Increased calcium influx in a monocytic cell line on exposure to ultrafine carbon black

Eur Respir J. 2000 Feb;15(2):297-303. doi: 10.1034/j.1399-3003.2000.15b13.x.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / metabolism*
  • Calcium Channels / drug effects
  • Calcium Channels / physiology
  • Carbon*
  • Cell Line
  • Cytosol / metabolism
  • Fluorescent Dyes
  • Fura-2
  • Humans
  • In Vitro Techniques
  • Monocytes / metabolism*
  • Particle Size
  • Thapsigargin / pharmacology

Substances

  • Calcium Channels
  • Fluorescent Dyes
  • Thapsigargin
  • Carbon
  • Calcium
  • Fura-2