CSF HCO3- regulation in isosmotic conditions: The role of brain PCO2 and plasma HCO3-

E. E. Nattie, Lewis Romer

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


We have studied in anesthetized cats the response of CSF HCO3- to (1) an increase in CSF PCO2, plasma HCO3- controlled at the normal value; (2) an increase in plasma HCO3-, CSF PCO2 controlled at the normal value; and (3) an increase in both CSF PCO2 and plasma HCO3-. Plasma HCO3- was controlled via HCO3-/Cl- exchange without altering plasma Na concentration or osmolarity using the technique of peritoneal dialysis. The results suggest that CSF HCO3- regulation in these conditions is dependent on (1) a PCO2-dependent process in which HCO3- ions are formed in brain cells or choroid plexus and (2) an ionic movement of HCO3- from plasma to CSF dependent on an increase in plasma HCO3-. The first process is largely completed by 3 hours; the second takes 6 hours or more. An analysis of plasma and CSF HCO3-, Cl- and unmeasured anions (UA), (Na+ + K+ -Cl- -HCO3-), suggests that CSF HCO3- regulation may be complex involving ionic exchanges of three or more anions between brain extracellular fluid, plasma and brain cells.

Original languageEnglish (US)
Pages (from-to)177-198
Number of pages22
JournalRespiration Physiology
Issue number2
StatePublished - May 1978
Externally publishedYes


  • Brain metabolism
  • Cerebrospinal fluid
  • Extracellular fluid
  • Ionic movements

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine


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