Cell volume regulation in ehrlich ascites tumor cells

Abstract

Abstract Ehrlich cells subjected to anisoosmolar media show very rapid volume changes. In hypertonic media they shrink. In hypotonic media they swell but the rapid initial swelling is followed by a regulatory shrinkage lasting ca. 30 minutes. Cells suspended in media with identical ionic concentrations but different total osmolarity (adjusted by sucrose) were compared. These studies revealed that swollen cells adjust their volume by decreasing the amount of intracellular K + and ninhydrin positive substances. Intracellular Na + and ATP concentrations were unchanged. Accordingly 42 K + flux analysis showed that the (passive) cell membrane permeability for K + is increased to a minor degree and the Na + permeability unaffected. The increased K + permeability could not be correlated to an increase in 45 Ca 2+ influx.