Concentration-dependent effects of reductive pulmonary inhalants on ultrafine particle-induced oxidative stress: Insights for health risk assessment

The impact of reductive pulmonary inhalants on ultrafine particles (UFPs)-induced pulmonary oxidative stress remains a crucial consideration, yet the concentration-dependent effects of these inhalants have remained unexplored. Here we synthesized composite UFPs simulating atmospheric UFPs, primarily composed of metals and quinones. We subjected these UFPs to varying concentrations (0-7000 mu M) of two reductive pulmonary inhalants, N-acetylcysteine and salbutamol, to assess their influence on oxidative potential, measured through the dithiothreitol assay (OPDTT). Simultaneously, we analysed the soluble metal content of UFPs to uncover potential relationships between oxidative potential and metal solubility. Our results unveil a dual role played by these inhalants in shaping the OPDTT of composite UFPs. Specifically, OPDTT generally increased as inhalant concentrations rose from 0 to 300 mu M. However, an intriguing reversal occurred when concentrations exceeded 500 mu M, resulting in a decline in OPDTT. Relative to untreated UFPs, these inhalants induced promotion and inhibition effects within concentration ranges of 100-500 and >1000 mu M, respectively. While no significant correlation emerged between OPDTT and soluble metal content as inhalant concentrations ranged from 0 to 7000 mu M, noteworthy positive correlations emerged at lower inhalant concentrations (e.g., N-acetylcysteine at 0-300 mu M). These findings provide insights into the potential influence of reductive pulmonary inhalants on health risks associated with UFP exposure, further underscoring the need for continued research in this critical area.

Automated summary

This study investigates the impact of reductive pulmonary inhalants on pulmonary oxidative stress induced by ultrafine particles (UFPs). The results reveal a dual role played by these inhalants in shaping the oxidative potential of composite UFPs, with both promotion and inhibition effects observed.