Fig. 3.

Differential roles of Na,K–ATPase pumps and Kir channels for the [K⁺]_o regulation in rat hippocampus slice. (A) In control condition, 3-Hz antidromic stimulation induces a rise of [K⁺]_o in area CA3 that peaks at approximately 5.5 mM followed by a decline to approximately 4.7 mM. With addition of the sodium pump inhibitor di-hydro-ouabain (DHO), the baseline [K⁺]_o increases to approximately 5.1 mM. Antidromic stimulation (3-Hz) induces a rise of [K⁺]_o to approximately 5.9 mM but there is no [K⁺]_o recovery phase. Also absent is the undershoot of [K⁺]_o following the stimulation period. In the inset the two traces are shown superimposed, and the baseline is zeroed. (B) In control condition, 3-Hz antidromic stimulation induced a rise of [K⁺]_o that peaked at approximately 5.2 mM followed by an undershoot in [K⁺]_o. With Ba²⁺ (200 μM) in the bath, baseline [K⁺]_o increased in relation to control levels and the undershoot in [K⁺]_o following antidromic stimulation is more pronounced. In the inset the two traces are shown superimposed, and the baseline is zeroed. [From D’Ambrosio (2002), with permission.]