Abstract P299: Gender-Based Differences in Ozone-Induced Cardiac Dysfunction

Abstract

Sex related differences have been noted in cardiovascular disease where females have a lower incidence of heart failure, and a higher rate of heart failure survival. On-the-other-hand, some studies have reported increased mortality in women compared with men. Recent data also suggest that women have an increased risk of death due to O 3 air pollution, which is in contrast to reports that short-term variations in gaseous pollutants are associated with an increase in hospitalization for cardiac disease that is not modified by gender. It has been speculated that because of the nature of the photochemical equilibrium of O 3 in the ambient environment and due to other confounding factors epidemiological investigations of the health effects of O 3 may be using O 3 as an exposure surrogate for other oxidants or co-pollutants, some of which may be interfering with response to O 3 . The present study in a controlled exposure protocol tested the hypothesis that female rats compared to male have decreased sensitivity to cardiac injury subsequent to O 3 exposure. Age matched male/female rats were exposed 8 hrs/day for 28 and 56 days to filtered air or 0.8 ppm O 3 . In order to assess the chronic effects to O 3 , in-vivo cardiac function was assessed, 24 hrs after termination of the O 3 exposure. Compared to female rats, LVDP values significantly decreased in O 3 exposed male rats. This enhanced attenuation of cardiac function in male animals was associated with increased myocardial TNF-alpha (TNF-α) levels and decreased myocardial activities of superoxidase dismutase (SOD). These novel findings suggest that decreased attenuation of cardiac function in O 3 exposed females compared to males exposed to similar conditions was associated with decreased inflammatory mediator production and decreased oxidative stress. Identifying the underlying factors for gender based variations in ozone response is very important to recognize at-risk groups who would benefit from preventive strategies. In addition identification of those at risk, their degree of sensitivity will assist with the cost-benefit analysis of “safe” exposure levels in the public health setting. The long-term goal of this study is in guiding regulatory policies for reduced environmental related health costs.