In vivo measurement of regional brain and tumor pH using [14C]dimethyloxazolidinedione and quantitative autoradiography. II: Characterization of the extracellular fluid compartment using pH-sensitive microelectrodes and [14C]sucrose.

Abstract

We measured the extracellular (interstitial) pH (pHe) of RG-2 rat gliomas using H+-sensitive microelectrodes and estimated the volume of tumor extracellular space based on the tissue-plasma ratio of [14C]sucrose. The average RG-2 pHe was 7.63 +/- 0.15 (mean +/- SD, n = 6), whereas the average pHe of contralateral brain tissue was 7.34 +/- 0.10 (n = 3) and arterial pH was 7.36 +/- 0.02. RG-2 extracellular space water volume was estimated to be 0.3 ml water/g tissue. In separate experiments in normal, nontumored rats, intracellular pH (pHi) was calculated for nine gray and white matter regions based on measurements of tissue and plasma [14C]dimethyloxazolidinedione concentration. pHi values ranged from 6.80 to 6.94, and no consistent gray-white differences were observed. Our data suggest that tumor pHi is not more acidic than that of normal brain tissue and that the observed alkalinity of primary brain tumors is due to the presence of a large alkaline extracellular space.

• Authors: J B Arnold, R P Kraig, D A Rottenberg
• Journal: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism (J Cereb Blood Flow Metab) Vol. 6 Issue 4 Pg. 435-40 (Aug 1986) ISSN: 0271-678X [Print] United States
• PMID: 3733903 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Sucrose
• Dimethadione

Topics

• Animals
• Autoradiography (methods)
• Brain (physiopathology)
• Brain Neoplasms (physiopathology)
• Dimethadione (analysis)
• Extracellular Space (physiology)
• Glioma (physiopathology)
• Hydrogen-Ion Concentration
• Male
• Microelectrodes
• Rats
• Rats, Inbred F344
• Sucrose (analysis)