Water proton spin-lattice relaxation behaviour in heterogeneous biological systems

The water proton spin-lattice relaxation rate has been measured for a condensed 50% deuterated erythrocyte water system. Nuclear relaxation data, obtained in non-selective and selective modes, indicate that cross relaxation between erythrocyte and water protons occurs. The observed selective relaxation enhancement is interpreted in terms of intermolecular nuclear interactions modulated by motions which satisfy the ω_oT_c > 1 condition. Selective relaxation rates are here proposed to be more sensitive to interface characteristics than the non-selective ones.