Summary
Characteristics of thrombi produced upon electrical stimulation of mesentery and brain vessels were studied in five species. Parameters for measuring drug effects were also evaluated to determine which were sensitive to platelet aggregation inhibitors. The current required to cause vasoconstriction in 50% of the rat mesentery arteries stimulated was increased by vasodilators, but not by inhibitors of platelet aggregation. The threshold of current necessary to cause thrombus formation was increased by Imipramine in both acute and chronic experiments and by aspirin and papaverine in chronic experiments. Since these were the only agents tested which inhibit platelet aggregation there appears to be a relationship between this property and the threshold of current necessary to cause thrombus formation. This parameter may possibly be used to differentiate between platelet aggregation inhibitors and streptokinase-like or heparin-like agents. Changes in mean embolization time under present conditions were not related to activity in inhibiting platelet aggregation.
