Nuclear magnetic resonance investigation of human erythrocytes in the presence of manganese ions. Evidence for a thermal transition

Abstract

Water proton transverse relaxation was investigated in whole blood and washed erythrocytes samples, respectively, at various temperatures and manganese concentrations. Water diffusional exchange controls proton relaxation in whole blood samples at higher Mn 2+ concentrations (20–30 mM) or in washed erythrocyte samples at low Mn 2+ content (1–5 mM). Mn 2+ uptake is significant in washed normal erythrocyte samples when its concentrations is about 18 mM or higher in the medium, at temperatures below about 26°C. The thermal transition as revealed by the NMR doping method represents a switch from a water exchange process, mainly seen in the higher temperature range, to a paramagnetic ion controlled water proton relaxation in the lower temperature range.