IOHEXOL, PLATELET ACTIVATION AND THROMBOSIS I - IOHEXOL-INDUCED PLATELET SECRETION DOES NOT AFFECT THROMBUS FORMATION IN NATIVE BLOOD

Background: The nonionic monomer iohexol triggers in vitro platelet se cretion of beta-thromboglobulin (beta-TG). This iohexol platelet activ ation may promote intravascular thrombosis. We studied this relationsh ip by employing a human model of collagen-induced platelet thrombus fo rmation at arterial flow. The ionic dimer ioxaglate, the nonionic dime r iodixanol, and glucose were included. Methods and Results. In vitro platelet activation as measured by beta-TG secretion following a 1-min incubation of native blood with 50 vol% of iohexol was significant. G lucose solutions of 300, 580 and 825 mosmol, corresponding to the osmo lalities of respectively iodixanol, ioxaglate and iohexol, increased t he beta-TG secretion in parallel with the osmolalities. Ioxaglate and iodixanol were virtually inert. Continuous infusion of iohexol or 580 or 825 mosmol glucose (40 vol%) into flowing native blood at an arteri al wall shear rate of 2600 s(-1) in an ex vivo collagen-induced platel et thrombus formation device triggered pronounced secretion of beta-TG . However, the platelet thrombus formation in blood mixed with iohexol was within the same range as that observed with ioxaglate or iodixano l. Increasing glucose osmolality induced increasing beta-TG secretion, which paralleled gradually decreasing platelet thrombus formation. Co nclusion: Iohexol and 580 or 825 mosmol glucose trigger platelet secre tion of beta-TG. This secretion is not associated with enhanced collag en-induced platelet thrombus formation at high arterial shear.