Inhibition of gap-junctional intercellular communication by outdoor and indoor airborne particulate matter

The inhibition of gap-junctional intercellular communication (GJIC) by different airborne particulate matter (APM) extracts was tested in V79 cells and in primary cultures of alveolar type II cells. The results show that extracts of APM were able to inhibit GJIC in V79 and in alveolar type II cells at non-cytotoxic doses. Chemical fractionation of extracts showed that the neutral fractions accounted for most of the inhibitory activity on GJIC. The activities of basic and acid fractions was less than 5% of the total activity. Polycyclic aromatic hydrocarbons and nitrated derivatives are unlikely to be responsible for the activity of the neutral fractions, because several representatives of these compounds failed to inhibit GJIC. Taken together, these results suggest that extracts of APM, in addition to the genotoxic activity that has been known for many years, also have a tumor promoting activity.