Figure 7. GIRK-channel dependent inhibition of release by GABA_B receptors.

The Ca²⁺ dependent release was calculated by subtracting the release obtained during a 5 min period of depolarization at 200 nM free [Ca²⁺] from release at 1.33 mM CaCl₂. The Ca²⁺-dependent release of glutamate was evoked by 30 mM KCl at 1.3 mM CaCl₂ (A) or by 10 mM KCl at 0.5 mM CaCl₂ (C) in the absence (control) and presence of agonists and antagonists added at the indicated times prior to depolarization (arrows). Baclofen (20µM, 40s); tertiapin-Q (100 nM, 60s); ω-CgTx-GVIA (2µM, 100s) and ω-Aga-IVA (200 nM, 100s). B and D histograms show the % inhibition of Ca²⁺-dependent release after a 5 min depolarization under the aforementioned conditions, both in the presence of 30 mM KCl plus 1.3 mM CaCl₂ (B), or 10 mM KCl plus 0.5 mM CaCl₂ (D). Data represent the mean ± SEM (n=3–5). ^NSp>0.05; *p<0.05; **p<0.01; ***p<0.001 (students t-test) when compared with control values, unless indicated otherwise.