AJP - Cell Physiology, Vol 242, Issue 3 184-C191, Copyright © 1982 by American Physiological Society
Bath osmolality: effect on water permeability of epithelial tissue
Y. T. Lau, R. H. Parsons, G. A. Feeney and K. L. Walker
When hyperosmotic gradients from 100 to 500 mosM are used to produce a
water flux, the water permeability of live and potassium cyanide
(KCN)-poisoned frog skin decreases with increasing osmotic gradients. In
addition, as the total bath osmolality (corium + epithelial) increases
there is a reduction in tissue water. Examination of the tissue cellular
and extracellular compartments shows that cell shrinkage caused by the
increasing hyperosmolality of the bathing medium correlates with the
decrease in osmotic permeability. When the bath osmolality is held constant
and cell volume decreases, there is a decrease in the water permeability.
High potassium in the external bathing medium causes cell swelling that is
associated with an increase in water permeability. These data support the
hypothesis that a number of conditions known to affect the water
permeability of frog skin do so partly or wholly as a result of a change in
the cell volume, which either directly or indirectly alters the osmotic
permeability of a rate limiting barrier, possibly the cell membrane.
