Effects of two low-osmolar contrast media, ioxaglate and iopamidol, on erythrocyte membrane elasticity.

RATIONALE AND OBJECTIVES: The effect of ioxaglate and iopamidol, two recently developed low-osmolality contrast media, on the shear elasticity of erythrocyte membranes was studied at an iodine concentration of 300 mg/mL and at a 20% volume concentration and compared with that obtained for control solutions matched in osmolality. METHODS: The authors used a micromanipulation technique, which consists of visualizing deformations of individual erythrocytes when gently aspirated into the tip of a glass micropipette by an accurately controlled pressure. An erythrocyte membrane shear elasticity modulus mu was then deduced. An increase in mu corresponded to an increase in erythrocyte membrane rigidity. RESULTS: In all cases, the erythrocytes remained discocytic. The shear elasticity modulus of the erythrocyte membrane is found to be (1) in the presence of ioxaglate (4.3 +/- 0.9 microN/m) lower (P < .001) than in the presence of hyperosmolar saline (6.2 +/- 1.3 microN/m) and lower (P < .02) than in the presence of iso-osmolar control (4.7 +/- 0.7 microN/m); (2) in the presence of iopamidol (5.4 +/- 0.7 microN/m) lower (P < .001) than in the presence of hyperosmolar sucrose (6.4 +/- 1.2 microN/m) and higher (P < .001) than in the presence of iso-osmolar control (4.7 +/- 0.7 microN/m); and (3) lower (P < .001) in the presence of ioxaglate (4.3 +/- 0.9 microN/m) than in the presence of iopamidol (5.4 +/- 0.7 microN/m). CONCLUSIONS: Under the experimental conditions used, both contrast media (ioxaglate and iopamidol) modify the erythrocyte membrane shear elasticity modulus less than do the matched hyperosmolar controls. Moreover, ioxaglate makes the erythrocyte membrane less rigid, and iopamidol makes the erythrocyte membrane more rigid than does the iso-osmolar control.