Intracellular distribution of adenine and 5-hydroxytryptamine in megakaryocytes isolated by density gradient and velocity sedimentation from bone marrow.

Megakaryocytes were isolated from rat and guinea pig bone marrow by Percoll density and/or elutriator centrifugation. As compared with the suspension of bone marrow an enrichment of factor 530 with a recovery of 34% can be achieved if a combination of both methods is applied.--The pattern of DNA percentage distribution in isolated cells paralleled the polyploidy found in megakaryocytes of the bone marrow. As determined by scanning cytophotometry and impulse cytophotometry the percentage distribution was maximal for the 16 C cells.--Exogenous [3H]adenine was incorporated by isolated megakaryocytes via a time and concentration dependent process showing two different affinities, Kt1 = 11 nM, V1 = 0.07 pmol/min per 10(5) cells; Kt2 = nM, V2 = 0.21 pmol/min per 10(5) cells.--Autoradiographic studies quantificated by means of the "probability circle" and "percent density" analysis showed that [3H]5-hydroxytryptamine (5-HT) accumulated in the osmiophilic dense bodies in contrast to [3H]adenine (metabolite) which was found mainly in the cytoplasm.