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PubMed1982

Blood viscosity in experimental acute renal failure.

We measured blood viscosity in rats 24 h after induction of acute renal failure by glycerol or HgCl2 injections. The blood viscosity values of rats with acute renal failure were significantly higher than those of controls at any shear rates. The mean values of plasma fibrinogen in animals with glycerol - (302.5 +/- 35.2 mg/100 ml) or HgCl2 - (342.1 +/- 15.9 mg/100 ml) induced acute renal failure were significantly elevated compared to control levels (169.6 +/- 16.7 mg/100 ml). We believe that the increased blood viscosity in acute renal failure was primarily due to high concentration of plasma fibrinogen. The elevated blood viscosity may affect capillary microvascular circulation of glomerular capillary beds.

Acute Kidney Injury↗
PubMed1976

Blood viscosity and oral anticoagulant therapy.

During administration of bishydroxycoumarin, hematocrit, viscosity of whole blood, and viscosity of plasma decreased in samples from nine healthy volunteers and 31 patients who had coronary heart disease. The relationships between viscosity of blood and intensity of anticoagulant therapy varied from patient to patient. Discontinuation of the drug was followed by return of viscosities to pretreatment levels in two to four days. The decrease of viscosity of blood by anticoagulant therapy may explain the relief of anginal pain in patients who have coronary heart disease.

Administration, Oral↗
PubMed1980

Blood viscosity in young male diabetics with and without retinopathy.

Blood viscosity (shear rates 100s-1 and 0.94s-1) and several of its major determinants (haematocrit, plasma fibrinogen and plasma viscosity) have been measured in 38 male insulin-treated diabetics, aged 18-50 years, and in 38 non-diabetic control subjects matched for age and smoking habit. Diabetics without fundoscopic retinopathy (n=20) had higher mean blood viscosity than controls at the high shear rate (7.07 cP vs 6.75 cP, p < 0.05) and the low shear rate (21.2 cP vs 18.7 cP, p < 0.025). These differences persisted after correction of blood viscosity to a standard haematocrit, and were associated with increased plasma viscosity (1.41 cP vs 1.34 cP, p < 0.025) and plasma fibrinogen (2.9 g/L vs. 2.5 g/L, p < 0.025). Diabetics with retinopathy (n = 18) had higher mean blood viscosity than diabetics without retinopathy at the high shear rate (7.53 cP vs 7.07 cP, p < 0.05) and the low shear rate (24.3 cP vs. 21.2 cP, p < 0.05), associated with a higher haematocrit (p < 0.05). Blood viscosity and haematocrit correlated with the duration of diabetes (r > 0.32, p < 0.05).

Adolescent↗
PubMed1977

[Study of blood viscosity for evaluation of peripheral circulation in ischemic heart disease].

An important role in the characterization of the functions of the circulatory system belongs to the interrelationship between blood viscosity and central haemodynamics. Blood viscosity was studied in comparison with the pulse rate, arterial pressure and Robinson's index in patients with chronic forms of ischaemic heart disease. The examinations were conducted at rest and at the peak of sub-maximal bicycle tests. In normal individuals blood viscosity increases along with the increasing workload of the exercise. In patients with ischaemic heart disease performing threshold exercises the shifts in blood viscosity were varidirectional. In patients without circulatory insufficiency blood viscosity was changing in the same way as in normal individuals. In patients with cardiac insufficiency it either remained unchanged, or decreased. An increasing blood viscosity in normals under physical exercises may be interpreted as a mechanism of homeostasis preservation. A lack of growing blood viscosity under threshold exercises in patients with ischaemic heart disease and circulatory insufficiency indicates to disorders in the mechanisms of homeostasis preservation. Increasing blood viscosity may be due to impaired tissue oxygenation.

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↗
PubMedDate not supplied

Whole blood viscosity in beta thalassemia minor.

Patients with heterozygous beta-thalassemia minor have a decreased hematocrit (HCT). Since the HCT is a primary determinant of whole blood viscosity, the known reduction in HCT in beta-thalassemia minor should lead to a measurable reduction of whole blood viscosity. The influence of the relatively lower mean corpuscular volume and consequent higher red blood cell count and beta-thalassemia minor on whole blood viscosity using a microporous viscometer has not previously been the subject of investigation. Accordingly, the blood of a group of normal and beta-thalassemia minor subjects was examined with a microporous viscometer to elucidate further the relations between whole blood viscosity, HCT, and red blood cell count. The data show that for normal and beta-thalassemia minor subjects a significant positive correlation (r = 0.65, p less than 0.01) exists between HCT and whole blood viscosity. However, the slope of the regression of whole blood viscosity and HCT of beta-thalassemia minor subjects was significantly higher z = 3.14, p less than 0.001) than that of normals. Thus, for any given HCT their whole blood viscosity was higher than that of normals. Studies of the relation of red blood cell counts to whole blood viscosity indicate the higher whole blood viscosity at a given HCT was related to the increased red blood cell counts in beta-thalassemia minor subjects. Because of the opposing interactions of HCT and red blood cell counts, the mean whole blood viscosity of the group of beta-thalassemia minor subjects examined was not significantly lower than the normal whole blood viscosity.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Viscosity↗
PubMed1988

[Effects of local vibration exposure on whole blood viscosity in rats].

To investigate the relationship between vibration hazards and blood viscosity, vibration exposure experiments were conducted. The rat's hind limbs were continuously exposed to local vibration (60 Hz, 5 G) for 4 h. The exposed group showed a slightly lower blood viscosity and plasma fibrinogen in the blood obtained immediately after exposure when compared with the control group. However, in the blood obtained 18 h after exposure, there was no significant difference in the levels of whole blood viscosity and plasma fibrinogen between the exposed group and the control group. Hematocrit was not affected by this exposure. These results indicate that the decrease in the levels of whole blood viscosity induced by local vibration exposure is transient and that some relationship exists between changes of whole blood viscosity and those of plasma fibrinogen.

Animals↗
PubMed2001

Decrease in coronary blood flow reserve during hyperlipidemia is secondary to an increase in blood viscosity.

BACKGROUND: During maximal hyperemia, capillaries provide the greatest resistance to flow. A major determinant of capillary resistance is viscosity. We, therefore, hypothesized that abnormal coronary blood flow (CBF) reserve observed during hyperlipidemia is secondary to increased blood viscosity and not abnormal coronary vasomotion. METHODS AND RESULTS: Maximal hyperemia was induced in 9 dogs using adenosine. Serum triglyceride levels were increased by incremental doses of Intralipid. A good correlation was noted between serum triglyceride levels and blood viscosity (r=0.82). Neither total coronary blood volume nor myocardial blood volume changed with increasing serum triglyceride levels, indicating lack of vasomotion. Myocardial vascular resistance (MVR) increased with increasing triglyceride levels (r=0.84), while hyperemic myocardial blood flow (MBF) decreased (r=-0.64). The decrease in hyperemic MBF was associated with a decrease in blood velocity (r=-0.56). These findings were confirmed with direct intravital microscopic observations in the mice cremaster muscle. CONCLUSIONS: Increasing lipid levels in a fully dilated normal coronary bed causes no change in large or small vessel dimensions. Instead, the increase in blood viscosity causes capillary resistance to rise, which attenuates hyperemic CBF. Therefore, the abnormal CBF reserve associated with hyperlipidemia is due to increase blood viscosity and not abnormal vascular function.

Adenosine↗
PubMed1981

Prognostic value of initial blood viscosity on vascular surgery and treatment in peripheral disease.

The correlation between extent of arteriosclerosis and blood viscosity, and the reduction in viscosity after successful surgery support the hypothesis that a raised viscosity is a consequence rather than a cause of arteriosclerosis. Measurement of blood viscosity was of little practical help to our team of vascular surgeons when they were faced with the problem of which reconstruction to do and when to do the procedure on a particular patient. The results of our studies show that in patients with arteriosclerosis, in whom only the major arteries are affected, the viscosity of the blood is not grossly abnormal and a knowledge of the blood viscosity does little to influence treatment. Patients with peripheral vascular disease affecting the small arteries and arterioles often have a high blood viscosity. In these circumstances manipulation of blood viscosity by hemodilution or drugs may be of benefit, and there is evidence that isoxsuprine given intravenously can achieve a reduction in viscosity.

Arteriosclerosis↗
PubMed1981

Cerebral blood flow and blood viscosity in patients with polycythaemia secondary to hypoxic lung disease.

Blood viscosity, cerebral blood flow (CBF) and cerebral oxygen carriage (CBF X arterial oxygen content) were measured in 12 patients with polycythaemia secondary to hypoxic lung disease. CBF and cerebral oxygen carriage were both significantly higher than in a comparative group of 20 patients with raised packed cell volumes and normal lung function. The patients with secondary polycythaemia then underwent venesection and their mean packed cell volume fell from 0.613 to 0.495. This led to a consistent reduction in blood viscosity, which fell by 44% at a low shear rate (0.67/s) and 33% at a high shear rate (0.91/s). CBF rose by 21% (p less than 0.01), but cerebral oxygen carriage did not significantly increase in the group as a whole. Four of the patients with secondary polycythaemia had complained of episodes of confusion before venesection, which improved considerably once the packed cell volume had been lowered. Headache was relieved in a further two patients and none of the subjects was adversely affected by venesection. It was not possible, however, to show a correlation between symptomatic improvement and an increase in cerebral oxygen carriage.

Aged↗
PubMed2006

Changes in blood viscosity with the recombinant tissue plasminogen activator alteplase.

We measured whole blood viscosity to investigate the time course of the fibrinolytic activity of the recombinant tissue plasminogen activator alteplase. Changes in blood viscosity over time were determined using an oscillation-type viscometer at a shear rate of 400 to 500 per second. Blood viscosity initially increased with alteplase as in untreated blood, but then decreased, reflecting the fibrinolytic activity of generated plasmin. Blood viscosity subsequently stabilized at a level below the initial value owing to the dissolution of both fibrin and fibrinogen by alteplase. To our knowledge, the present study is the first to examine the time course of changes in BV during fibrin formation and degradation. The results indicated that the fibrinolyic agent alteplase might provide the additional benefit of increasing blood flow by lowering blood viscosity.

Blood Viscosity↗
PubMed1977

[Blood viscosity measurements in coronary infarct patients].

In 63 patients with myocardial infarctions happening longer ago as well as in 17 patients with acute myocardial infarction the viscosity of blood was measured and compared with the values of a control group of 34 healthy persons which was compiled after exclusion of known factors effecting on viscosity, such as hyperfibrinogenaemia or increase of hematocrit. The viscosities of the patients with infarction were significantly higher in all degrees of severity than those of the healthy persons. The hematocrit value, the fibrinogen and cholesterol level which were significantly higher in patients with infarction than in healthy persons were regarded as an explanation for this. Apart from this there existed an increase of the factors of risk total lipids, triglycerides and uric acid in the serum in cases with infarction. The increased blood viscosity may be regarded as a factor of risk for the myocardial infarction, according to our investigations.

Blood Viscosity↗
PubMed1981

The effects of mannitol on blood viscosity.

To determine the effect of mannitol on blood viscosity, serial measurements were carried out on venous blood in patients undergoing craniotomies for intracranial aneurysms. Blood samples were drawn immediately prior to, and 30 minutes, 2, and 4 hours after administration of mannitol. Complete blood counts, serum osmolarities, and erythrocyte microsieving studies were also performed on each sample. Whole-blood viscosity decreased at 30 minutes and 2 hours, but not at 4 hours after mannitol administration. This decreased appeared at high shear rates only, where erythrocyte deformability is critical viscosity. This effect was independent of the hematocrit. Removal of mannitol from the suspension returned red cell deformability to preadministration values indicating that the increased erythrocyte deformability required the presence of mannitol and the relative hyperosmolarity induced by this agent. The reduced erythrocyte rigidity and subsequent decreased whole-blood viscosity should enhance tissue perfusion in the microcirculation.

Blood Viscosity↗
PubMed2003

[The effect of local vibration on blood-lipids and whole blood viscosity].

OBJECTIVE: To study the effects of local vibration on blood-lipids and whole blood viscosity. METHODS: The total cholesterol (TC), triglyceride (TG), high density lipoprotein (HDL), low density lipoprotein (LDL), whole blood viscosity, apolipoprotein (Apo-), red blood cell (RBC), platelet (PLT), mean corpuscular volume (MCV), serum-protein, postprandial blood sugar (PBS), and serum-protein of experimental and control workers were detected. The difference of the means and abnormal rates of two groups were compared. RESULTS: The means of TG, TC, HDL in exposed group [(1.01 +/- 0.85), (3.25 +/- 0.61), (1.14 +/- 0.20) mmol/L respectively] were significantly lower than that of control group [(1.89 +/- 1.47), (3.87 +/- 0.82), (1.22 +/- 0.26) mmol/L, respectively, P < 0.01 or P < 0.05]. Apo-A was also decreased [(1.13 +/- 0.29) g/L vs (1.23 +/- 0.16) g/L, P < 0.01]. The mean of whole blood viscosity were significantly increased in exposed group [(2.76 +/- 0.42) mPa.s vs (2.54 +/- 0.33) mPa.s, P < 0.01]. The abnormal rate of Apo-A was significantly higher in exposed group (23.30%) than that in control (4.50%, P < 0.01). CONCLUSION: Local vibration may induce decrease in blood lipids, increase in blood viscosity and changes in some other blood parameters.

Adult↗
PubMed2006

Effects of nattokinase, a pro-fibrinolytic enzyme, on red blood cell aggregation and whole blood viscosity.

The vegetable cheese-like food, natto, is extremely popular in Japan with a history extending back over 1000 years. A fibrinolytic enzyme, termed nattokinase, can be extracted from natto; the enzyme is a subtilisin-like serine protease composed of 275 amino acid residues and has a molecular weight of 27.7 kDa. In vitro and in vivo studies have consistently demonstrated the potent pro-fibrinolytic effect of the enzyme. However, no studies to date have evaluated the effects of nattokinase on various hemorheological parameters and thus we have begun to assess the effects of the enzyme on RBC aggregation and blood viscosity. Blood samples were incubated with nattokinase (final activities of 0, 15.6, 31.3, 62.5 and 125 units/ml) for 30 minutes at 37 degrees C. RBC aggregation was measured using a Myrenne MA-1 aggregometer and blood viscosity assessed over 1-1000 s(-1) with a computer controlled scanning capillary rheometer (Rheolog). Our in vitro results showed a significant, dose-dependent decrease of RBC aggregation and low-shear viscosity, with these beneficial effects evident at concentrations similar to those achieved in previous in vivo animal trials. Our preliminary data thus indicate positive in vitro hemorheological effects of nattokinase, and suggest its potential value as a therapeutic agent and the need for additional studies and clinical trials.

Blood Viscosity↗
PubMed1985

[Effects of reduction of blood viscosity at constant hematocrit on the cerebral blood flow].

It is well established that cerebral blood flow (CBF) is low in patients with high hematocrit and is high in anemic patients. An inverse relationship between CBF and hematocrit has been found. Furthermore, if hematocrit is reduced, CBF increases. There is some debate as to whether these observations are due to viscosity or to oxygen carrying capacity of the blood. In order to further elucidate this problem, CBF, blood viscosity and hematocrit were measured in 4 patients with paraproteinemias before and after paraproteins had been removed by plasmapheresis without changes in hematocrit. After plasmapheresis, blood viscosity significantly decreases and CBF increases by a mean of 24.4 ml/100 g/min. Mean arterial blood pressure and hematocrit were not influenced by plasmapheresis. These results indicate that blood viscosity is an important factor in determining CBF. This does not exclude the role of oxygen transport as an associated factor, but it is evident that oxygen transport and blood viscosity are independent variables in the control of CBF.

Blood Viscosity↗
PubMed1992

How blood viscosity influences changes in circulation during pregnancy?

The changes of whole blood viscosity and plasma viscosity were studied in 15 normal non-pregnant women, and 120 normal pregnant women ranging from 8 to 39 weeks of gestation. The values of whole blood viscosity during normal pregnancy were significantly lower from 20 to 31 weeks of gestation than those in the other periods of gestation, and there was a positive correlation between whole blood viscosity and hematocrit. Plasma viscosity, however, did not change significantly during pregnancy. There was no correlation between whole blood viscosity and plasma viscosity, and there was also no correlation between plasma viscosity and plasma fibrinogen concentration. These findings suggest that decreases in whole blood viscosity, resulting from the change of packed-cell volume, may strongly contribute hemorheologically to the decrease in peripheral resistance during the second trimester.

Blood Circulation↗
PubMedDate not supplied

Elevated blood viscosity in alloxan diabetic dogs and experimentally galactosemic dogs.

Blood viscosity was investigated in alloxan-diabetic dogs and in dogs made experimentally hyperglycemic by a galactose-rich diet. The diabetics were prospectively assigned to levels of glycemic control ranging from poor to good. After up to 5 years of study, the blood viscosity of hyperglycemic diabetic animals was significantly greater than normal at both high (100 sec-1) and low (0.1 sec-1) shear rates. Blood viscosity at the low shear rate correlated closely with fibrinogen concentration, (r = 0.75; p less than 0.02) but not with HbA1 concentration (r = 0.14) in the diabetics. Galactosemic animals likewise had elevated blood viscosity at the low shear rate, but the correlation of viscosity with fibrinogen concentration in those animals was not statistically significant (r = 0.42). Plasma viscosity tended to be elevated in both diabetes and galactosemia, but not to a statistically significant degree.

Animals↗