Simulated vehicle exhaust exposure (SVEE) in rats impairs renal mitochondrial function

Abstract

Purpose Vehicle exhaust emissions primarily comprise of nitrogen, oxygen, water, CO2, NO2, CO, hydrocarbons and particulate matter. While adverse effects of hydrocarbon and particulate matter on cardiovascular functions are known, the effect of pro-oxidants CO2, NO2 and CO are not clear. Methods Here, using an animal model of a simulated mixture of pro-oxidants (0.04% CO2, 0.9 ppm NO2 and 3 ppm CO with air as a base), we examined the effect of simulated vehicle exhaust exposure (SVEE) on various cardiovascular parameters. Male Sprague-Dawley rats were exposed to SVEE or ambient air (Control: CON) for 30 min/day for 2 weeks. Thereafter, systolic and diastolic blood pressure, heart rate and glomerular filtration rate were measured. Later, rats were sacrificed, blood plasma and kidneys were collected. Results The systolic and diastolic blood pressure, heart rate and glomerular filtration rate remained unchanged. Plasma corticosterone increased in SVEE rats when compared to CON group. Plasma 8-isoprostane, a systemic marker of oxidative stress, increased while total antioxidant capacity decreased in SVEE but not in CON. Kidney cortical tissue homogenates exhibited increase in superoxide, hydrogen peroxide and protein carbonylation in SVEE but not CON, all indicative of heightened oxidative stress. Renal cortical mitochondrial SOD activity was significantly reduced in SVEE than CON. Conclusion Significant decline in mitochondrial respiration and oxygen consumption was observed, in addition to low ATP, reduced ATP synthase and cytochrome C oxidase levels, as well as accelerated mitochondrial fission, and reduced fusion processes, were observed in SVEE than CON rats, all indicative of renal mitochondrial impairment.

Keywords

• vehicle exhaust
• air pollution
• kidney
• mitochondria
• oxidative stress