title: Not Ca2+ but CAMP is the second messenger for morphological changes in rat megakaryocyte.
abstract: ATP and thrombin both induced Ca2+ mobilization from intracellular Ca2+ store site of megakaryocyte, the progenitor cell of platelet (Uneyama C., Uneyama H. and Akaike N. (1993) J. Physiol. (Lond.), 470, 73-749). Since in platelet, thrombin is known as a strong agonist and ADP is known as a weak agonist, we further investigated the effect of these agonists on megakaryocyte. Thrombin induced Ca2+ mobilization, 5-hydroxy tryptamine (5-HT) release and aggregatory morphological changes in megakaryocyte, but ATP induced only Ca2+ mobilization. Thrombin-induced 5-HT release was inhibited by adenylate cyclase-activating drugs, and the morphological changes could be induced by H-8, an inhibitor of cAMP-dependent protein kinase. These results suggest that the Ca2+ mobilization is not sufficient to induce morphological changes, and the signal to cause morphological changes in megakaryocyte may be cAMP.
authors.affiliation: Division of Pathology, National Institute of Health Sciences, Tokyo, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Uneyama
authors.forename: T
authors.initials: T
authors.lastname: Imazawa
authors.forename: H
authors.initials: H
authors.lastname: Uneyama
authors.forename: N
authors.initials: N
authors.lastname: Akaike
authors.forename: T
authors.initials: T
authors.lastname: Kawanishi
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001854:Bone Marrow Cells; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D005260:Female; D008297:Male; D008533:Megakaryocytes / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure*; D008564:Membrane Potentials / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D015221:Potassium Channels / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D015290:Second Messenger Systems; D012701:Serotonin / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology
chemical_list: D015221:Potassium Channels; D012701:Serotonin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D013917:Thrombin; D002118:Calcium