Initial accumulation of paraquat in the heart leading to acute death

When a large amount of paraquat (364 mg/kg) which caused death in several hours was orally ingested in rats, the herbicide concentration in blood continued to increase until the animal died. Furthermore, there was a correlation between the paraquat concentration in the blood, heart, liver and adrenal gland and the survival time. While the paraquat concentration in the heart had the most evident correlation in those tissues (r = -0.962), there was no correlation between the paraquat concentration and survival time in the lung or kidney. ECG of the rats which died in the early stages showed severe damage in the heart. It was found by histopathological studies that edema, congestion and hemorrhage occurred in the myocardium of rats that had died shortly after administration of a large amount of paraquat (364 mg/kg). These results suggest that a rapid accumulation of paraquat into the heart in the early stages may play an important role in the cause of acute death.