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. 2005 Apr 6;25(14):3601–3612. doi: 10.1523/JNEUROSCI.4290-04.2005

Figure 7.

Figure 7.

Experimental manipulations of Cl- flux. A, Blockade of the Cl- cotransporter with bumetanide. Top, Interepisode intervals before, during (50 μm AP-5 plus 20 μm CNQX) plus 10 μm bumetanide, and during washout of bumetanide. Bumetanide (bumet) completely suppressed activity, which recovered after an initial blockade (3 experiments, in the presence of AP-5 and CNQX, E10-E11 embryos). Bottom, Left, Whole-cell current response of spinal neuron to short (20 s) pressure applications of different GABA concentrations (10, 50, and 100 μm; marked by short lines) in the absence or presence of bath-applied bumetanide (10 μm; marked by dotted lines). Bumetanide does not block the GABAergic current. Currents were recorded from the same cell at a holding potential of -40 mV. Current-voltage relationship for 50 μm GABA application, under control conditions, and in the presence of 10 μm bumetanide (shown on right). Bumetanide has no effect on the reversal potential for GABA but has a slight effect on the conductance. GABA and bumetanide were applied as in the left panel experiments, but a voltage-ramp protocol was used for measurement of the current-voltage relationship. B, Manipulations of [Cl-]ext. Top, Ventral root recordings for three different values of [Cl-]ext. Decreasing the [Cl-]ext has minimal effect on episode duration but strongly increases interepisode interval. Bottom, Plot of the interepisode intervals under three different [Cl-]ext (as in the top panel in B; 3 experiments). Numbers on graph are mean ± SE, which at p = 0.05 were significantly different (ANOVA test). The changes in extracellular chloride were made in the presence of glutamatergic antagonists (for additional details, see Materials and Methods).