Transient increase of cytosolic free calcium in cultured human vascular endothelial cells by platelet-activating factor.
The effect of platelet-activating factor (PAF-acether) on cytosolic free calcium, [Ca2+]i, in adherent human vascular endothelial cells in culture was directly determined using a new fluorescent calcium indicator, fura-2. It was found that PAF-acether but not lyso PAF-acether induced a rapid and transient increase in [Ca2+]i in endothelial cells. Restimulation with PAF-acether after the first challenge did not cause further response, while the cells were able to respond to thrombin. In the absence of extracellular calcium, PAF-acether evoked a similar transient increase, suggesting that PAF-acether raises [Ca2+]i mainly by discharging calcium from intracellular pools. PAF-acether-induced rise in [Ca2+]i was completely blocked by a specific antagonist, BN 52021. These results suggest the receptor-mediated increase in [Ca2+]i as an early event in PAF-acether activation of human vascular endothelial cells.
Hirafuji
M
M
Department of Pharmacology I, Tohoku University School of Medicine, Sendai, Japan.
Maeyama
K
K
Watanabe
T
T
Ogura
Y
Y
D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D010972:Platelet Activating Factor / Q000502:physiology*; D011247:Pregnancy; D013917:Thrombin / Q000502:physiology; D014471:Umbilical Veins
D010972:Platelet Activating Factor; D013917:Thrombin; D002118:Calcium