Dynamic effects of Hg2+-induced changes in cell volume.
Using a microfluidic volume sensor, we studied the dynamic effects of Hg2+ on hypotonic stress-induced volume changes in CHO cells. A hypotonic challenge to control cells caused them to swell but did not evoke a significant regulatory volume decrease (RVD). Treatment with 100 muM HgCl2 caused a substantial increase in the steady-state volume following osmotic stress. Continuous hypotonic challenge following a single 10-min exposure to HgCl2 produced a biphasic volume increase with a steady-state volume 100% larger than control cells. Repeated hypotonic challenges to cells exposed once to Hg2+ resulted in a sequential approach to the same steady-state volume. Stimulation after reaching steady state caused a reduction in peak cell volume. Repeated stimulation was different than continuous stimulation resulting in a more rapid approach to steady state. Substituting extracellular Na+ with impermeant NMDG+ in the hypotonic solution produced a rapid RVD-like volume decrease and eliminated the Hg2+-induced excess swelling. The volume decrease in the presence of Hg2+ was inhibited by tetraethylammonium and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium, blockers of K+ and Cl(-) channels, respectively, suggesting that part of the Hg2+ effect was increasing NaCl influx over KCl efflux. The presence of multiple phases of steady-state volume and their sensitivity to the stimulation history suggests that factors beyond solute fluxes, such as modification of mechanical stress within the cytoskeleton also plays a role in the response to hypotonic stress.
Heo
Jinseok
J
Department of Mechanical and Aerospace Engineering, SUNY-Buffalo, 340 Jarvis Hall, Buffalo, NY 14260, USA.
Meng
Fanjie
F
Sachs
Frederick
F
Hua
Susan Z
SZ
D000818:Animals; D016466:CHO Cells; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D048429:Cell Size / Q000187:drug effects*; D006224:Cricetinae; D003412:Cricetulus; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D007038:Hypotonic Solutions / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D008627:Mercuric Chloride / Q000494:pharmacology*; D046210:Microfluidic Analytical Techniques; D012964:Sodium / Q000378:metabolism; D013997:Time Factors
D007038:Hypotonic Solutions; D008627:Mercuric Chloride; D012964:Sodium