Accumulation of radionuclide-labeled platelets and fibrinogen in paraquat-damaged rat lungs.

After intraperitoneal injection of paraquat, rats showed evidence of neurologic and respiratory damage and had a mortality rate of 41% in 3 days. The lungs quadrupled in weight between the third and the fifth day. Pulmonary edema and extravascular fibrin and platelets were identified by light and transmission electron microscopy. As early as 4 h after injection of the paraquat, 51Cr from labeled platelets began accumulating in the lungs. The peak was reached by 48 h; 125I from labeled fibrinogen also concentrated in the lungs of treated rats. Total complement was unchanged. The paraquat-treated rat is a suitable model for study of the behavior of fibrin and platelets in permeability pulmonary edema. Disturbances of copper metabolism deserve further investigation.