Effect of CO2 on intracellular pH and contraction of retinal capillary pericytes

Qian Chen, Douglas K. Anderson

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


Purpose. To test the potential participation of pericytes in the regulation of capillary blood flow according to metabolic needs. Methods. The authors measured the change in extracellular pH (pH(o)), intracellular pH (pH(i)), and contractile tone of cultured bovine retinal pericytes when the ambient carbon dioxide (CO2) level was changed. Results. Raising the partial pressure of CO2 (PCO2) from 5% to 10% or 20% acidified the medium, decreased the pH(i), and relaxed the pericytes. Lowering the PCO2 from 5% to 0% or 2% alkalized the medium, raised the pH(i), and contracted the pericytes. The reactions of pericytes in both cases were dose dependent. When the pH(o) was kept at ~7.4 as the PCO2 was changed by adjusting the ratio of NaHCO3 and NaCl in the medium (or by using HEPES buffer when PCO2 was zero), both elevating and lowering the PCO2 caused intracellular acidification but did not change the contractile tone of the retinal pericytes significantly. Conclusions. The effect of CO2 on the pH(i) and the contractility of pericytes is mediated primarily by its influence on the pH(o). Elevation of CO2 causes pericytes to relax, whereas dispersion of CO2 causes pericytes to contract under the condition that allows pH(o) to be affected by PCO2. Therefore, pericytes may contribute to the regulation of local blood flow by their response to the change in local metabolic conditions.

Original languageEnglish (US)
Pages (from-to)643-651
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Issue number3
StatePublished - 1997


  • carbon dioxide
  • contraction
  • extracellular pH
  • intracellular pH
  • metabolic autoregulation of blood flow
  • pericyte
  • retinal capillaries

ASJC Scopus subject areas

  • Ophthalmology


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