Robert J. Dellenback

Blood Viscosity: Influence of Erythrocyte Aggregation

The addition of purified canine or bovine fibrinogen to suspensions of canine erythocytes in Ringer solution caused an increase in viscosity and the formation of aggregates of erythocytes. Both of these effects became increasingly pronounced as the fibrinogen concentration was raised, and they approached plateaus with 1 gram of fibrinogen per 100 milliliters. An increase in shear rate (or shear stress) reduced both the effect on viscosity and the aggregate size. The data suggest that fibrinogen causes an increase in blood viscosity and a departure from Newtonian behavior by interacting with erythrocytes to form cell aggregates which can be dispersed by shear stress.

Blood viscosity: influence of erythrocyte deformation.

Suspensions of canine and human erythocytes hardened with acetaldehyde differ from the suspensions of normal erythrocytes with respect to their rheological behavior. Normal erythrocytes can be packed by centrifugation so that the sediment volume is nearly 100 percent cells, but the hardened erythrocytes (RBCs) can be packed only to approximately 60 percent cells. At the same cell percentage the viscosity of the hardened RBC suspension is higher than that of the suspension of normal erythocytes. An increase in shear stress deforms the normal erythocytes and lowers the suspension viscosity, but has no influence on the viscosity of the hardened cell suspension. In blood with high cell percentages, the shear deformation of normal RBCs plays an important role in reducing viscosity and facilitating flow at high shear stresses.

Plasma Trapping in Hematocrit Determination. Differences Among Animal Species.

Summary With the use of albumin-I131, the volume of plasma trapped in the packed cell column of hematocrit tubes was determined for blood samples obtained from 5 animal species. The volume of plasma trapped was least in blood samples obtained from elephant, man and dog (MCV 112 to 72 μ3), larger in sheep blood (MCV 37 μ3) and largest in goat blood (MCV 18 μ3). Increasing the force of centrifugation or removal of plasma proteins reduced the volume of fluid trapped in the packed cell column, and the reduction was most pronounced for goat blood.

The Extinction Coefficient of Fibrinogen from Man, Dog, Elephant, Sheep, and Goat at 280 mμ

Summary Fibrinogen from the plasma of man, dog, elephant, sheep, and goat was isolated, purified, and dialyzed free of (NH4)2SO4 against 0.005 M sodium citrate. The optical density at 280 mμ and the total nitrogen (micro-Kjeldahl) were determined on serial dilutions from each specie and the extinction coefficient E (0.1%) calculated. In the case of the dog, least square analysis of 38 determinations reveals that the equation y = 1.583x — 0.044 is the line of best fit, with correlation coefficient of 0.998. The extinction coefficient for a 0.1% solution of dog fibrinogen in 0.005 M sodium citrate is thus 1.583. Extinction coefficients, calculated as the ratio of optical density to fibrinogen concentration without least square analysis, for fibrinogen from other species have also been determined. These extinction coefficients show mean values of 1.55 for man, 1.58 for dog, 1.57 for elephant, 1.55 for sheep and 1.56 for goat, with the average value for all five species being 1.56. The use of this average value for these species as well as the cow introduces an error of only ±1%.

Centrifugal Packing of Suspensions of Erythrocytes Hardened with Acetaldehyde

Summary and Conclusions The centrifugally packed column of human or canine RBC hardened with acetaldehyde consists of only 60% cells, in contrast to the near 100% packing for normal RBC. This incomplete packing of hardened RBC was demonstrated with the isotope dilution method using three different macromolecules (albumin, dextran, and PVP) and by following the hematocrit values during the hardening process, and the results agree with theoretical calculations. The striking difference in the centrifugal packing of hardened vs normal RBC indicates that normal RBC are deformable during centrifugal packing and that the low degree of packing must be considered in any study on hardened RBC.

Hematocrit Changes in Endotoxin Shock.

Summary Intravenous injection of Escherichia coli endotoxin (3 mg/kg) caused marked rises of arterial cell percentage in dogs with spleen bin. not in splenectomized clogs. The increase in arterial cell percentage can be divided into 2 phases. The initial phase (0 to 10 minutes after endotoxin) was seen in all dogs with spleen and is attributable to the contraction of the spleen, since the cell percentage in the portal venous blood was markedly elevated, in this initial phase, the extravasation of protein-rich fluid from the splanchnic circulation was accompanied by an influx of protein-poor fluid from the kidneys and possibly other areas, hence the circulating plasma protein concentration decreased. The second phase of increase of arterial cell percentage (20 to 60 minutes after endotoxin) was associated with a rise in arterial plasma, protein concentration and is ascribed to an extravasation of protein-poor fluid. This second phase was more marked in dogs which died within 200 minutes after endotoxin. There were no significant alterations in the cell size of the arterial blood, whereas the cells in the venous blood swelled after endotoxin when pCO2 and acidity increased.

Influence of Fibrinogen and Globulins on Blood Rheology at Low Shear Rates: Comparison among Elephant, Dog and Man

In earlier studies on low-shear rheology of human blood (1,2,3), we have attributed the shear thinning behavior of blood to two major factors, namely erythrocyte deformation during cell-cell interactions and erythrocyte aggregation resulting from cell-protein interactions.

Change of Erythrocyte Deformability During Fixation in Acetaldehyde

In previous studies in our laboratory (1,2,3), the rheological behavior of erythrocytes hardened in acetaldehyde was compared with that of normal erythrocytes. The loss of deformability in the hardened erythrocytes was demonstrated by a reduction in the degree of centrifugal packing (1), an increase in suspension viscosity with a loss of shear thinning (2), and a decrease of transmission through sieves with small pores (3). The rheological demonstration of flexibility of normal erythrocytes is in agreement with microscopic observations under a variety of conditions (4,5,6,7). The present experiments were performed to study the time course of the loss of deformability as revealed by these rheological tests on human erythrocytes during their fixation in acetaldehyde. The results of these studies may provide a basis for the analysis of rheological behavior of erythrocytes with a partial reduction of deformability in hematological diseases.

Effect of Endotoxin on the Transfer of Fibrinogen from Plasma to Lymph.

Summary The fibrinogen concentration ratio between the thoracic duct lymph and the arterial plasma averages 0,41 in 10 dogs under pentobarbital anesthesia. Intravenous injection of endotoxin caused an increase of this L/P ratio to 0.7-0.8 which was sustained for at least 3 hours after endotoxin. The increase in the LP ratio for fibrinogen is associated with a rise in lymph flow, indicating a marked increase in capillary permeability to this protein. The increase in L/P ratio after endotoxin is due primarily to an increase in. lymph concentration, although there is a later decrease in plasma concentration. The decrease in plasma fibrinogen concentration is only partially due to fluid shifts and there is indication that specific decrease of fibrinogen concentration commences 30 minutes after endotoxin.

AGE CHANGES IN THE PLASMA GLYCOPROTEINS OF THE MONGOLIAN GERBIL.

Summary Age-related changes in the plasma glycoproteins of the Mongolian gerbil (Meriones unguiculatus) were studied in animals ranging in age from 1–3 days to 28 months. Analyses were performed using paper electrophoresis and periodic acid-Schiff staining, and glycoprotein percent composition values were calculated for albumin, alpha1-, alpha2-, beta- and gamma-globulin fractions. Alpha1-/beta-globulin glycoprotein ratios decreased with increasing age. Least affected by animal aging were the alpha2- and beta-globulin fractions, whereas the greatest percent changes were shown by alpha1-globulin, which steadily decreased with increasing age. All five plasma fractions contained significant quantities of glycoprotein material.