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The apparent buffer value of cerebrospinal fluid in acute hypercapnia
Bulletin Europeen De Physiopathologie Respiratoire
|March 1, 1976
Summary
The cerebrospinal fluid (CSF) buffer system strengthens with increased carbon dioxide (CO2) levels during respiratory acidosis. Carbonic anhydrase activity is crucial for transporting bicarbonate ions into the CSF.
Area of Science:
- Physiology
- Neurochemistry
Background:
- Cerebrospinal fluid (CSF) plays a vital role in maintaining central nervous system homeostasis.
- Understanding the buffer mechanisms of CSF is crucial for managing respiratory acidosis.
Purpose of the Study:
- To investigate the buffer mechanism of CSF against acute hypercapnia in dogs.
- To determine the PCO2 dependency of the CSF buffer system.
- To explore the role of carbonic anhydrase in CSF bicarbonate transport.
Main Methods:
- Acute hypercapnia was induced in dogs by altering inspired CO2 concentrations (room air, 6% CO2, 12% CO2).
- CSF and arterial blood acid-base parameters were monitored dynamically.
- Experiments were repeated with carbonic anhydrase inhibited by acetazolamide.
Main Results:
- CSF acidity changes were less pronounced than in arterial blood.
- Increases in CSF bicarbonate ion concentration ([HCO3-]) were more significant.
- Apparent buffer values (delta[HCO3-]/deltapH) increased with higher CO2 levels, indicating a PCO2-dependent buffer response.
- Inhibition of carbonic anhydrase reduced the apparent buffer values of CSF.
Conclusions:
- The CSF buffer mechanism is PCO2-dependent, becoming more active as CSF PCO2 rises.
- Carbonic anhydrase likely participates in the transport of bicarbonate ions into the CSF, enhancing its buffering capacity.