Adaptation of mouse leukemic cells (L5178Y) to anisotonic media: II. Cell growth

Abstract

In hypotonic media, with o smolarity as low as 185 mosM, mouse leukemic cells (L5178Y) are able to grow indefinitely but at a reduced rate compared with cells in normal medium. The change in growth rate is immediate, readily reversible, and dependent upon the initial cell concentration in the culture. At osmolarities below 185 mosM cells may undergo a few divisions, but some loss of viability is evident even if the cells are returned to normal medium after a short exposure. Failure of growth below 185 mosM is due to the reduction in osmotic pressure rather than the NaCl concentration of the medium, because the cells can grow at salt concentrations lower than 124 mosM if the osmotic pressure is maintained with sucrose. The factor that limits growth is probably the reduction in cellular K + associated with adaptation to media of reduced osmolarity. Growth is also inhibited when the osmolarity is raised above 400 mosM. Manipulation of the external K + concentration cannot extend the range of osmolarities that can support growth, although the rate of growth can be influenced.