Restoration of post-thrombotic peripheral collateral circulation in the cat by ketanserin, a selective 5-HT2-receptor antagonist.

In cats, an acute thrombotic obstruction of the aorta inducing continuous platelet activation, was produced by permanent ligation above the trifurcation, temporary ligation below the caudal mesenteric artery and production of a stasis thrombus in the segment. Before, 5 min, 24 hr and 48 hr after surgery, plethysmographic systolic blood pressure in fore- and hindlegs, and clinical scoring of the hindleg function were performed; at 72 hr, venous occlusion plethysmography for quantification of blood flow was performed and collateral vascular resistance was calculated. Thrombotic occlusion resulted in a loss of adequately functioning collateral circulation as evidence by the changes in both the objective and the clinical parameters. Pre-treatment with ketanserin (1.25 mg/kg i.p. daily) significantly improved the objective circulation parameters blood pressure ratio, blood flow and collateral vascular resistance and restored the clinically scored function of post-thrombotic collateral function. Provided platelet activation contributes to human vascular pathology, a similar mechanism may be involved in the potential effect of ketanserin in man.