Prevention of laser arterial thrombus formation with unfractionated heparin.

A method to induce microthrombi in small mesenteric arteries (30-40 microns) has been developed to study platelet reactions and to investigate antithrombotic drugs. This model was used to evaluate the effect of Ca-heparin. Mesenteric lesions are induced in the vascular system of Wistar rats with an argon laser. The laser induced the formation of vessel wall lesion with damage of endothelial cells. Thrombi formed within seconds after the laser lesion and grew rapidly. Embolization began within a minute following the laser flash. Thrombus formation and embolization were repetitive phenomena. The administration of Ca-heparin at different dosages (0.5, 1.0 and 2.0 mg/kg) increases the number of laser injuries required to induce thrombus formation, and dose-dependently decreases the number of emboli and the duration of embolization. The highest dose injected (2.0 mg/kg) induced the strongest reduction in the number of emboli and duration of embolization.