Effects of estradiol on myointimal thickenings from catheter injury and on organizing white mural non-occlusive thrombi.

The objective of this present study was to determine the effect of estradiol on the organization of white, mural, nonocclusive thrombus produced with a permanent, indwelling catheter in the abdominal aortae of rabbits and on myointimal thickenings produced by catheter injury but with only transient adhesion of platelets and no thrombosis in the thoracic aorta. Estradiol did not significantly alter the weight of thrombus or myointimal thickenings produced nor did it qualitatively or quantitatively alter Evans Blue uptake by the 7-day myointimal thickenings from injury or alter Evans Blue uptake by the 7-day thrombus. DNA synthesis measured in terms of [3H]thymidine incorporation into biochemical extractable DNA and expressed as dpm/mg DNA was 9 519 for the normal rabbit aortic wall without adventitia; 358 261 for myointimal thickenings including underlying aortic wall without estradiol treatment and 196 336 with estradiol; 55 840 for thrombus without estradiol and 55 250 with estradiol. Expressed as dpm/mg delipidated tissue the values were 62 for the normal rabbit aortic wall; 4 590 for myointimal thickenings without estradiol and 2 037 with estradiol; 1 421 for thrombus without estradiol and 1 403 with estradiol. Estradiol was effective in reducing DNA synthesis in the myointimal thickenings from injury but was not effective in reducing DNA synthesis in the 7-day thrombi. Estradiol significantly increased the influx or retention of [14C]cholesterol found at autopsy in both the organizing thrombi and the myointimal thickenings from injury after an oral dose of 14C-labelled cholesterol was administered 4 days prior to autopsy; however, estradiol did not significantly modify the final cholesterol concentration in the lesions.