Abstract : A unique method for simultaneously measuring interstitial (pHe) as well as intracellular (pHi) pH in the brains of lightly anesthetized rats is described. A 4‐mm microdialysis probe was inserted acutely into the right frontal lobe in the center of the area sampled by a surface coil tuned for the collection of 31P‐NMR spectra. 2‐Deoxyglucose 6‐phosphate (2‐DG‐6‐P) was microdialyzed into the rat until a single NMR peak was detected in the phosphomonoester region of the 31P spectrum. pHe and pHi values were calculated from the chemical shift of 2‐DG‐6‐P and inorganic phosphate, respectively, relative to the phosphocreatine peak. The average in vivo pHe was 7.24 ± 0.01, whereas the average pHi was 7.05 ± 0.01 (n = 7). The average pHe value and the average CSF bicarbonate value (23.5 ± 0.1 mEq/L) were used to calculate an interstitial Pco2 of 55 mm Hg. Rats were then subjected to a 15‐min period of either hypercapnia, by addition of CO2 (2.5, 5, or 10%) to the ventilator gases, or hypocapnia (Pco2 < 30 mm Hg), by increasing the ventilation rate and volume. pHe responded inversely to arterial Pco2 and was well described (r2 = 0.91) by the Henderson‐Hassel‐balch equation, assuming a pKa for the bicarbonate buffer system of 6.1 and a solubility coefficient for CO2 of 0.031. This confirms the view that the bicarbonate buffer system is dominant in the interstitial space. pHi responded inversely and linearly to arterial Pco2. The intracellular effect was muted as compared with pHe (slope = ‐0.0025, r2 = 0.60). pHe and pHi values were also monitored during the first 12 min of ischemia produced by cardiac arrest. pHe decreases more rapidly than pHi during the first 5 min of ischemia. After 12 min of ischemia, pHe and pHi values were not significantly different (6.44 ± 0.02 and 6.44 ± 0.03, respectively). The limitations, advantages, and future uses of the combined microdialysis/31P‐NMR method for measurement of pHe and pHi are discussed.
Journal of Neurochemistry – Wiley
Published: Jan 1, 1999
Keywords: ; ; ; ; ;
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.
All for just $49/month
Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.
Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.
It’s easy to organize your research with our built-in tools.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera