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Changes in acidity of mouse tumor by hyperthermia
Summary
Hyperthermia treatment increases acidity in mouse tumors, not muscle tissue. This heat-induced acidity in tumors may enhance sensitivity to further heating and inhibit thermal damage repair.
Area of Science:
- Oncology
- Biophysics
- Physiology
Background:
- Intratumor pH is typically acidic and heterogeneous.
- Understanding pH changes during hyperthermia is crucial for cancer treatment efficacy.
Purpose of the Study:
- To investigate the effects of hyperthermia on intratumor and intramuscle pH in mice.
- To determine the duration and potential causes of heat-induced pH changes in tumors.
Main Methods:
- Utilized bulb-type pH microelectrodes to measure intratissue pH in SCK tumors and leg muscle of unanesthetized mice.
- Measurements were taken before, during, and after hyperthermia (43.5°C for 30 minutes).
Main Results:
- Intratumor pH (average 6.96) was more acidic than intramuscle pH (average 7.46).
- Hyperthermia induced a significant increase in tumor acidity (pH decrease of ~0.2 units), but not in muscle.
- This increased tumor acidity persisted for 12 hours post-heating before gradually recovering.
Conclusions:
- Hyperthermia exacerbates tumor acidity, potentially by increasing acidic metabolites and impairing drainage due to vascular damage.
- The resulting increase in tumor acidity may play a role in inhibiting thermal damage repair and sensitizing tumor cells to subsequent hyperthermia treatments.