Cytosolic calcium mobilization and thromboxane synthesis in a human megakaryocytic leukemia cell.
The functional and biochemical characteristics of human megakaryocytic leukemia cells remain unclear. In this study, we examined cytosolic Ca2+ ([Ca2+]i) mobilization and thromboxane (TX) formation in a megakaryocytic leukemia cell line, designated CMK. Stimulation of CMK cells with thrombin resulted in an increase of [Ca2+]i as measured with the fluorescent marker Fura 2-AM. The rise in [Ca2+]i was mostly dependent on extracellular Ca2+. Prostaglandin E1 (PGE1) further increased [Ca2+]i after thrombin addition, thus indicating that PGE1 had a different action on [Ca2+]i in cells of the platelet-megakaryocyte lineage. The addition of thrombin and the calcium ionophore A23178 to CMK cells caused similar rapid formations of TXB2 as measured by RIA. Thrombin plus A23178 had a synergistic effect on TXB2 synthesis in CMK cells. Thrombin had no effect of TX metabolism in the cells with myeloid, erythroid, B-lymphoid, and T-lymphoid lineages. These results indicate that thrombin-induced TX synthesis may serve as a marker of immature megakaryocytes.
Ryo
R
R
Blood Transfusion Service, Kobe University Hospital, Japan.
Yoshida
A
A
Adachi
M
M
Sugano
W
W
Yasunaga
M
M
Yoneda
N
N
Yamaguchi
N
N
Sato
T
T
D000527:Alprostadil / Q000494:pharmacology; D000911:Antibodies, Monoclonal; D001692:Biological Transport; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism*; D006801:Humans; D009994:Osmolar Concentration; D013917:Thrombin / Q000494:pharmacology; D013920:Thrombocythemia, Essential / Q000378:metabolism*; D013929:Thromboxane B2 / Q000096:biosynthesis*; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000001:Calcimycin; D013929:Thromboxane B2; D013917:Thrombin; D000527:Alprostadil; D002118:Calcium