Correction by ketanserin of the platelet-mediated inhibition of peripheral collateral circulation in the cat: Measurement of blood flow with radioactive microspheres

Platelets, activated to release vasoactive mediators on a stasis thrombus in the inferior aorta of the cat proximally from a mechanical ligation, induced a loss of collateral tissue perfusion in the hindlegs. Blood platelet number, platelet‐bound 5‐hydroxytryptamine, and plasma levels of 5‐hydroxy‐indoles, thromboxane B2 and 6K‐PGF1α did not differ significantly when measured in systemic arterial blood and in venous blood sampled distally from the stasis thrombus. The platelet‐mediated defect in the function of the collateral circulation in the periphery was corrected by ketanserin. This correction was evidenced by objective parameters such as blood pressure ratios and blood flow rates determined both by plethysmography and by radioactive microsphere measurements of regional tissue perfusion of skeletal muscles. This study demonstrated a predominant role for 5‐hydroxytrytamine in the platelet‐mediated inhibition of peripheral collateral circulation.