Serotonin as a factor in depression of collateral blood flow following experimental arterial thrombosis.

: The relationship of serotonin to the inhibition of collateral blood flow was investigated. Five cats, in which the aorta contained a 6 microgram injection of serotonin in a closed aortic segment exhibited depressed hindlimb blood flow. The serotonin effects were eliminated in three animals by pretreatment with cinarserin HCl, a serotonin antagonist. The caudal 1.5 cm of the aorta was occluded in 24 cats by a blood clot formed by injection of thromboplastin subsequent to ligation. Eight of these animals were pretreated with cinanserin HCl and exhibited a significant improvement in hindlimb collateral blood flow. Serotonin was reduced in nine of these animals with reserpine/p-CPA treatment, and they exhibited the most significant recovery of all treated animals. Seven of the cats with blood serotonin reduced by decreasing blood platelets showed no improvement in hindlimb blood flow. The results of this study indicate that serotonin is a factor in the inhibition of collateral blood flow which follows arterial thrombosis.