Paraquat and putrescine uptake by lung slices of fetal and newborn rats.

Paraquat is actively taken up by lung slices of mature rats. This uptake seems to occur primarily in the pneumocyte type II cells, and evidence suggests that these cells utilize an active transport system for putrescine to accumulate paraquat. We evaluated the uptake of paraquat and putrescine in lung slices of fetal and newborn rats. An active transport of paraquat and putrescine into lung slices was noted on day 20 of gestation. Putrescine and paraquat accumulation in lung slices increased thereafter and approached concentrations found in adult lung slices by the 2nd and 3rd postnatal week, respectively. Paraquat and putrescine inhibit accumulation of one another by lung slices of fetal rats.