Dextran-induced release of serotonin from isolated rat peritoneal mast cells.

Dextran (9 mg/ml incubate) was found to induce a serotonin (5-HT) release from isolated rat peritoneal mast cells of about 10% within an incubation period of 5 min. at 37 degrees. The extent of release was not increased by using higher concentrations of dextran or by increasing the incubation period from 5 to 20 min. The dextran-induced release of 5-HT was increased to 50-60% when the mast cells were preincubated with phosphatidylserine (PS) in doses of 2.6-4.3 microgram/ml incubate. Higher concentrations of PS alone induced a rapid 5-HT release of approximately 50-60%. The 5-HT release process studied was found to possess both similarities and dissimilarities with the previously described dextran-induced release process of histamine, also studied in isolated rat peritoneal mast cells. The results supported previous indirect evidence of a 5-HT release from mast cells in the early phase of the dextran-induced anaphylactoid reaction in the rat.