protein filtration would occur because of the increase in glomerular pressure needed to restore flow of viscous blood at the efferent arteriole.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1982

Viscosity of culture medium as a regulator of synthesis and secretion of very low density lipoproteins by cultured hepatocytes.

It has been postulated that hyperlipidemia in the nephrotic syndrome is due to overproduction of lipoproteins and that low colloid osmotic pressure (due to hypoalbuminemia) triggers this. Secretion of very low density lipoproteins (VLDL) by cultured rat hepatocytes has been shown to be inhibited by albumin, globulins, and dextrans, but the effect did not correlate with osmolarity. In the present studies we tested the hypothesis that viscosity rather than osmolarity might be the parameter determining the effectiveness of macromolecules in inhibiting VLDL synthesis and secretion by cultured rat hepatocytes. Synthesis and secretion of VLDL was measured in terms of incorporation of [3H] glycerol into medium triglycerides and also from changes in the mass of secreted VLDL triglycerides and apoproteins. The viscosity of the culture medium was increased by addition of dextran-500, gelatin or methylcellulose MX 880. Synthesis and secretion of VLDL was inhibited in direct proportion to increasing viscosity. At a viscosity of 2, which is about that of normal plasma, VLDL secretion was reduced by 20%. An inhibition of 60-70% in secretion and 30-40% in synthesis of VLDL lipid and protein components was observed at a relative viscosity of approximately 3.7. This viscosity was obtained by addition of any of the following: 3% dextran, 3% gelatin, 0.2% methylcellulose, or a combination of 0.1% methylcellulose plus 2% gelatin. Thus, similar viscosities resulted in similar degrees of inhibition despite differences of up to 16-fold in mass concentration and up to 20-fold in osmolarity.

Animals↗

PubMed1982

[Significance & treatment of abnormal blood viscosities in pre-eclamptic patients (author's transl)].

Blood viscosity, a blood flow volume determinant, is one of the primary indicators of the state of pregnancy. The viscosity of peripheral veins was measured using a cone-plate viscometer (share rate 150 sec-1, 375 sec-1) and the results were utilized in comparisons between control and experimental groups to determine their importance to pre-eclamptic patients. Compared with values of 11 non-pregnant subjects (3.614 cp), 165 normal pregnancy cases had lower measurements during the entire term of pregnancy. The viscosity of these normal pregnant subjects decreased up to the 24th week, and increased thereafter. It is hypothesized that this results from the increased plasma volume of pregnant women. In severe pre-eclamptic subjects (3.508 cp), viscosity was significantly higher than in normal pregnancy cases. The natural decrease in peripheral blood flow resulting from elevated viscosity threatens the lives of both mother and fetus. Further analysis of clinical symptoms placed these 31 preeclamptic subjects in the conventional categories of hypertensive, proteinuric, and edematic. Viscosity measurements were highest for hypertensive (4.0059 cp), and lowest for edematic (2.7615 cp) and of intermediate value for proteinuric (3.2122 cp). To normalize these viscosities, the administration of dextran infusion therapy to hypertensive subjects and short-term furosemide therapy to edematic subjects was undertaken and brought considerable beneficial results.

Adenosine Triphosphate↗

PubMed1994

[Influence of viscosity on drug release from ointments, creams, gels and emulsions].

The authors studied the drug release from high number of water-free ointments, creams, emulsions and hydrogels. They targeted to find correlation between the viscosity of these pharmaceutical forms and their drug release. Neutral oil was the lipophilic phase of emulsions, the emulsifiers were from Tween and Tagat series. The creams tested consisted of ESMA ointment, Teginacid and/or Softisan emulsifiers and water in 60-80 w/w%. The drug release from Eudispert, methyl-cellulose and hydroxy-ethylcellulose gels was studied. The applied active ingredients were as follows: griseofulvin, sulfadimidine, salicylic acid and ephedrine hydrochloride. Relevant literature suggest a reciprocal correlation between the viscosity of ointments and the quantity of the released drugs. The authors confirmed the general validity of this correlation in case of the following preconditions: if the solubility and distribution of drug do not change along with the change of viscosity there is reciprocal ratio between viscosity and the quantity of drug released. This reciprocal correlation prevails only in a small range of viscosity, that is in systems resembling Newton's liquids. In cases of ointments and gels of higher viscosity a reciprocal relationship exists between the logarithm of viscosity and the quantity of drugs released.

Dosage Forms↗

PubMedDate not supplied

[Dynamic blood viscosity in selected respiratory system diseases].

The dynamic viscosity of blood was examined in 90 persons with different pulmonary diseases ill and in 56 with a normal state of health. Age was found not to have any effect on blood viscosity both in the male and female members of the control group, whereas in women aged below 40 blood viscosity was lower from that in men both before and after 40. Blood viscosity in women after 40 did not differ from blood viscosity in men, which may be explained by the effect of hormonal factors on blood viscosity in women. In the group of ill subjects, blood viscosity values were found to be increased to various degree; the highest values of that parameter were found in persons with lungs cancer. These values depended on blood protein disturbances found in that group, especially on the high concentration in blood of fibrinogen and gamma, alfa 2 and alfa 1 globulins.

Adult↗

PubMedDate not supplied

[Relationship between lipid profile and blood viscosity in a sample of Calabrian population].

Plasma viscosity is increased in subjects with risk factors for ischemic heart disease whereas the role of blood viscosity is controversial. Aim of the present study is to evaluate the relationship between blood lipids and blood viscosity. One hundred seventy eight male subjects have been enrolled, aged 35-70 years, participating in an atherosclerosis prevention campaign held in Catanzaro between September 1994 and April 1995. Subjects with previous myocardial infarction and/or plasma triglycerides > 400 mg/dl have been excluded. Blood pressure and body mass index (BMI) have been measured and blood has been withdrawn for determination of total cholesterol (T-CHOL), triglycerides, HDL-cholesterol (HDL-C), glucose and blood viscosity. Blood viscosity resulted significantly directly correlated to non HDL-C and inversely to HDL-C. The population has been divided in two groups according to T-CHOL/HDL-C ratio value. Subjects with T-CHOL/HDL-C > 5 showed increased values of blood viscosity, after adjustment for haematocrit, BMI and glucose. These results demonstrate that blood viscosity is strongly influenced by lipid profile. This might contribute to better understand the deleterious effects that elevated concentrations of blood lipids exert on arterial wall.

Adult↗

PubMed1998

[Modulation by nitric oxide of vasopressin induced renal vasoconstriction varies with perfusate viscosity in the isolated rat kidney].

Previously we reported that AVP is a potent vasoconstrictor in the TYRODE's perfused rat kidney. In vivo however AVP elicited only minor effects on renal blood flow. We hypothetized that differences in shear stress, particularly related to differences in viscosity could be involved. In this study, we investigate the role of perfusate viscosity in the modulation of AVP-induced renal vasoconstriction by NO. Experiments were performed in kidneys isolated from male Sprague-Dawley rats (220 g). Kidneys were perfused at a constant flow of 8 mL/min, in a recirculating system, with TYRODE's solutions supplemented with 6% bovin serum albumin (BSA) or 4.7% Ficoll 400 (Ficoll). The viscosities relative to water were respectively of 1.33 (BSA), 2.32 (Ficoll) and 1.03 (TYRODE). Concentration-response curves to AVP were constructed in the absence or presence of 100 microM N omega-nitro-L-arginine (L-NA), an inhibitor of NO synthase, and compared to those obtained in kidneys perfused with TYRODE's solution. AVP elicited a concentration-dependent renal vasoconstriction, with a progressive shift of the curves to the right and a small decrease in the maximum response when the kidneys were perfused with perfusates of increasing viscosities: logEC50 = -9.9 +/- 0.1 (TYRODE, n = 14), -9.7 +/- 0.1 (BSA, n = 5), -9.0 +/- 0.1 (Ficoll, n = 5) (m +/- e.s.m. Anova, p < 0.001); Emax = 34 +/- 1, 31 +/- 2 and 26 +/- 3 mmHg/mL/min (Anova, p < 0.001). L-NA abolished the differences between kidneys perfused with solutions of different viscosities in logEC50 for vasopressin (10.3 +/- 0.1, 10.4 +/- 0.1 and 10.5 +/- 0.1, n = 5-11, Anova, NS) but did not affect Emax values. In conclusion, present results show that 1) AVP-induced renal vasoconstriction is modulated according to the viscosity of perfusate and 2) NO is involved in this effect. Viscosity, a major determinant of shear stress, should be considered in hemodynamic studies performed on isolated kidneys.

Animals↗

PubMed2003

Study on the phase behaviors, viscosities, and thermodynamic properties of CO2/[C(4)mim][PF(6)]/methanol system at elevated pressures.

An apparatus to determine the vapor-liquid equilibria of CO(2)/ionic liquid (IL)/organic solvent multisystems and the viscosity of the liquid phase at elevated pressures has been constructed. The solubility of CO(2) in 3-butyl-1-methyl-imidazolium hexafluorophosphate ([C(4)mim][PF(6)]) and the viscosity of CO(2)-saturated [C(4)mim][PF(6)] have been studied at 313.15, 323.15, and 333.15 K and at pressures up to 12.5 MPa. The phase behavior of CO(2)/[C(4)mim][PF(6)]/methanol ternary mixture and the viscosity of the liquid phases at equilibrium condition have also been determined at 313.15 K and at 7.15 and 10.00 MPa. The partition coefficients of the components in the ternary system are calculated. Peng-Robinson equation of state and some thermodynamic functions are combined to calculate the fugacity coefficients of the components in the system. It demonstrates that the viscosity of the IL-rich phase decreases significantly with increasing pressure of CO(2), and the effect of temperature on the viscosity of CO(2)/IL mixture is not noticeable at high pressure, although the viscosity of the CO(2)-free IL decreases dramatically with increasing temperature. Compressed CO(2) may become an attractive reagent for reducing the viscosity of ILs in many applications. The mole fraction of methanol in the CO(2)-rich phase is much lower than that in the IL-rich phase; this indicates that the interaction between the IL and methanol is stronger than that between CO(2) and methanol. The fugacity coefficient of CO(2) in IL-rich phase is larger than unity, while that of methanol is much small than unity, which further suggests that methanol-IL interaction is much stronger than CO(2)-IL interaction. However, the CO(2)-IL interaction is stronger than the CO(2)-methanol interaction.

Journal Article↗

PubMed1999

Trophallaxis in the honeybee, Apis mellifera : the interaction between viscosity and sucrose concentration of the transferred solution.

Trophallaxis by honeybee foragers was studied under the experimental conditions of an arena. The behaviour of pairs of bees, one (donor) fed with 50-&mgr;l sucrose solutions and another unfed recipient, was analysed as a function of the sucrose concentration, the concentration at constant viscosity (kept constant by adding tylose, an inert polysaccharide), and of the viscosity of a 30% sucrose solution. By increasing the concentration of solutions, the rate at which the solution was transferred to recipient bees (transfer rate of solution, in &mgr;l/s) increased up to a maximum value for 30% sucrose solution, and decreased beyond this concentration (concentration experiment). At constant viscosity, no modulation was observed for the lower sugar concentration range (10-30%), while the transfer rate of solution clearly increased beyond 30% (concentration experiment at constant viscosity). For the 30% sucrose solution, the transfer rate decreased with increasing viscosity (viscosity experiment). If only the sucrose compound is comparatively analysed, the transfer rate of sucrose (in mg/s) increased similarly in the first two experiments. These results give behavioural evidence suggesting that donor bees are capable of modulating the trophallactic food transfer as related to the sucrose concentrations carried into their crops within a considerable wide range, but viscosity prevents it. It also suggests that trophallactic transfer rate does not depend on abdominal volume, for even when all donor bees attained similar loads (50 &mgr;l), transfer rate of solution increased along with the offered sucrose concentration. Results are discussed in relation to the information exchange performed in the foraging context displayed by foragers. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed2000

Shear Viscosity Behavior of Emulsions of Two Immiscible Liquids.

The viscous behavior of oil-in-water (O/W) emulsions is studied over a broad range of dispersed-phase concentrations (φ) using a controlled-stress rheometer. At low-to-moderate values of φ (φ<0.60), emulsions exhibit Newtonian behavior. The droplet size does not exert any influence on the viscosity of Newtonian emulsions. However, at higher values of φ, emulsions exhibit shear-thinning behavior. The viscosity of shear-thinning emulsions is strongly influenced by the droplet size; a significant increase in the viscosity occurs when the droplet size is reduced. With the decrease in droplet size, the degree of shear thinning in concentrated emulsions is also enhanced. The viscosity data of Newtonian emulsions are described reasonably well by the cell model of Yaron and Gal-Or (Rheol. Acta 11, 241 (1972)), which takes into account the effects of the dispersed-phase concentration as well as the viscosity ratio of the dispersed phase to continuous phase. The relative viscosities of non-Newtonian emulsions having different droplet sizes but the same dispersed-phase concentration are scaled with the particle Reynolds number. The high shear viscosities of non-Newtonian emulsions can be predicted fairly well by the cell model of Yaron and Gal-Or (Rheol. Acta 11, 241 (1972)). Copyright 2000 Academic Press.

Journal Article↗

PubMed1997

The effect of viscosity of semen diluents on motility of bull spermatozoa.

The effect of egg yolk extender on semen viscosity and bull sperm motility of fresh and cooled or deep frozen semen was determined by a computer-assisted system. Viscosity of the extender was determined by flow time. Based on the sperm velocity (velocity of the average path), individual spermatozoon were classified into groups of progressively motile (>==30 microm/sec) and immotile (<10 microm/sec) spermatozoa. The average velocity of progressively motile spermatozoa (VPM), the velocity of linear progressively motile spermatozoa (VLP) and the percentage of linear swimming spermatozoa (LIN) were evaluated. The addition of 10, 20 or 30% egg yolk to Tris buffer (pH 6.5) resulted in a linear decrease of VPM and a decrease in the percentage of progressively motile spermatozoa, but it increased the relative rate of LIN in fresh diluted semen. Increasing the levels of egg yolk in the diluent resulted in higher viscosity. The VLP was significantly higher than the VPM. In refrigerated or frozen semen samples, extender with 30 and 20% egg yolk had a similar effect on the VPM but not on the percentage of progressively motile sperm cells. Freezing of egg yolk (30%) extender to -20 degrees C resulted in a significant increased flow time and higher viscosity. Dilution of semen samples with high viscosity extender decreased the VPM in fresh and chilled semen. Freezing semen of high viscosity extender with glycerol had no apparent effect on the percentage of progressively motile spermatozoa compared with that of non-glycerinated egg yolk extender. The results suggest that different concentrations of egg yolk in the extender can influence the parameters of semen viscosity and sperm motility evaluated by a computer-assisted system.

Journal Article↗

PubMed1998

The Melt Viscosity of Dendritic Poly(benzyl ether) Macromolecules.

The zero shear melt viscosity, eta0, for a variety of dendritic poly(benzyl ether) macromolecules has been measured. The viscosity of low generation dendrimers exhibits a strong molecular mass, M, dependence, yet, direct proportionality between eta0 and M is observed at higher generations. The viscosity scales with M for mono- and tridendrons rather than generation number. Hypercore dendrimers continue this scaling although the viscosity is slightly greater. A large deviation from the master curve for the mono- and tridendrons is found for an end-substituted monodendron. The viscosity for the end-substituted monodendron is also much more temperature dependent than virgin dendrimers, and it is concluded that end groups have a much larger effect on the viscosity than the core. Reexamination of literature data for intrinsic viscosity and glass transition temperature is performed, and these quantities also scale with molecular mass. Comparison with free volume theory indicates that the theory is extremely robust although some question of its validity is made when applied to dendrimers.

Journal Article↗

PubMed1994

THE INFLUENCE OF HEMATOCRIT, TEMPERATURE AND SHEAR RATE ON THE VISCOSITY OF BLOOD FROM A HIGH-ENERGY-DEMAND TELEOST, THE YELLOWFIN TUNA THUNNUS ALBACARES

The high cardiac output, arterial blood pressure and cardiac energy demand of tuna make it likely that blood viscosity has an important influence on cardiovascular function. Furthermore, tuna regularly subject themselves to ambient temperature changes of 10°C or more during their daily vertical migrations. They can also maintain muscle temperatures several degrees Celsius above ambient and reach maximum muscle temperatures of approximately 15°C above ambient. The blood of tuna is, therefore, subjected to more frequent and rapid temperature changes than those that occur in other teleosts. Nothing is known, however, about the effects of temperature, shear rate or hematocrit on the viscosity of tuna blood. Viscosity of yellowfin tuna blood (hematocrits of 055 %) was measured at 15, 25 and 35°C and at shear rates of 45, 90, 225 and 450 s-1 using a cone-plate viscometer. As found for the blood of other vertebrates, viscosity increased with increasing hematocrit. Viscosity also increased nonlinearly with decreasing shear rate, until a shear rate of 90 s-1 was reached. There was no significant increase in viscosity when shear rate was decreased further, to 45 s-1. Because of the relatively flat hematocritviscosity curves, predicted optimal hematocrit curves were nearly flat above a hematocrit of approximately 30 %.

Journal Article↗