Increased cytosolic Ca(2+) concentration in endothelial cells by calmodulin antagonists.
Many functions of endothelial cells are Ca(2+)/calmodulin dependent, whereas the role of calmodulin in the regulation of cytosolic Ca(2+) ([Ca(2+)](i)) remains largely unexplained. In the present study, effects of various calmodulin antagonists on [Ca(2+)](i) were investigated in cultured aortic endothelial cells loaded with the Ca(2+)-sensitive dye fura-2/AM, and were compared with those of calmodulin-dependent protein kinase II (CaM kinase II) inhibitors. The calmodulin antagonists W-7, calmidazolium and fendiline provoked dose-dependent increases in [Ca(2+)](i). However, the CaM kinase II inhibitors KN-93 and lavendustin C had no effect on [Ca(2+)](i). In the absence of extracellular Ca(2+), pretreatment of cells with bradykinin (BK) and thapsigargin completely prevented W-7-stimulated increase in [Ca(2+)](i). Alternatively, pretreatment with W-7 also completely blocked BK- and thapsigargin-stimulated increases in [Ca(2+)](i). The time course of the Ca(2+)-response in W-7 treated cells was identical to that in thapsigargin-treated cells, but not that in BK-stimulated cells, suggesting that calmodulin antagonists could share a common signaling pathway with thapsigargin to increase [Ca(2+)](i) in endothelial cells. These findings indicate that calmodulin is involved in the regulation of [Ca(2+)](i), and may play an important role in the uptake of Ca(2+) to intracellular stores.
Watanabe
H
H
Department of Clinical Pharmacology and Therapeutics, Internal Medicine III, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu, 431-3192, Japan. hwat@hama-med.ac.jp
Takahashi
R
R
Tran
Q K
QK
Takeuchi
K
K
Kosuge
K
K
Satoh
H
H
Uehara
A
A
Terada
H
H
Hayashi
H
H
Ohno
R
R
Ohashi
K
K
D000818:Animals; D001596:Benzylamines / Q000494:pharmacology; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002147:Calmodulin / Q000037:antagonists & inhibitors*; D002478:Cells, Cultured; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005275:Fendiline / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007700:Kinetics; D008345:Manganese / Q000378:metabolism; D010636:Phenols / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013552:Swine; D019284:Thapsigargin / Q000494:pharmacology; D000096926:Benzenesulfonamides
D001596:Benzylamines; D001920:Bradykinin; D002118:Calcium; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002147:Calmodulin; D004791:Enzyme Inhibitors; D005275:Fendiline; D007093:Imidazoles; D008345:Manganese; D010636:Phenols; D013449:Sulfonamides; D019284:Thapsigargin; C072105:KN 93; D000096926:Benzenesulfonamides; C080022:lavendustin C6; C031938:calmidazolium; C017967:W 7