AJP - Cell Physiology, Vol 236, Issue 5 238-C243, Copyright © 1979 by American Physiological Society
Effect of ammonium chloride on osmotic behavior of red cells in nonelectrolytes
M. D. Sass
Ammonium chloride, demonstrated to be a permeating electrolyte for human
red cells in water or sodium chloride solutions, has been shown to act as
if it contributes osmotic support in the presence of sucrose. The
additional protection provided by ammonium chloride against hemolysis in
hypotonic sucrose was found to approximate the milliosmolar concentration
of the added salt. In view of previous suggestions that potassium loss was
responsible for the increased protection observed with hypotonic
nonelectrolyte alone, it was considered reasonable that the further
protection afforded by ammonium chloride might reflect a comparable
mechanism. Such a relationship was not observed. When added to isosmotic
sucrose, ammonium chloride was found to be as effective as sodium chloride
in preventing rather than augmenting potassium loss, in accord with the
observations of others. Under hypotonic conditions, however, the addition
of ammonium chloride had no effect on potassium loss beyond that observed
in hypotonic sucrose alone. Equivalent additions of sodium chloride
eliminated the potassium loss entirely. It was concluded that sucrose, and
possibly other nonelectrolytes, acted to modify the red cell's permeability
to ammonium chloride. It is this conversion of ammonium chloride to an
impermeant molecule that is considered to be responsible for the observed
osmotic support as well as for the markedly disparate findings in sodium
chloride solutions.
