Measurement of ionized cytoplasmic calcium mobilization with the photoprotein aequorin in human polymorphonuclear leukocytes activated by platelet activating factor (PAF).
The use of the sensitive photoprotein aequorin as a Ca2+ indicator in human polymorphonuclear leukocytes (PMN) not pretreated with cytochalasin B and stimulated with platelet activating factor (PAF) may help cast more light on the relative importance of intracellular and extracellular Ca2+ in PMN function. PAF elicits Ca2+ mobilization in PMN (resuspended in the presence of 1 mM extracellular Ca2+), in a concentration-dependent manner. The Ca2+ chelator ethyleneglycoltetraacetic acid (EGTA) abolishes Ca2+ mobilization, suggesting that almost all Ca2+ mobilized by PAF derives from the external medium. Aggregation and enzymatic release parallel the Ca2+ mobilization triggered by PAF. In contrast PAF appears to be only a weak stimulus of superoxide anion production (compared to the phorbol ester phorbol 12-myristate 13-acetate (PMA] and leukotriene B4 (LTB4) synthesis (compared to the Ca2+ ionophore A23187). The fact that PAF elicits Ca2+ mobilization, aggregation, secretion and LTB4 generation in human PMN supports the role of this phospholipid as a powerful mediator of physiopathological events involving PMN activation.
Del Maschio
A
A
Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Albors
M
M
Evangelista
V
V
Bucchi
F
F
Bertelé
V
V
Cerletti
C
C
de Gaetano
G
G
D000331:Aequorin / Q000008:administration & dosage / Q000378:metabolism; D002118:Calcium / Q000097:blood*; D002449:Cell Aggregation / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D005966:Glucuronidase / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007975:Leukotriene B4 / Q000097:blood; D009113:Muramidase / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism; D010972:Platelet Activating Factor / Q000494:pharmacology*; D013481:Superoxides / Q000097:blood
D010972:Platelet Activating Factor; D013481:Superoxides; D007975:Leukotriene B4; D000331:Aequorin; D009113:Muramidase; D005966:Glucuronidase; D002118:Calcium