[Various aspects of the effect of heparin-serotonin complex on blood and blood flow].

High-molecular heparin-serotonin complex (3:1 weight ratio) was obtained in vitro. The complex, its components, and heparin-serotonin mixture were introduced intraperitoneally in rats, and the resulting effects were registered 10, 30, and 60 min later. The complex had anticoagulant and lytic activities distinct from those of plasmin. According to decrease activity of factor XIII and decreased concentration of fibrinogen, the complex stimulated the anticoagulant system. In addition, the heparin-serotonin complex penetrated the hematoencephalic barrier and decreased the rate of brain bloodstream. The observed physiological properties of the heparin-serotonin complex were distinct from those of serotonin, heparin, and their mixture.