The reliability of thrombotic tendency measured by intravascular wires in the rat

The objective was to determine if the amount of thrombus on two adjacent wires in an artery or in a vein was similar, and whether an upstream wire affected thrombosis on the downstream wire. Two 2 cm platinum wires were placed at adjoining sites in the abdominal vena cava and a further 2 in the abdominal aorta in 26 male and 24 female rats. In the artery, mean thrombus weight on the aortic downstream wire, set where the vessel is narrow, was significantly (p < 0.001) less than on the upstream wire, but the two correlated fairly well correlation coefficient (r = 0.608). In the vein, mean thrombus weight deposited in 1 hour was comparable on the pairs of wires both in males (r = 0.819) and females (r = 0.805). The mean downstream thrombus was slightly (10%) heavier than the upstream one both in males and females, a possible effect of vessel diameter, or of an activation by the upstream wire of thrombosis on the downstream one. An experiment to clarify that issue showed mean downstream venous thrombus to be again heavier than mean up-stream in both sexes (22 males, 30 females), and heavier than in controls in which no upstream wire was inserted. The platinum wire venous model seems to measure individual thrombotic response in a reasonably reproducible way in the rat. Upstream venous wire appears to activate thrombosis downstream from it by some 10%.