Reactions of rat megakaryocytes in mixed cell suspension.

Rat megakaryocytes in mixed bone marrow cell suspension underwent mor­ phologic change when exposed to adenosine diphosphate (ADP) and epi­ nephrine. Viewed by phase microscopy, marginal membranes developed ragged or vacuolated appearance within one minute after exposure to ADP or epinephrine. Recovery from the change induced by ADP occurred within five minutes. These effects were inhibited by prior incubation of the cell sus­ pension with dibutyryl adenosine cyclic monophosphate (DBcAMP) and were not produced by adenosine monophosphate (AMP) or adenosine triphosphate (ATP). The results suggest that megakaryocyte membranes react with agents known to effect platelets and lend support to the indications that demarcating membranes of megakaryocytes derive from the megakaryocyte plasma mem­ brane. No observations were made which relate these observed changes to the release of platelets from megakaryocytes.