This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cook, J. A. Articles by Fox, M. H. Search for Related Content PubMed PubMed Citation Articles by Cook, J. A. Articles by Fox, M. H.

Effects of Chronic pH 6.6 on Growth, Intracellular pH, and Response to 42.0°C Hyperthermia of Chinese Hamster Ovary Cells¹

Department of Radiology and Radiation Biology, Colorado State University, Fort Collins, Colorado 80523

Culturing Chinese hamster ovary cells in low pH (6.6) medium for several months altered the reproductive survival of these cells to combined low pH treatments and 42.0°C heating. We isolated new pH-resistant cells (identified as pHV-2) with enhanced ability to grow and divide under a low pH (6.6) environment. Their growth characteristics include (a) a plating efficiency of 70%, (b) a doubling time of 16 to 17 h, and (c) a steady state intracellular pH 0.12 pH units higher than for cells grown at a normal pH of 7.3. The pHV-2 cells had 100- to 200-fold increases in survival after 5 h of heating compared to cells incubated at low pH (6.6) for 4 h prior to and during the heat treatments. In addition, they developed a significant degree of thermotolerance. We measured a progressive decline in the intracellular pH as a function of time at 42.0°C. However, the decrease in the intracellular pH did not seem to be correlated with the increased heat sensitivity. The ability to select for low pH variants may have important implications in the extrapolation of in vitro hyperthermic data to the in vivo situation.

¹ Supported by United States Public Health Service Grant CA25636, awarded by the National Cancer Institute, Department of Health and Human Services, and the United States Department of Agriculture Animal Health and Disease Program. Reported in part at the 32nd Radiation Research Meeting, March 25–29, 1984, Orlando, FL, and the 35th Radiation Research Meeting, Feb. 21–26, 1987, Atlanta, GA.

² This work is submitted by this author in partial fulfillment for the degree of Doctor of Philosophy. Present address: National Cancer Institute, Bldg. 10, Rm B3B69, Bethesda, MD 20892.

³ To whom correspondence should be addressed.

Received 6/15/87. Revised 12/21/87. Accepted 2/ 1/88.

This article has been cited by other articles:

				R. A. Coss, C. W. Storck, C. Daskalakis, D. Berd, and M. L. Wahl Intracellular Acidification Abrogates the Heat Shock Response and Compromises Survival of Human Melanoma Cells Mol. Cancer Ther., April 1, 2003; 2(4): 383 - 388. [Abstract] [Full Text] [PDF]