Isolation of Dense Bodies from Human Blood Platelets Using Discontinuous Metrizamide Gradients

Abstract

Functionally active dense bodies (5-HT storage organelles) have been isolated from human platelets following centrifugation of platelet lysates on a two step discontinuous metrizamide gradient. Their purification was followed using platelets loaded with either (i) [14C]-5HT or (ii) mepacrine, a fluorescent dye selectively accumulated by the dense bodies. The isolated granules gave the typical appearance of dense bodies when examined by electron microscopy and were able to rapidly incorporate 5-HT; this incorporation was unaffected by imipramine but was strongly inhibited by reserpine.