Not Ca2+ but CAMP is the second messenger for morphological changes in rat megakaryocyte.
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.
Uneyama
C
C
Division of Pathology, National Institute of Health Sciences, Tokyo, Japan.
Imazawa
T
T
Uneyama
H
H
Akaike
N
N
Kawanishi
T
T
Takahashi
M
M
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
D015221:Potassium Channels; D012701:Serotonin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D013917:Thrombin; D002118:Calcium