Adverse Impact of Ambient Particulate Matter on Cardiac Electrophysiology and the Lipid Profile in Rats

Background: Particulate matter (PM) is an organic and inorganic mixture of particles of different sizes and chemical compositions. Positive correlations exist between the concentrations of air PM and respiratory and cardiovascular disorders, causing premature mortality and morbidity. This study was designed to evaluate the effects of PM on cardiac electrophysiology and the lipid profile in rats.   Methods: A total of 72 male Wistar rats (250–300 g) were divided into 6 groups: control (intratracheal instillation of 0.1-mL normal saline), PMA (intratracheal instillation of 0.5-mg/kg particles less than 10 μm [PM10]), PMB (intratracheal instillation of 2.5-mg/kg PM10), PMC (intratracheal instillation of 5-mg/kg PM10) twice at 48-hour intervals, calcium chloride (CaCl2) (140 mg/kg, intravenous), and isoproterenol (100 mg/kg, subcutaneous). After 48 hours, lead II electrocardiography was recorded and the inotropic and chronotropic properties of the heart and the incidence of arrhythmias were evaluated. Cardiac lipid parameters, including plasma cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides, and cardiac markers of myocardial infarction, creatine kinase-MB (CK-MB), and lactate dehydrogenase (LDH) were measured.   Results: After the administration of PM10, there was a significant decrease in the voltage of the QRS complex and the R-R interval in comparison with the control group. There was a significant increase in the number of arrhythmias (premature ventricular contractions, ventricular tachycardia, and ventricular fibrillation) after PM10 administration. The administration of PM10 led to an increase in LDL, cholesterol, triglycerides, LDH, and CK-MB and a decrease in HDL in all the concentration groups.   Conclusions: PM10 can be introduced as an arrhythmogenic agent with the potential to affect the cardiac lipid profile by inducing cardiac damage and infarction. (Iranian Heart Journal 2021; 22(1): 33-41)