Control of ventilation in the hypercapnic skate Raja ocellata: II. Cerebrospinal fluid and intracellular pH in the brain and other tissues

C. M. Wood, J. D. Turner, R. S. Munger, M. S. Graham

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


This study examined the possible role(s) of central-base stimuli in the increase in ventilation induced by hypercapnia in the skate, a response that is not due to an O2 signal (Graham et al., Respir. Physiol., 1990, 80: 251-270). Skate were sampled for cerebrospinal fluid (CSF) acid-base status, intracellular pH of the brain (14C-DMO method), and pHi in other tissues throughout 24 h of exposure to PiCO2 = 7.5 Torr. CSF PCO2 rapidly equilibrated with the elevated PaCO2. Despite the much lower non-HCO3-1 buffer capacity in the CSF, CSF pH was not depressed to the same extent as blood pHa. CSF pH was also regulated more rapidly, returning to control levels by 8-10 h, whereas pHa remained significantly depressed at 24 h. Similarly, the pHis of the weakly buffered brain and heart ventricle were initially compensated more rapidly than those of more strongly buffered white muscle and red blood cells. However, brain pHi adjustment slowed markedly after 4 h and stabilized at only 70% compensation by 20-24 h, suggesting that brain intracellular acidosis may play a role in the long-term increase in ventilation. CSF and brain were the only compartments which did not exhibit an apparent compounding metabolic acidosis during the initial stages of hypercapnic exposure. While these results illustrate the primacy of central acid-base regulation, they do not support a role for CSF pH in the long-term elevation of ventilation in response to hypercapnia. Depressions in pHa and brain phi appear the two mosly likely candidates for proximate stimuli.

Original languageEnglish (US)
Pages (from-to)279-297
Number of pages19
JournalRespiration Physiology
Issue number2-3
StatePublished - 1990


  • Animal, sake
  • Buffering, skate tissue
  • Cerebrospinal fluid, acid-base balance
  • Control of breathing, cerebrospinal fluid of skate, response to CO
  • Hypercapnia, ventilatory response to skate
  • pH, cerebrospinal fluid of skate
  • pH, intracellular
  • Technique in respiratory physiology, DMO
  • Ventilation, sensitivity to CO in skate

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine


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