Diminished osmotic and chemically induced haemolysis of human erythrocytes following exposure to contrast media molecules.

Radiocontrast molecules (RCM) used in coronaroangiography and/or urography diminished their osmotic fragility when they were incubated for 30 min with human erythrocytes. The shift of the osmotic fragility curve towards lower NaCl concentration is related to the hypertonicity of RCM, but in addition, at a given osmolality (100 +/- 5 mosm/kg), RCM at the concentration of 4-10% v/v increase the resistance to osmotic lysis or even suppress it. Similar protection is observed towards erythrocyte lysis induced by a detergent (saponin), polyenic antibiotic (filipin) or non-polyenic cholesterol-specific agent (digitonin). The effect is (1) proportional to the amount of RCM present, (2) independent of hypertonicity of the molecule, and (3) related to the nature of acidic molecules. A weak insertion of RCM into the erythrocyte membrane is suggested since it was suppressed by a single washing of the cells.