Document Detail

Thermotolerance and intracellular pH in two Chinese hamster cell lines adapted to growth at low pH.
MedLine Citation:
PMID:  8592004     Owner:  NLM     Status:  MEDLINE    
As an in vitro model for the low extracellular pH (pHe) which has frequently been observed in tumors, cell lines have been grown in a low-pH medium in order to allow cell adaptation to that milieu. Two Chinese hamster cell lines [Chinese hamster ovary (CHO) and Chinese hamster ovarian carcinoma (OvCa)] were compared, both of which acquired thermotolerance during 42 degrees C heating in pHe = 7.3 buffer, but not in pHe = 6.7 medium unless grown at that pH long enough to become adapted. CHO cells, even when acutely acidified, showed higher intracellular pH (pHi) values in a suspension assay than OvCa cells, which confirmed the danger of comparing absolute values of pHi between cell lines. Despite this fundamental difference, relative changes in pHi were similar in that both lines showed a higher pHi in adapted than in unadapted cells, over the range of pHe values tested. The upregulation of pHi was statistically significant, but the two lines differed in the time frame over which adaptation occurred. OvCa cells acquired an enhanced ability to develop tolerance to 42 degrees heat at pHe = 6.7 in 4 days, but the CHO cells acquired this ability more progressively, achieving a maximum ability at approximately 100 days. In contrast, both lines were able to upregulate their pHi within 4 hours of being exposed to pH 6.7 medium. A further indication of different biochemical mechanisms at work was the opposite effects seen on pHi in the two cell lines upon the removal of extracellular CO2/HCO3-. The differential between adapted and unadapted OvCa cells was enhanced by removal of bicarbonate, whereas CHO cells seemed less stable and the data with greater scatter failed to show any difference between adapted and unadapted cells.
M L Wahl; R A Coss; S B Bobyock; D B Leeper; C S Owen
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of cellular physiology     Volume:  166     ISSN:  0021-9541     ISO Abbreviation:  J. Cell. Physiol.     Publication Date:  1996 Feb 
Date Detail:
Created Date:  1996-04-01     Completed Date:  1996-04-01     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0050222     Medline TA:  J Cell Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  438-45     Citation Subset:  IM    
Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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MeSH Terms
Adaptation, Physiological*
Bicarbonates / pharmacology
CHO Cells
Cell Division / physiology*
Cell Survival
Extracellular Space / metabolism
Hot Temperature*
Hydrogen / metabolism*
Hydrogen-Ion Concentration
Intracellular Membranes / metabolism*
Time Factors
Tumor Cells, Cultured
Grant Support
Reg. No./Substance:
0/Bicarbonates; 1333-74-0/Hydrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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