The elongation curve of RBC as determined by rheoscopy or ektacytometry (laser diffraction) resembles a rectangular hyperbola. The experimental data obtained so far included too large errors of measurement to allow precise mathematical description. The combination of laser diffraction with image analysis has im proved ektacytometry considerably, such that the error of measurement is reduced to less than 0.5%. In laminar flow RBC ofhealthy donors are elongated elliptically (j 0.001).Using the precise data of elliptical deformation, the elongation curve can be described to be hyperbolic. Hence, the double reciprocal plot gives a linear curve which over a wide range of shear stress (15 to 500 dyn/cm2) fits well the experimental data (r 0.99: p 0.001). The stress strain characteristics (i.e. elongation curve) can be described by two parameters: maximum elongation ( Epa ) iid the shear stress needed for half-maximum elongation ( KE).Mechanical stress only slightly reduces E but significantly shifts KE to higher values. Hyper-osmolarity decreases E and increases KE. Mild hypoosmolarity (>225 mOsm.) increases E and decreases KE, whereas strong hypo-osmolarity ( 225 mOsm.) decreases E and ftirther decreases KE Inclusion of elongation data measured at shear stress < 1 5 dyn/cm2 detonates the linear correlation. The elongation coefficients measured for low shear stress are higher than calculated by linear regression. The same holds true for range of shear stress between 1 5 and 25 dyri/cm2 if applied to RBC in hypertonic solutions or to cells which underwent mechanical stress.Further analysis ofthe laser diffraction patterns led us to suggest that at low shear stress the RBC become more or less oriented thereby presenting their side aspect (2.2 p.m .8 tm) to the laser beam. The diffraction pattern then resemble to those of elongated RBC. At shear stress exceeding 1 5 dyn/'cm2 the RBC rotate by 90° presenting their circular aspects (0 8 Rm) which then become elliptically deformed by shear. INTRODUCTIONThree closely related experimental set-ups have been established to quantitatively estimate deformability ofhuman RBC: rheoscopy, ektacytometry and laserdiffractoscopy. RBC are exposed within a viscometer to defined shear stress, which may be changed by varying the viscosity of the suspending fluid or the shear rate applied.Rheoscopy includes photomicrographic imaging in order to evaluate the geometric parameters of single cells. In ektacytometry the cell geometry is calculated via analysis of intensity at distinct points within the laser diffraction pattern. Laserdiffractoscopy uses the entire information content of laser diffraction patterns by means of image analysis and therefore is more precise than ektacytometry and less time consuming than rheoscopy.The flexibility of RBC determined by these methods is usually attributed to a single parameter E (or DI), derived from the quotient of the major and minor axis of elliptically deformed RBC (see figure 2). The stress strain characteristic (elongation curve) of whole RBC can b...

Selected hematological parameters and erythrocyte deformability indexes for 16 young male military students were compared before and after a period of exposure to heavy pollution. These students lived in Ankara, which has a serious air pollution problem. The mean sulfur dioxide levels measured at a station proximal to the campus where the students lived were 188 micrograms/m3 and 201 micrograms/m3 during first and second measurements, respectively. During the period between the two measurements, the mean sulfur dioxide level was 292 micrograms/m3. Significant erythropoiesis was indicated by increased erythrocyte counts and hemoglobin and hematocrit levels. Methemoglobin percentage was increased to 2.37 +/- 0.49% (mean +/- standard error) from 0.51 +/- 0.23%. Sulfhemoglobinemia was present in six subjects after the period of pollution, but it was not present in any student prior to this period. Significant increases in erythrocyte deformability indexes were observed after the period of pollution, i.e., from 1.13 +/- 0.01 to 1.21 +/0 0.02, implying that erythrocytes were less flexible, which might impair tissue perfusion.

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Most methods established so far to estimate RBC deformability are hard to standardize and include high error of measurement. For our present investigation on the effects of oxygen (02) and ozone (03) on red blood cell (RBC) deformability we used the method of laser diffiaction in combination of image analysis.Exposure to 02 (5.6-28 mg/mi) neither altered RBC deformability nor induced hemolysis. After adding 03 (2.-800 tg/ml) hemolysis (up to 2.3 g% free hemoglobin) was observed, but deformability did not change. Using very high concentrations ( 160 pg/ml 03) deformability decreased in a concentration dependent manner. When the antioxidant catalase mechanism of the RBC was inhibited with azide (1 mM), 02 did not affect RBC deformability, but was considerably reduced by 03 as well as by hydrogen peroxide (H202).After exposing RBC to 02 and/or 03 mechanical fragility was investigated by filtration of the RBC suspensions (hematocrit 5%) through 3 j.tm pore filter under pressure of 200 mmHg. Fragility remained unchanged after oxygenation. Astonishingly 03 in concentration 7pg/ml improved mechanical fragility (decrease ofhemolysis after mechanical stress).