title: Uptake and release of 2-aminoisobutyrate by Leishmania donovani: culture-age dependent effects of osmolality and of protein kinase inhibitors.
abstract: The rate of uptake of 2-aminoisobutyrate (AIB), a non-metabolizable analogue of alanine, by Leishmania donovani was investigated as a function of culture age and osmolality in the presence of protein kinase inhibitors and of glucose, glutamate or proline. Hyperosmolality inhibited AIB uptake by cells of both growth stages, but to a greater extent for log than for stationary cells. Staurosporine, a protein kinase C inhibitor, had no effect on AIB uptake by cells of either culture age, but it reduced the rate of AIB release in response to hypo-osmolality, and more so in stationary cells than in log cells. Genistein, a protein-tyrosine kinase inhibitor, caused a small increase in AIB uptake by log cells under both iso- and hyperosmotic conditions, but had no effect on AIB uptake by stationary cells. Genistein also caused a small increase in the rate of release of AIB in response to a decrease in osmolality. Brief preincubation with glucose, glutamate or proline of cells that had been depleted of their osmolytes by prior exposure to hypo-osmolality caused an increase in AIB release by log cells, but a decrease by stationary cells. Similarly, whereas glucose and glutamate increased the rate of AIB uptake by log cells, and proline inhibited it, they had no effect on AIB uptake by stationary cells. Thus AIB uptake and release are sensitive to changes in osmolality, to protein kinase inhibitors, and to certain nutrients in a manner that changes markedly with culture age.
authors.affiliation: Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Blum
mesh_terms: D000409:Alanine / Q000494:pharmacology; D000621:Aminoisobutyric Acids / Q000378:metabolism / Q000493:pharmacokinetics*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D016922:Cellular Senescence / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein; D005947:Glucose / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D006982:Hypertonic Solutions; D007529:Isoflavones / Q000494:pharmacology; D007893:Leishmania donovani / Q000166:cytology / Q000378:metabolism*; D009994:Osmolar Concentration; D011392:Proline / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D019311:Staurosporine / Q000494:pharmacology
chemical_list: D000621:Aminoisobutyric Acids; D004791:Enzyme Inhibitors; D006982:Hypertonic Solutions; D007529:Isoflavones; D047428:Protein Kinase Inhibitors; C100049:2-aminoisobutyric acid; D018698:Glutamic Acid; D011392:Proline; D019833:Genistein; D019311:Staurosporine; D005947:Glucose; D000409:Alanine