PM2.5 induces acute electrocardiographic alterations in healthy rats

There is evidence that changes of the autonomic control of the heart are among the potential mechanisms responsible for pollution-related cardiac mortality. The objective of this work is to assess the acute effects of urban particulate matter of ⩽2.5 μm (PM2.5) particles on heart rate (HR) and HR variability. Forty-seven healthy Wistar rats were anesthetized, submitted to tracheal intubation, and instilled with 1 mL of four different solutions: saline, blank filter, and 50 or 100 μg of PM2.5. PM2.5 was collected in glass fiber filters using a high-volume sampler. Electrodes for obtaining electrocardiograms were implanted subcutaneously in a Lead II configuration. HR and the standard deviation of the intervals between normal beats (SDNN) were assessed immediately before and 30 and 60 min after instillation. HR decreased significantly (P<0.001) with time, but no significant effect of treatment or interaction between time and treatment was observed. In contrast, there was a significant SDNN interaction between time and treatment (P=0.025). The SDNN decreased 60 min after instillation with a PM2.5 of 50 and 100 μg. In conclusion, the injection of an aqueous suspension of PM2.5 induced a reduction of SDNN in healthy rats. The effect was observed 1 h after instillation and in a concentration of <100 μg.