Electrocardiographic abnormalities in rats by acute exposure to nitrogen dioxide

Changes in cardiac function of rats acutely exposed to nitrogen dioxide (NO2) were examined by electrocardiographic (ECG) records. Bradycardia and arrhythmia which were observed by exposure to 20 ppm NO2 or more for 3 h were abolished by injection of atropine sulfate. ECGs were recorded following experimental formation of nitrite (NO-2) and nitrate (NO-3) in blood of normal rats by administration of NaNO2 solution, but no remarkable changes were observed on ECG. These results suggest that abnormal cardiac function observed during acute exposure to NO2 is attributable to changes in parasympathetic nervous activity and not to elevated NO2- and NO3- concentration in blood.