DETERMINATION OF CELLS WATER MEMBRANE-PERMEABILITY - UNEXPECTED HIGH OSMOTIC PERMEABILITY OF SACCHAROMYCES-CEREVISIAE

Wafer permeability. (Lp), calculated from the volume variations of cel ls subjected to an osmotic shock, is classically used to characterize cell membrane properties. In this work, we have shown the importance o f the kind of mixing reactor used to measure the Lp parameter. A mathe matical model including the mixing time constant has been proposed all owing an accurate Lp estimation even though the mixing time constant i s higher than the cell time constant obtained in response to a perfect shock. The estimated Lp values of human leukemia K562 cells were foun d to be the same whatever the mixing time constant. The Lp value of Sa ccharomyces cerevisiae could not be exactly estimated. However, S. cer evisiae has unexpectedly high water permeability, implying that this y east may contain water channels in the membrane. (C) 1997 John Wiley & Sons, Inc.