Clearance of [14C] polyamines from plasma and erythrocytes in the rat

The [14C] polyamines, putrescine, spermidine and spermine were administered intravenously to rats. Arterial blood samples were obtained 2, 4, 6, 12, 20, 30, 60 and 120 min. after injection. Plasma and erythrocyte fractions were separated and assayed for [14C] activity. The clearance of radiolabelled polyamines from both the plasma and erythrocytes was rapid. Within 10 min. of injection, plasma putrescine had decreased by 70%, spermine by 80% and spermidine by 85%. In the same time interval the erythrocyte putrescine level had decreased by 50%, spermine by 70% and spermidine by 80%. This data suggests that exogenously injected radiolabelled polyamines and presumably endogenously produced polyamines are rapidly cleared from the circulation.