NMR DIFFUSION-DIFFRACTION OF WATER REVEALING ALIGNMENT OF ERYTHROCYTES IN A MAGNETIC-FIELD AND THEIR DIMENSIONS AND MEMBRANE-TRANSPORT CHARACTERISTICS

''Diffusion-diffraction'' experiments on water, yielding ''q-space'' p lots, were conducted on suspensions of oxygenated (diamagnetic) human erythrocytes, (i) These suspensions displayed diffusion-diffraction of water; (ii) the shape of the q-space plots depended on the direction along which the diffusion was measured, thus implying alignment of the cells in the magnetic field of the NMR spectrometer; (iii) the diffus ion anisotropy was altered in a predictable way by converting the hemo globin to a paramagnetic form; (iv) the shapes of the q-space plots we re altered in a predictable way by inhibiting water transport; (v) the pseudo-first order rate constant characterizing the covalent inhibiti on of water transport, by p-chloromercuribenzenesulfonate (p-CMBS), wa s measured; and (vi) the cell diameter and intercellular spacing were measured from the positions of the interference minima and maxima in t he q-space plots, The relevance of these findings to NMR-based histolo gical characterization of tissues, and the implications, for magnetic resonance imaging (MRI), of erythrocyte alignment in the small vessels of the brain in particular, are noted.