Transport of nitrullin,a new nitrosoalkylurea derivative,into tumor and normal cells

The interaction between the antitumor drug nitrullin and the system providing the transport ofl-lysine into P388 leukemic cells and murine enterocytes is studied. Two types of lysine carriers with low and high affinity for the substrate are identified. Nitrullin competitively inhibits the transport of³H-lysine and shows the same affinity for both carriers. It is similar to that of lysine for the low-affinity carrier and is 80-fold lower than lysine affinity for the high-affinity carrier. Kinetic characteristics of the low-affinity transport of³H-lysine and K_i of nitrullin are similar to those obtained at a reciprocal substrate-inhibitor ratio. Nitrullin does not inhibit active transport of³H-lysine into enterocytes against the background of considerable (70%) passive diffusion. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 12, pp. 648–650, December, 1996