Effect of water-soluble iodinated contrast media on red cell shape and blood viscosity

Abstract

The effect of water-soluble iodinated contrast media on erythrocyte membrane was investigated systematically by the measurement of shape change and viscosity of red cell suspension the osmolality, viscosity and iodine content of all agents were arranged in proper. There was little difference in blood viscosity under the isoosmolality condition (300mOsm/kgH₂O) between ioxaglate solution (1.46cp), diatrizoate solution (0.96cp) and NaCl solution (0.8cp), while a little shape change was induced by ioxaglate and by diatrizoate under this condition. It was, therefore, evident that the difference in blood viscosity was due mainly to the difference in viscosity of contrast solution. Metrizamide caused a striking shape change and an increase in blood viscosity under this condition. An increase in blood viscosity was induced by hypertonic diatrizoate solution under the condition of equal viscosity (1.29cp, 618mOsm/kgH₂O) and of equal iodine content (115mgI/ml, 623mOsm/kgH₂O). These hypertonic diatrizoate solutions also caused remarkable shape changes, which were almostly equivalent to those induced by hypertonic NaCl solution (628mOsm/kgH₂O). Ioxaglate solution, the osmolatity of which was almost isotonic under these conditions, had less rheological and morphological effects on erythrocytes than diatrizoate solution. It was, consequently, clear that the rheological effect of the contrast solution was attributable only to the viscosity of contrast solution but also to the osmolality of it. There was little difference in blood viscosity and in red cell shape between ioxaglate, diatrizoate and NaCl solution under the physiological condition (300mOsm/kgH₂O, 15.0mgI/ml, 0.8cp). Metrizamide, however, caused obvious shape change and increase in blood viscosity even under this condition. It appeared that the effect of metrizamide solution on erythrocyte membrane was not attributable to viscosity or osmolality but to loss of membrane stability induced by certain direct effect of metrizamide on cell membrane. This experiment showed also that the iodine conjugated in contrast compounds were less toxic than free iodine ion.
In conclusion, it, was revealed that the membrane stability of erythrocytes ought not to be changed by contrast media. Furthermore, the osmolality of a contrast solution was elucidated as animportant factor more than the viscosity or iodine content in reference to the physiological behavior of erythrocytes.