Early and delayed changes in potassium transport during the initiation of cell proliferation in CHO culture.
Stimulation by serum of cell proliferation in G1-arrested culture of Chinese hamster ovary cells CHO-K1 was accompanied by an early (during the first minutes) and delayed (2-10 h) activation of Na+,K+-ATPase and an increase in cell K+ content from 0.5-0.6 to 0.7-0.8 mmol per gram protein. Isoproterenol acted synergistically with serum in eliciting both early and delayed changes in K+ transport and in stimulating G1----S transition. Isoproterenol alone (without serum) induced a transient increase in K+ influx via Na+,K+-ATPase without changing the cell K+ content or having any mitogenic effect. Theophylline enhanced the serum-induced early activation of Na+,K+-ATPase but inhibited both the delayed increase in cell K+ and the G1----S transition. Early serum-induced increase in K+ transport was not affected by cycloheximide, whereas net accumulation of cell K+ was abolished by the drug. It is concluded that the early and the delayed activation of Na+,K+-ATPase induced by mitogens can be dissociated; the early ionic response is related to the primary transduction of membrane signal, whereas the delayed modulation of ion transport via Na+,K+-ATPase has another function and is associated with cell growth.
Marakhova
I I
II
Institute of Cytology, Academy of Sciences of the USSR, Leningrad.
Vinogradova
T A
TA
Yefimova
E V
EV
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D001769:Blood; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D007399:Interphase; D007545:Isoproterenol / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology; D013997:Time Factors
D008934:Mitogens; D004247:DNA; D003513:Cycloheximide; D012964:Sodium; D013806:Theophylline; D000254:Sodium-Potassium-Exchanging ATPase; D007545:Isoproterenol; D012413:Rubidium; D011188:Potassium