RESUMO
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 µM) 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 µM. However, an intriguing reversal occurred when concentrations exceeded 500 µM, 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 µM, respectively. While no significant correlation emerged between OPDTT and soluble metal content as inhalant concentrations ranged from 0 to 7000 µM, noteworthy positive correlations emerged at lower inhalant concentrations (e.g., N-acetylcysteine at 0-300 µM). 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.