Fig. 5. NKCC1 renders GABA excitatory in the Lymnaea CNS. (A) Addition of the NKCC1 antagonist bumetanide (100 µmol l^-1) to the perfusate significantly decreases action potential (AP) firing frequency (grey bars; N=6, P=0.01 paired t-test). The normoxic decrease in AP frequency caused by bumetanide is not significantly different from the decrease observed in the normoxia to hypoxia switch (black bars vs grey bars; P=0.844 unpaired t-test). (B) Spontaneous firing of APs was prevented by the addition of 100 µmol l^-1 bumetanide (at bar).