Regulatory changes in the K+, Cl- and water contents of HeLa cells incubated in an isosmotic high K(+)-medium.
HeLa cells had their normal medium replaced by an isosmotic medium containing 80 mM K+, 70 mM Na+ and 100 microM ouabain. The cellular contents of K+ first increased and then decreased to the original values, that is, the cells showed a regulatory decrease (RVD) in size. The initial increase was not inhibited by various agents except by substitution of medium Cl- with gluconate. In contrast, the regulatory decrease was inhibited strongly by addition of either 1 mM quinine, 10 microM BAPTA-AM without medium Ca2+, or 0.5 mM DIDS, and partly by either 1 mM EGTA without medium Ca2+, 10 microM trifluoperazine, or substitution of medium Cl- with NO3-. Addition of DIDS to the NO3(-)-substituted medium further suppressed the K+ loss but the effect was incomplete. Intracellular Ca2+ showed a transient increase after the medium replacement. These results suggest that the initial increase in cell K+ is a phenomenon related to osmotic water movement toward Donnan equilibrium, whereas the regulatory K+ decrease is caused by K+ efflux through Ca(2+)-dependent K+ channels. The K+ decrease induced a decrease in cellular water, i.e., RVD. The K+ efflux may be more selectively associated with Cl- efflux through DIDS-sensitive channels than the efflux of other anions.
Ikehara
T
T
Department of Physiology, School of Medicine, University of Tokushima, Japan.
Takahashi
A
A
Yamaguchi
H
H
Hosokawa
K
K
Masuya
T
T
Miyamoto
H
H
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism*; D003470:Culture Media; D006367:HeLa Cells; D006801:Humans; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism* / Q000494:pharmacology; D011803:Quinine / Q000494:pharmacology; D013997:Time Factors; D014867:Water / Q000378:metabolism*
D002712:Chlorides; D003470:Culture Media; D014867:Water; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D010042:Ouabain; D011803:Quinine; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D011188:Potassium; D002118:Calcium