title: The role of calcium in the regulation of sugar transport in the pigeon red blood cell.
abstract: The saturable, 'carrier-mediated' pathway for sugar transport in pigeon red blood cells may be stimulated by metabolic depletion or by loading the cells with Ca by means of a high-voltage discharge or the ionophore A 23187. All of these methods for stimulating the saturable pathway of sugar transport also cause a drop in cellular ATP levels. The relationship between the stimulation of transport and the fall in ATP is very similar in metabolically depleted or Ca-loaded cells, but cells treated with Ca and A23187 show a greater stimulation of transport than would be expected from the decline in ATP. Altering free Ca2+ levels during metabolic depletion has little or no effect on stimulation of the saturable pathway. Conversely, metabolic depletion of fresh cells in Ca-free solutions has no detectable effect on intracellular free Ca2+ levels. These results suggest that Ca2+ ions are not involved in regulation of this pathway. The non-saturable pathway for sugar transport is stimulated by a rise in cell Ca. This process is probably stimulated half-maximally by about 10 microM-free Ca2+.
mesh_terms: D019325:3-O-Methylglucose; D000255:Adenosine Triphosphate / Q000097:blood; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000097:blood / Q000494:pharmacology*; D010856:Columbidae / Q000097:blood*; D003571:Cytochalasin B / Q000494:pharmacology; D004058:Diffusion; D004912:Erythrocytes / Q000378:metabolism*; D066298:In Vitro Techniques; D008757:Methylglucosides / Q000097:blood*; D008759:Methylglycosides / Q000097:blood*; D012430:Ruthenium Red / Q000494:pharmacology; D013997:Time Factors; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D008757:Methylglucosides; D008759:Methylglycosides; D014475:Uncoupling Agents; D012430:Ruthenium Red; D019325:3-O-Methylglucose; D003571:Cytochalasin B; D000255:Adenosine Triphosphate; D002118:Calcium