title: The uptake of manganese ions and the apparent thermal transition of the erythrocyte membranes.
abstract: The nuclear magnetic resonance manganese doping technique is currently used for the determination of the water diffusional exchange time through human erythrocyte membranes. An apparent thermal transition at 26 degrees C was noticed at 18-30 mM manganese doping in the suspending solution. An analysis in terms of a two-phase nuclear spin exchanging system revealed that apparent thermal transitions are expected to occur in the upper and lower temperature regions. They represent a shift from intermediate exchange rates where water diffusion through the membrane is dominant to either fast or slow exchange rates where proton relaxation is the controlling process. The lower temperature apparent transition may be altered by the intracellular manganese concentration; the lower the Mn2+ concentration the lower the transition. Also according to this interpretation only a fraction of the erythrocytes are significantly permeated by Mn2+. The upper transition depends on the Mn2+ concentration in the extracellular volume; it decreases with decreasing Mn2+ concentration.
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004910:Erythrocyte Membrane / Q000502:physiology*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008345:Manganese / Q000097:blood*; D011485:Protein Binding; D013696:Temperature; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D008345:Manganese