Temporal association between alterations in proton extrusion and low pH adaptation
C S Owen1, M L Wahl, P M Pooler
1Department of Biochemistry and Molecular Pharmacology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Summary
Cells adapted to low extracellular pH (pHe) develop thermotolerance and elevated intracellular pH (pHi). Thermotolerance acquisition took days, while elevated pHi occurred within hours, suggesting different adaptation mechanisms.
Area of Science:
- Cell Biology
- Physiology
- Biochemistry
Background:
- Cells adapted to low extracellular pH (pHe) typically exhibit increased intracellular pH (pHi) and thermotolerance.
- The temporal relationship between these adaptive changes is not fully understood.
Purpose of the Study:
- To investigate the time course of intracellular pH (pHi) and thermotolerance development in cells adapted to low extracellular pH (pHe).
- To correlate these adaptations with cellular mechanisms like proton extrusion and pHi recovery rates.
Main Methods:
- Exposure of two cell lines to a low extracellular pH (pHe) of 6.70.
- Monitoring of intracellular pH (pHi) levels over time.
- Assessment of thermotolerance to 42 degrees C hyperthermia.
- Measurement of proton extrusion rates and pHi recovery after acidification.
Main Results:
- Elevated steady-state intracellular pH (pHi) was observed within 4 hours of exposure to low extracellular pH (pHe).
- Thermotolerance development required several days of adaptation to low extracellular pH (pHe).
- Changes in proton extrusion and the rate of pHi recovery correlated better with thermotolerance acquisition.
Conclusions:
- Intracellular pH (pHi) regulation and thermotolerance are acquired at different rates during adaptation to low extracellular pH (pHe).
- Mechanisms governing proton extrusion and pHi recovery are more closely linked to the development of thermotolerance than to the initial rise in pHi.
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