Intracellular Na+ activity in cultured mouse oligodendrocytes

✍ Scribed by K. Ballanyi; H. Kettenamann

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 510 KB
• Volume: 26
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.490260408

✦ Synopsis

Abstract

Na^+^‐selective double‐barrelled microelectrodes were used to measure the intracellular Na^+^ activity (a^i^~Na~) and membrane potential (E~m~) in oligodendrocytes from cultures of embryonic mouse spinal cord. In Na^+^‐free solutions a^i^~Na~ rapidly fell from its baseline of about 15 mM to values below 1 mM. Elevation of the K^+^ concentration in the bath ([K^+^]~o~) from 5.4 to 15 or 50 mM elicited an a^i^~Na~ decrease of 4.7 or 9.0 mM, respectively. Ouabain blocked the a^i^~Na~ decrease in response to 50 mM K^+^ by 37%. Bath application of 1 mM glutamate resulted in a membrane depolarization of 4.5 mV and a concomitant rise of a^i^~Na~ by 8.6 mM. a^i^~Na~ increased by approximately 11 mM after washout of a solution containing 20 mM NH~4~^+^. This a^i^~Na~ increase was not blocked by amiloride, excluding a major contribution of a Na^+^/H^+^ antiporter. We conclude that, in cultured oligodendrocytes, transmembraneous Na^+^ movements are involved in pH regulation, glutamate causes an influx of Na^+^, and that the Na^+^/K^+^ pump and passive KCI uptake contribute to K^+^ accumulation.