Figure 6.
Time course of a typical experiment illustrating the volume response to Mg2+ elevation. (a) Vertical lines indicate: change of external solution from PS to ILS (1); plasma membrane permeabilization with digitonin; the thick horizontal bar denotes the duration of detergent treatment (2); increased external Mg2+ from 5 to 70 mM by isoosmotic replacement of K+ (3); and return to 5 mM Mg2+ (4). (b) Summary of volume responses to different Mg2+ levels. Data are mean ± SE of 4–50 independent experiments for each condition. Inset shows experimentally observed relative volume changes (normalized to volume observed with 5 mM Mg2+, (●) induced by different external Mg2+ (indicated in mM) and compared to those expected due to reduction of counterion concentration (expressed as relative concentration change) and lower intragel osmotic pressure (○).