EFFECT OF A LOW-OSMOLALITY NONIONIC CONTRAST-MEDIUM (IOPROMIDE) ON BLOOD-PLATELET MEMBRANE-STRUCTURE AND AGGREGATION

Nonionic contrast media (NICM) used in radiology exhibit weaker antico agulant properties than ionic media. This study was intended to evalua te the effect of iopromide NICM upon the platelet aggregation and thei r membrane structure (investigated by electron paramagnetic resonance method with a spin label). Blood was collected directly from the left ventricle during coronary angiography prior to and following the appli cation of the contrast medium. These results were compared with in vit ro examinations. Based on the spectral curves parameters that reflect conformational changes in membrane proteins were determined. The iopro mide-induced decrease in platelet aggregation examined in vitro with a denosine diphosphate (ADP), collagen and ristocetine was statistically significant. In vitro platelet membrane structure was modified signif icantly with regard to both protein conformation and the accessibility of sulfhydryl (-SH) and amino (-NH2) groups. In ex vivo studies the c hanges in platelet aggregation was only observed with ADP, whereas in the membrane-structure modifications were only noted regarding accessi bility of -SH and -NH2 groups. We conclude that iopromide-induced plat elet aggregation changes are most probably due to their membrane-struc ture modifications, whereas the less-pronounced contrast effect ex viv o is due to its rapid dilution in the inflowing blood. The results con firm weak antiplatelet and anticoagulant influence of NICM in vivo.