Adaptive enhancement of amino acid transport in human leukemia leukocytes: studies with alpha-aminoisobutyric acid.

摘要: Initial rates of accumulation (Vi) [3-14C] alpha-aminoisobutyric acid (AIB) by human leukemic leukocytes increased markedly and progressively during 240 minute incubations in amino acid-deficient media. Absolute increments were greater blast cells from patients with acute lymphoblastic leukemia myeloblastic than lymphocytes chronic lymphocytic leukemia, but per cent did not differ. Time-related increases appear to be restricted an active mechanism for AIB entry could attributed cell damage, concomitant alterations the incubation media, or progressive reduction transinhibition entry. Studies two populations revealed these associated augmented Vmax a apparent Km, suggesting enhanced capacity affinity transport system AIB. failed develop (CLL) lymphocyte partially reduced continuous exposure high extracellular concentrations. Hence, this phenomenon may represent adaptive response environmental deprivation. Adaptation involve de novo protein RNA synthesis, since it was seen which treated cycloheximide actinomycin D. However, unlike previous observations nonmalignant cells, once triggered, completely suppressed underwent large degree adaptation.