528 
HEMODYNAMICS 
lu 4 
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45% RBC IN RINGER -i-^ 
ELEPHANT 
GOAT 
Table II. — Jei Fragility Test Results 
0 05 10 1-5 
FIBRINOGEN CONCENTRATION (g%) 
Figure G. — Influence of fibrinogen concentration on 
shear dependence of viscosity of 45% cell suspension 
in Ringer solution + fibrinogen. The curve for man 
was obtained by adding purified fibrinogen from ele 
phant (A), man (•) and goat (□) to human RBC. 
In all other species autologous, purified fibrinogen 
was used (from Ref. 1). 
as a result of a suddenly applied force is a con- 
stant for all mammalian RBC. Forstrom' has 
designed and tested a device called the jet 
fragility test to explore the strength of RBC. 
Saline is rapidly jetted through a 23 gauge 
needle into an initially stagnant reservoir of 
blood (see Figure 8). 
Results of a typical experiment are shown 
in Figure 9. In this test, 2 cc of saline were 
jetted into 1 cc of human blood reduced in 
hematocrit with saline to 8%. We choose to 
characterize a blood sample by the critical ve- 
locity, Uc, the velocity corresponding to the 
intersection of the line at zero hemolysis. Here, 
Uc is 2100 cm/sec and the flow is turbulent 
(Reynolds number of about 7000). The mech- 
anism of jet lysis is thought to be related to 
either turbulent shear stresses or pressure 
fluctuations, both having a value about t = 
0.017 pUe-.i* 
Data for seventeen different mammals are 
summarized in Table II and plotted in Figure 
10 as critical velocity versus cell volume. The 
data are represented reasonably well by the re- 
lation Uc^ V = constant, which can be expressed 
as rV = constant. This rupture stress relation 
will now be related to the cell membrane tension. 
As we have seen above, static cell dimensions 
Mammal (#) 
(Volume (/li'') Uc(cm/sec) 
Human Cord (12) . 
Human Female (14) 
Human Male (26) 
Hamster (10) 
Dog (19) 
Raccoon ( 1 ) 
Rabbit (3) . 
Squirrel Monkey (2) 
Brown Bear (1) . . 
Guinea Pig (1) 
Rat (10) 
Pig (1) 
Mouse (10) 
Siberian Tiger (1) . 
Domestic Cat (1) _ 
Horse (1) 
Cow (2) . _ 
Sheep (4) 
Goat (1) 
103 
1930 
84 
2120 
84 
2240 
62 
2260 
72 
2310 
44 
2310 
70 
2330 
63 
2380 
52 
2390 
76 
2460 
64 
2470 
58 
2700 
48 
2800 
53 
3070 
39 
3150 
37 
3510 
32 
3850 
31 
3880 
24 
6800 
do not characterize a flowing red blood cell. In 
velocity gradients, RBC are distorted and de- 
form into shapes we may approximate by a 
cylinder with hemispherical ends but with the 
FIBRINOGEN CONCENTRATION ( 9%) 
Figure 7. — (a) Influence of fibrinogen concentration on 
RBC aggregation. In 0.57c cell suspensions the aver- 
age number of RBC in each aggregation unit was cal- 
culated, (b) Influence of fibrinogen concentration on 
shear dependence of viscosity of 45% cell suspensions 
(from Ref. 1). 
