Effects of Diesel Exhaust Particles on Left Ventricular Function in Isoproterenol-Induced Myocardial Injury and Healthy Rats

Abstract

The associations between ambient particulate matter with an aerodiameter less than 2.5 μ m (PM_2.5) and congestive heart failure (CHF) have been reported. However, the underlying mechanisms remain unclear. We investigated the effect of diesel exhaust particles (DEPs) on left ventricular function in isoproterenol (ISO)-induced myocardial injury and healthy rats. Male Sprague-Dawley (SD) rats were injected with ISO or normal saline. Seven days later, both groups were further assigned to receive either DEPs or normal saline by intratracheal instillation (IT). Echocardiography was used to measure fractional shortening (FS) and left ventricular end-diastolic diameter (LVDd) 24 h before and after IT in each rat. Fractional shortening (FS) was significantly decreased in SD rats treated with ISO as compared to those treated with normal saline (p < .05, t-test). When FS and LVDd before and after treatment were compared in each rat, there was no difference for normal saline treatment in healthy or ISO groups. However, there was significantly lower FS before and after DEPs exposure in both groups (p < .05, paired t-test). When using SD rats treated with normal saline as a reference group, both SD rats treated with DEPs and ISO rats treated with normal saline had lower FS (p < .05 and.0001, respectively, t-test), while ISO rats treated with DEPs had the lowest FS (p < .0001, t-test). Echocardiographic assessment revealed that left ventricular function was impaired by acute DEPs exposure, and this LV function was further compromised in rats with preexisting ISO-induced myocardial injury.