Intracellular pH shifts capable of uncoupling cultured oligodendrocytes are seen only in low HCO3− solution

✍ Scribed by H. Kettenmann; B. R. Ransom; W.-R. Schlue

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 965 KB
• Volume: 3
• Category: Article
• ISSN: 0894-1491
• DOI: 10.1002/glia.440030204

✦ Synopsis

Electrical coupling between cultured mouse oligodendrocytes was transiently blocked when pHi was decreased below about 6.5 using the NH,+ prepulse method. This uncoupling could, however, only be achieved if the dominant pH, regulating mechanism in these cells, the Na+/HC03-cotransporter, was blocked by lowering bath [HC03-]. Under this condition, an NH4+ prepulse caused pHi to decrease toward the passive distribution for H+ (i.e., about pH 6.2). In the presence of normal bath [HCO3-1 an NH4+ prepulse did not decrease pHi below 6.5 even when the second pHi regulating mechanism, the Na'/H+ exchanger, was blocked by amiloride, and consequently oligodendrocytes could not be uncoupled. Increasing C02, which uncouples glial cells in situ (Connors et al: J . Neurosci. 4:1324-1330, 1984), did not uncouple cultured 'digodendrocytes in the presence of normal bath [HC03-l, but did cause uncoupling in low IHC03-I solution. These results indicate that electrical coupling between cultured oligodendrocytes is sensitive to pHi; in normal bath [HCO,-], however, the pH, regulation of these cells is so effective that standard techniques for intracellular acidification 2.re unable to lower pH, to levels which cause the closure of oligodendrocyte gap junctions.