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Brain tissue pH and ventilatory acclimatization to high altitude
S V Goldberg1, R B Schoene, D Haynor
1University of Washington, Seattle 98195.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|January 1, 1992
Summary
High altitude exposure did not cause brain acidosis, but returning to sea level did. This suggests brain pH changes may follow altered ventilation, not drive acclimatization.
Area of Science:
- Physiology
- Neuroscience
- High-altitude research
Background:
- Ventilatory acclimatization to high altitude is a complex process.
- The role of brain intracellular pH in this adaptation is not fully understood.
Purpose of the Study:
- To investigate if brain intracellular acidosis develops during high-altitude acclimatization.
- To determine if brain acidosis contributes to increased ventilation.
Main Methods:
- 31P nuclear magnetic resonance spectroscopy (31P-NMRS) was used to measure brain intracellular pH in human subjects.
- Subjects were exposed to hypobaric conditions (447 Torr) for 7 days.
- Arterial blood gases were measured to confirm ventilation changes.
Main Results:
- Brain intracellular pH remained unchanged during 7 days of hypobaric exposure.
- Upon return to sea level, brain intracellular pH significantly decreased.
- The ventilatory response to hypoxia increased after high-altitude exposure.
Conclusions:
- Brain intracellular acidosis is unlikely to be a primary stimulus for ventilatory acclimatization.
- Brain intracellular acidosis develops upon return to normoxia after chronic hypoxia.
- Brain pH may reflect changes in blood and cerebrospinal fluid pH due to altered ventilation.