[In vitro effects of ionic and non-ionic contrast media on erythrocyte aggregation]

An in vitro model was designed to examine the effect of three contrast media (CM): two non ionic (Iohexol, Iopamidol) and one ionic (Ioxaglate) molecules on erythrocyte aggregation. Red blood cells were suspended in a chemically defined medium (Albumin: 10 g/l), Immunoglobulins: 12 g/l, Fibrinogen: 1.5 g/l) supplemented with various proportions of CM (10-25% V/V). Control samples contained NaCl or Saccharose solutions with a nearly similar osmolality. Erythrocyte aggregation at constant hematocrit (HT = 40%) was determined by the analysis of the light backscattered by blood suspension during the aggregation process. As compared to control samples, non ionic CM induced a weak decrease in erythrocyte aggregation, when the ionic molecule caused a marked increase in the aggregation, which was related to CM concentration. A different interaction of ionic and non ionic CM with erythrocyte membranes has been shown by fluorescence studies. After addition of CM, it was noted a fluorescence quenching of lipophilic probes (TMA-DPH and DPH) embedded in erythrocyte membranes. This quenching probably due to benzene ring and iodine atoms of contrast media markedly varied according to the used fluorescent probe and the CM. In the presence of ionic CM, the fluorescence quenching is more important than that induced by non ionic CM. Thus, besides osmolality and viscosity of CM which play a role in erythrocyte aggregation, some intrinsic properties of CM such as the ionic or non ionic nature could influence erythrocyte membrane-contrast medium interactions and consequently erythrocyte aggregation.