Pharmacological studies on mechanisms involved in Ca2+ oscillations in rat megakaryocytes.
Extracellular application of ATP evoked the oscillatory K+ currents (IKCa) reflecting oscillation in cytoplasmic Ca2+ concentration ([Ca2-]i) of megakaryocyte isolated from rat bone marrow. We have reported that the [Ca2+], oscillation was regulated by intracellular Ca(2+)-pumping activity (Uneyama H.C. Uneyama and N. Akaike, 1993, J. Biol. Chem. 268, 168). Here we found that the Ca2+ pump of the megakaryocyte could be divided into at least two classes according to the sensitivity to phosphorylation-modulating drugs. The effects of protein kinase C and cyclic AMP-dependent protein kinase are complementary, and the effect of Ca2+/calmodulin is independent of the above two kinases. In addition, this is the first report concerning the physiological regulation of Ca(2+)-ATPase in living cells.
Uneyama
C
C
Division of Pathology, National Institute of Health Sciences, Tokyo, Japan.
Uneyama
H
H
Takahashi
M
M
Akaike
N
N
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D005576:Colforsin / Q000494:pharmacology; D005260:Female; D007211:Indoles / Q000494:pharmacology; D008297:Male; D008533:Megakaryocytes / Q000187:drug effects*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D051381:Rats; D017208:Rats, Wistar; D019311:Staurosporine; D013449:Sulfonamides / Q000494:pharmacology; D013729:Terpenes / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin
D000470:Alkaloids; D002147:Calmodulin; D007211:Indoles; D013449:Sulfonamides; D013729:Terpenes; D005576:Colforsin; C017967:W 7; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D000252:Calcium-Transporting ATPases; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; C000543:cyclopiazonic acid