Water permeability changes studied by ¹⁷O nuclear magnetic resonance during differentiation of Friend leukemia cells

Water permeability of Friend leukemia cells was studied by ¹⁷O nuclear magnetic resonance during differentiation induced by dimethyl sulfoxide (Me₂SO). While in noninduced cells water permeability was essentially constant during the growth period, in the Me₂SO-induced cells there were two distinct periods at which the water permeability was increased by at least an order of magnitude. These periods correspond to approximately one doubling time and 6 days of growth. This change in water permeability is not due to direct interaction of Me₂SO with the membrane but must be ascribed to structural changes in the membrane during the course of differentiation.