Reduction of platelet serotonin and the response to pulmonary emboli.

Abstract

At is believed that vasoactive amines released by thrombin from the platelet coating of emboli play an important role in determining the magnitude of the vascular response to pulmonary emboli.gv 21n z3 As early as 1953, it was suggested that serotonin (5hydroxytryptamine, 5-HT) might be the agent responsible for the reflex and direct cardiopulmonary changes associated with pulmonary emboli.lp I2 A wide variety of experimental approaches utilizing synthetic emboli were undertaken but conflicting data and conclusions resulted. Gradually, and in a variety of species, subsequent investigators have demonstrated, with the use of fresh thromboemboli, the importance of humoral factors derived from platelets in pulmonary embolism.*> 11~ I7 It has been shown that they are responsible for vascular and airway constriction and contribute to the mortality rate caused by pulmonary embolism.7v Is, x These animal models demonstrate a pathophysiological sequence similar to that which is often encountered clinically. More recently, during the course of some of this work, we observed that rabbits obtained from two different sources responded to pulmonary emboli in dissimilar fashion.lG Inquiry revealed that animals showing relatively little vascular response to the embolus