Dependence of Erythrocyte Deformability on Some Blood Constituents

Blood supply to tissues through small vessels may be disturbed by arteriosclerotic narrowing. Recent hemorrheology have shown that erythrocytes could pass through the capillaries with smaller diameters than those of erythrocytes deforming themselves. Then, the clinical evaluation of erythrocyte deformability may be advantageous in the study on the circulation in arteriosclerotic disorders. The aim of this study is to elucidate the influences of the blood constituents on erythrocyte deformability and the difference in erythrocyte deformability between arterial and venous blood. Venous blood specimens were drawn from cubital veins in 61 subjects aged from 22 to 84 years, and arterial blood specimens were collected in 14 subjects from femoral arteries. Erythrocyte deformability was evaluated by the deformability index measure using filtration method developed by Reid et al. Freshly drawn whole blood anticoagulated with 3.8% sodium citrate was filtered through polycarbonate membrane with 5μ diameter pores at a pressure gradient of 20cm of water. Deformability index was expressed as the blood volume passed through the membrane in 1 minute. Readings were taken in triplicate on each sample. Mean values and standard deviations were as follows: 1.07±0.17ml/min in the twenties, 0.95±0.09ml/min in the thirties, 0.95±0.13ml/min in the forties, 0.95±0.25ml/min in the fifties, 0.82±0.12ml/min in the sixties, 0.16±0.17ml/min over seventy years old. The index in subjects aged over seventy was significantly lower than those in the other age groups. The index was directly proportional to blood ATP content, and inversely to fibrinogen, hematocrit and hemoglobin. The concentration of ATP in the blood passed through the membrane was higher than that of ATP measured before filtration. Neither deformability index nor ATP level indicated significant arteriovenous gap. Therefore, venous blood should be preferable to arterial blood in the determination of erythrocyte deformability. Decreased deformability index in the aged subjects may relate the accelerated formation of ischemic lesions in the tissues perfused by sclerotic arteries. The direct correlation between the index and ATP content, and high concentration of ATP in the blood passed through the membrane are in accordance with previous findings.The close relations of the index to hemoglobin, hematocrit and fibrinogen indicate indirectly the contribution of erythrocyte deformability to blood viscosity as shown in previous papers. High blood viscosity promotes thrombus formation and may result in infarction. Therefore, in conclusion, the deformability index should be admitted as one of the useful measures in the observation of the aged subjects which might be accompanied with arteriosclerotic disorders.