AbstractThe susceptibility of the cardiovascular system to exposure to a high‐boiling coal liquid (heavy distillate, HD) was studied in the rat using an isoproterenol (ISO) myocardial infarction model. Male Fischer rats were exposed to HD by inhalation (0.7 mg/l), 6 h/day, 5 days/week, for 6 weeks. After a 10‐day recovery period, sham‐exposed and HD‐exposed rats were injected subcutaneously with 0, 20, 40 or 60 mg ISO/kg body weight. Blood pressure, heart rate, electrocardiogram and99mTc uptake by the heart were measured 1 day later. A dose‐related increase was observed in the uptake of99mTc by the hearts of both sham‐exposed and HD‐exposed animals after ISO injection; however, uptake by the sham‐exposed group was significantly greater than that of exposed groups. The most striking observation was a 20% elevation in arterial blood pressure of HD‐exposed rats over that of sham‐exposed animals when no ISO was injected. These results suggest that the cardiovascular system could be detrimentally affected by exposure to coal‐derived complex mixtures and, possibly, to other com