Document Detail

Intracellular influx of calcium induced by quartz particles in alveolar macrophages.
MedLine Citation:
PMID:  19835900     Owner:  NLM     Status:  MEDLINE    
Historical studies report that cellular injury and silicosis are related to cytosolic free calcium (Ca2+). Moreover, reactive oxygen species (ROS) have been linked to cellular injury. However, the detail mechanism of the increase in [Ca2+]i and the relationship between [Ca2+]i and ROS production remains unknown. Quartz particle has been found to increase [Ca2+]i and activate the generation of ROS. Our hypothesis is that [Ca2+]i increase induced by quartz particle is from extracellular Ca2+ through the Ca2+ channel, and [Ca2+]i increase is believed to activate ROS production. In order to examine this hypothesis, we treated rat alveolar macrophages with quartz (SiO2) particles and used laser scanning confocal microscopy to measure [Ca2+]i and the fluorescence intensity of ROS. Time- and dose-dependent increases in [Ca2+]I and ROS in macrophages as well as cell viability were observed. Through chelating extracellular Ca2+ with ethylene glycol tetraacetic acid and releasing intracellular Ca2+ with thapsigargin, we found that 72.7% of the [Ca2+]i increase was due to the influx of Ca2+ from the extracellular environment, via Ca2+ channels in the plasma membrane. By adding mannitol to scavenge hydroxyl radicals (OH(.)), and removing surface iron from the quartz particles to reduce OH(.) generation, we observed a reduced level of ROS generation, whereas the increase in [Ca2+]i was unaffected. When using EGTA to reduce [Ca2+]i, we observed a decrease in ROS production. This study suggests that the [Ca2+]i influx was independent of OH(.) production, and the [Ca2+]i increase resulted in ROS production. These results further indicate that there is a strong relationship between cytosolic free Ca2+ content and cellular injury as well as silica exposure.
Feng Tian; Tong Zhu; Yu Shang
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-10-14
Journal Detail:
Title:  Toxicology and applied pharmacology     Volume:  242     ISSN:  1096-0333     ISO Abbreviation:  Toxicol. Appl. Pharmacol.     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2009-12-07     Completed Date:  2009-12-15     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0416575     Medline TA:  Toxicol Appl Pharmacol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  173-81     Citation Subset:  IM    
State Key Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
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MeSH Terms
Bronchoalveolar Lavage Fluid
Calcium / metabolism*
Ion Transport
Macrophages, Alveolar / metabolism*
Rats, Sprague-Dawley
Reactive Oxygen Species / metabolism
Reg. No./Substance:
0/Reactive Oxygen Species; 14808-60-7/Quartz; 7440-70-2/Calcium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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