Increased calcium influx in a monocytic cell line on exposure to ultrafine carbon black.
Ultrafine particles have been shown to induce pro-inflammatory effects both in vivo and in vitro. Increased expression of pro-inflammatory genes probably requires the activation of specific transcription factors such as nuclear factor kappa B (NF-kappaB) via a number of possible pathways including Ca2+ and reactive oxygen species. The fluorescent dye fura 2, was used to measure cytosolic Ca2+ in the human monocytic cell line, Monomac 6 on exposure to 66 microg x mL(-1) of either ultrafine carbon black (ufCB; diameter 14 nm), carbon black (CB; diameter 260 nm), quartz (diameter 1.45 microm), or medium alone. UfCB but not fine CB induced a 1.6-fold increase (p<0.01) in the resting cytosolic Ca2+ concentration of Monomac 6 cells. In addition ufCB induced a 2.6-fold increase (p<0.001) in the response to the endoplasmic reticulum Ca2+- adenosine triphosphatase (ATPase) inhibitor, thapsigargin, suggesting the Ca2+ release-activated Ca2+ current across the plasma membrane was enhanced. This response was inhibited by the removal of extracellular Ca2+ and by the Ca2+ channel blocker, verapamil. In addition, ufCB stimulated the entry of extracellular Mn2+. Finally, the antioxidants mannitol and nacystelin both inhibited the effects of ufCB on the response to thapsigargin. These data suggest that ultrafine carbon black particles stimulated an increase in cytosolic Ca2+, possibly through the entry of extracellular Ca2+ via Ca2+ channels in the plasma membrane. The particles may in part activate the opening of Ca2+ channels via a mechanism involving reactive oxygen species.
Stone
V
V
Dept of Biological Sciences, Napier University, Edinburgh, Scotland, UK.
Tuinman
M
M
Vamvakopoulos
J E
JE
Shaw
J
J
Brown
D
D
Petterson
S
S
Faux
S P
SP
Borm
P
P
MacNee
W
W
Michaelangeli
F
F
Donaldson
K
K
D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D002244:Carbon; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D005456:Fluorescent Dyes; D016257:Fura-2; D006801:Humans; D066298:In Vitro Techniques; D009000:Monocytes / Q000378:metabolism*; D010316:Particle Size; D019284:Thapsigargin / Q000494:pharmacology
D015220:Calcium Channels; D005456:Fluorescent Dyes; D019284:Thapsigargin; D002244:Carbon; D002118:Calcium; D016257:Fura-2