The Filter Loop Technique as a Method of Measuring Platelet Aggregation in the Flowing Blood of the Rat; the Inhibitory Activity of 5-oxo-l-cyclopentene-l-heptanoic Acid (AY-16,804) on Platelet Aggregation^[*]

Summary

The filter loop technique which measures platelet aggregation in vivo in the flowing-blood of the rat was compared to the optical density technique of Born which is carried out in vitro with platelet rich plasma. Using these two experimental models the effect on platelet aggregation of three known inhibitors sulfinpyrazone, dipyridamole and prostaglandin E₁, and a novel compound 5-oxo-l-cyclopentene-l-heptanoic acid (AY-16, 804) was determined.

The effects on platelet aggregation of the known inhibitors were consistent with information in the literature. Prostaglandin E₁ was the most potent inhibitor in both techniques; sulfinpyrazone inhibited aggregation in both models but was less potent than prostaglandin E₁. AY-16, 804 exhibited activity in vitro and in vivo similar to that of sulfinpyrazone. Dipyridamole did not inhibit platelet aggregation in vivo and did not inhibit aggregation in vitro in concentrations at which it remained soluble.

The filter loop technique is a suitable model for measuring platelet aggregation in the flowing blood of the rat. It is a relatively simple method of determining aggregation and easily adapted to other species.

^* Presented in part at the 56th Annual Meeting of the Federation of American Societies for Experimental Biology, Atlantic City, N. J., April 9-14, 1972.

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