The accumulation of diamines and polyamines into rat lung slices

The diamine cadaverine, and the polyamines spermidine and spermine have been shown to accumulate into rat lung slices by an uptake process which obeyed saturation kinetics. The apparent K_m values for the accumulation process of cadaverine, spermidine and spermine were 19, 11 and 15 μM respectively with V_max values of 937, 768 and 617 nmoles/g wet weight/hr respectively. The accumulation was KCN sensitive, indicative of an energy dependent process, although spermine did show some non-specific binding to lung tissue. Cadaverine, spermidine and spermine were not accumulated by slices of liver, kidney, heart and spleen to concentrations much greater than that in the medium. They were accumulated, however, by a KCN sensitive process into brain slices although the accumulation was much less than that which occurred in lung slices. The diamine, putrescine, exhibited a concentration-dependent inhibition of the ability of lung slices to accumulate cadaverine and the polyamines. These data have led us to conclude that the transport process in the lung, which has recently been shown to accumulate the diamine putrescine, is also capable of accumulating cadaverine, spermidine and spermine. Thus, by analogy with putrescine, there exists in specific lung cells a membrane receptor(s) which is selective in its acceptance and transport of diamines and polyamines.