To pass through the microcirculation, erythrocytes need to undergo considerable deformation. We performed an experiment to investigate the erythrocyte deformability in healthy adults and in patients with uncontrolled hypertension and controlled hypertension.

5ml of whole blood is anticoagulated with 2mg ethylenediaminotetra-acetic acid(EDTA). 1ml graduated plastic syringe, without its plunger, is filled with anticoagulated whole blood to the 1ml mark, And the syringe is put into the assembled membrane holder. Under standard condition, whole blood is passed through a 5µ polycarbonate membrane filter under negative pressure of 20cm H₂O. The studies are performed at roon temperature and within two hours of venipuncture.

Erythrocyte deformability was observed in 91 normal healthy adults and 25 patients with uncontrolled hypertension and 18 patients with controlled hypertension. Following results were obtained.

1) In male control age group I, II, III, the erythrocyte deformability indices were 0.776±0.125, 0.792±0.189, and 0.714±0.172 respectively and in female the indices were 0.880±0.138, 0.865±0.182 and 0.796±0.170 accordingly.

2) THe RBC deformability indices in female control troup were significantly higher than the male group in statistics(p<0.05).

3) No significant differences were observed among each age group in control.

4) In patients with uncontrolled hypertension, each age group I, II and III, the erythrocyte deformability indices were 0.785±0.050, 0.775±0.122, and 0.692±0.133 respectively and in control group, the indices were 0.8365±0.140, 0.8252±0.186 and 0.7534±0.173 accordingly. And in patients with controlled hypertension, the indices were 0.820±0.00, 0.788±0.135 and 0.716±0.141 accordingly.

5) The erythrocyte deformability inddex in patients with uncontrolled hypertension were significantly lower than the control group(p<0.05), and no significant differences were observed among each age group between male and female in patients with uncontrolled hypertension.

6) There was no significant statistical difference of deformability indices between uncontrolled group and controlled group(p>0.05).

This study reveals that the erythrocyte deformability in patients with essential hypertension is significantly lower than the healthy adults.