Increase in blood serotonin levels in the hepatic venous outflow after intraportal tumour cell injection.

An important role of platelet-liberated serotonin (5-HT) for the hepatic lodgement of intraportally injected tumor cells was suggested in previous studies. In the present investigation the inferior caval vein was cannulated for determination of 5-HT levels in the hepatic venous outflow in association with tumour cell lodgement in the liver. A peak of 5-HT could be demonstrated in the inferior caval vein 15 min after intraportal tumour cell injection, indicating exposition of the liver to high local concentrations of 5-HT in excess of the metabolizing capacity of the liver, associated with tumour cell lodgement.