Studies on megakaryocytes: isolation from rat and guinea pig and incorporation of 5-hydroxytryptamine

A new, two step method is described for the isolation of megakaryocytes from bone marrow. By means of centrifugation in a PercollR density gradient megakaryocytes can be enriched by factor 68 or 24 starting from rat or guinea pig bone marrow, respectively. The purity of the megakaryocytes can be improved ca. 4 fold if gradient centrifugation is followed by separation in an Elutriator rotor.-The isolated megakaryocytes take up exogenous 5-hydroxytryptamine with a time and concentration dependent transport mechanism, K11=30 micrometer, K12=1.5 micrometer. As shown by electron microscopy the number and density of storage granules within the megakaryocytes is enhanced after incubation with 5-hydroxytryptamine. This finding suggests that 5-hydroxytryptamine is incorporated into the organelles.