We used the fluorescent pH‐sensitive dye 2′,7′‐bis(carboxyethyl)‐5,6‐carboxyfluorescein (BCECF) to monitor intracellular pH (pHi) in single astrocytes cultured from the forebrain of neonatal rats. When exposed to a nominally CO2/HCO3− ‐free medium buffered to pH 7.40 with HEPES at 37°C, the cells had a mean pHi of 6.89. Switching to a medium buffered to pH 7.40 with 5% CO2 and 25 mM HCO3− caused the steady‐state pHi to increase by an average of 0.35, suggesting the presence of a HCO3− ‐dependent acid‐extrusion mechanism. The sustained alkalinization was sometimes preceded by a small transient acidification. In experiments in which astrocytes were exposed to nominally HCO3−‐free (HEPES‐buffered) solutions, the application and withdrawal of 20 mM extracellular NH4+ caused pHi to fall to a value substantially below the initial one. pHi spontaneously recovered from this acid load, stabilizing at a value ∼ 0.1 higher than the one prevailing before the application of NH4+. In other experiments conducted on cells bathed in HEPES‐buffered solutions, removing extracellular Na+ caused pHi to decrease rapidly by 0.5. Returning the Na+ caused pHi to increase rapidly, indicating the presence of an Na+‐dependent/HCO3−‐independent acid‐extrusion mechanism; the final pHi after returning Na+ was ∼ 0.08 higher than the initial value. This pHi recovery elicited by returning Na+ was not substantially affected by 50 μM ethylisopropylamiloride (EIPA), but was speeded up by 50 μM 4,4′‐diisothiocyanostilbene‐2,2′‐disulfonate (DIDS). Increasing (K+)− from 5 to 25 mM caused pHi to increase reversibly by ∼ 0.2 in nominally CO2/HCO3−‐free solutions, and by ∼ 0.1 in CO2/HCO3−‐containing solutions, although the initial pHi was ∼ 0.17 higher in the presence of CO2/HCO3‐. These results suggest the presence of a depolarization‐induced alkalinization. Our results suggest the presence of both HCO3− dependent and ‐independent acid‐base transport systems in cultured mammalian astrocytes, and indicate that astrocyte pHi is sensitive to changes in either membrane voltage or (K+)0 per se. © 1993 Wiley‐Liss, Inc.
Glia – Wiley
Published: Jan 1, 1993
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, 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