title: Permeation of a spin-label phosphate into the human erythrocyte.
abstract: The reduction of spin-labels by human erythrocytes can be used to follow their penetration into these cells. The neutral spin-label alcohol Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl) diffuses through the membrane very quickly. The membrane is virtually impermeable to the positively charged spin-label Tempo-choline (N,N-dimethyl-N-(2',2',6',6'-tetramethyl-4'-piperidinyl-1-oxyl)-2-hydroxyethylammonium chloride). The negatively charged spin-label Tempo phosphate (4-phospho-2,2,6,6-tetramethylpiperidinyl-l-oxyl) is reduced at 37 degrees, with a half-time of about 1 hr. The reduction occurs internally following the rate-limiting transport of the label across the erythrocyte membrane. Reduction of this spin-label is greatly diminished by the specific inhibitor of anion transport, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS). The rate of transport depends strongly on the transmembrane electrical potential.
mesh_terms: D000328:Adult; D001692:Biological Transport; D002463:Cell Membrane Permeability; D003497:Cyclic N-Oxides / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D004912:Erythrocytes / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D008564:Membrane Potentials; D010084:Oxidation-Reduction; D010710:Phosphates / Q000378:metabolism*; D010880:Piperidines / Q000378:metabolism*; D013113:Spin Labels; D013696:Temperature; D013997:Time Factors
chemical_list: D003497:Cyclic N-Oxides; D010710:Phosphates; D010880:Piperidines; D013113:Spin Labels; C001803:tempol