Cardio-respiratory effects of paraquat with and without emetics on Wistar rats.

We investigated the effects of paraquat products both containing and devoid of emetics on the cardio-respiratory functions of Wister rats. Anesthetized rats were administered intravenously 0.46 ml/kg Gramoxone, a commercial product containing 24% paraquat and an emetic. Paraquat equivalence equalled 110 mg/kg body weight. ECG and respiratory curves were recorded with a polygraph. Fifteen seconds after injection, A-V block and bradycardia occurred and the heart stopped beating soon after. Though the heart was severely affected, the respiratory curve differed very little from pre-injection values. Administration of pure, 24% paraquat solution (110 mg/kg body weight) inhibited respiration and almost no change was recorded by the ECG. Administration of Paragreen A, a commercial product containing 24% paraquat with no emetic, produced slight change in the ECG but respiration soon became strained and stopped. In accordance with this data, we propose that the emetic contained in Gramoxone is primarily responsible for the cardiovascular failure.