ABSTRACT
The reason that paraquat selectively damages the lung is that the chemical utilises an energy-dependent system normally involved in diamine and/or polyamine uptake; concentrations of paraquat in lung increase with time and are many times those in plasma and other tissues. The high concentrations achieved in vivo and in the in vitro slice experiments are average concentrations in the whole tissue. However, the damage is not uniform in all cells and the morphological changes begin in the types 1 and 2 epithelial cells. It is now known that these cells possess the transport system for both paraquat and putrescine. Since these cells are a small proportion of the total lung cell population the concentration of paraquat in these cells will be correspondingly higher.
