Elevated extracellular potassium concentration in unstimulated spinal dorsal horns of frogs.
The extracellular K+ concentration, [K+]e, was studied in unstimulated spinal cords in situ or in isolated spinal cords of frogs. The [K+]e in the dorsal horn at a depth of 150-500 microM exceeded the [K+]e found in the submeningeal fluid, in most of the upper dorsal horn and in the ventral horn by as much as 2.0 mmol . 1(-1). A substantially higher [K+]e, by 0.5-1.0 mmol . 1(-1) was also found in the intermediate region. The blockade of synaptic activity and of spontaneous activity in isolated spinal cords superfused by Ringer solution with high Mg2+ or Mn2+ concentrations decreased [K+]e in the dorsal horn and intermediate region to about 3.0 mmol . 1(-1). Similarly, the increase of spontaneous activity evoked in the isolated cords by changing the temperature of the Ringer solution, was associated with an increase of [K+]e in the dorsal spinal horn. The data suggest that the high [K+]e in the unstimulated dorsal horn results from K+ accumulation during spontaneous activity of interneurones, and its possible physiological role is discussed.
D000818:Animals; D005110:Extracellular Space / Q000378:metabolism*; D005727:Ganglia, Spinal / Q000378:metabolism*; D007395:Interneurons / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D011896:Rana temporaria; D009435:Synaptic Transmission
D007473:Ion Channels; D011188:Potassium