Exposure to real ambient particulate matter inflicts cardiac electrophysiological disturbances, vascular calcification, and mitochondrial bioenergetics decline more than diesel particulate matter: consequential impact on myocardial ischemia-reperfusion injury.

Abstract

Particulate matter (PM) present in the air sample comprises different sizes and is derived from multiple sources, in particular from diesel engines. In the present study, we assessed the cardiotoxic effect of PM2.5 from real ambient air sample and diesel vehicular exhaust from a specific location and compared it with SRM-2975. Female Wistar rats were exposed to PM2.5 from real ambient PM (RA_PM), diesel particulate matter (DPM), and SRM-2975 for 3h daily for 21 days followed by cardiotoxicity assessment. Twenty-one days of daily PM2.5 exposure induced hypertrophy, vascular calcification, and alterations in cardiac electrophysiology, where the changes were more prominent in the animals exposed to RA_PM. The gross pathological changes were supported by altered mitochondrial function and increased oxidative stress in the myocardium. To evaluate the cardiac responsive ability, isolated rat hearts were subjected to ischemia-reperfusion injury (IR), and the results showed significantly low recovery in the RA_PM-exposed rat hearts. Chemical analysis of PM2.5 by ICPMS from different sources indicated the presence of additional metals like Cr, Ni, Ga, As, Rb, Cd, Ba, La, and Ce in the RA_PM sample. Additionally, the chelation of metals in the RA_PM enhanced the cell viability of H9c2 cells when compared to the non-chelated sample. Based on the above observations, we conclude that PM2.5 from the ambient air sample exhibited higher cardiovascular toxicity than DPM, emphasizing the contribution of non-diesel components of PM2.5 and the need for a comprehensive approach to tackle the PM2.5 in the air sample.