Transmembrane Water Exchange Research Articles

Regulation of transmembrane water transfer by rotational motion of plant cell protoplasm

By changing the velocity of protoplasm motion, a plant cell with a membrane permeability coefficient of 10−3 cm/s is able to control the intensity of transmembrane water exchange. The data were obtained by synchronous tracking, with the effective water self-diffusion coefficients measured by pulsed nuclear magnetic resonance.

The magnetic properties and water dynamics of the red blood cell: a study by proton-NMR lineshape analysis.

The magnetic properties and water dynamics of human red blood cells were examined by analysis of the water proton spectra of suspensions of oxygenated, deoxygenated, carbon monoxide-treated, and methemoglobin-containing cells at a magnetic field strength of 7.05 T. Total lineshape analysis of spectra from deoxygenated red blood cell suspensions was performed to determine the transmembrane water exchange rate, the contribution of diffusion in local magnetic field gradients to the transverse relaxation rate, and the difference between the intra- and extracellular chemical shifts of water protons. Mathematical models are proposed to account for the dependence of the chemical shifts and linewidths of these spectra on the magnetic susceptibility or density of the cells.

On the origin of paramagnetic inhomogeneity effects in whole blood.

Asymmetric 7 T proton NMR signals of water in RBC suspensions containing intracellular deoxyhemoglobin are composites of chemically shifted extracellular and intracellular resonances broadened by gradient diffusion and modulated by transmembrane water exchange. This allows assessment of field dependences of acute hematoma intensities in proton MRIs at lower field strengths (less than or equal to 1.5 T).