Figure 2: GABA-induced somatic Ca2+ transients in the presence of BayK 8644 in vivo.
From: GABA depolarizes immature neurons and inhibits network activity in the neonatal neocortex in vivo
(a) Experimental arrangement. (b,e,i,m) Two-photon fluorescence images of OGB1-stained CP cells in vivo. Scale bars, 10 μm; bv, blood vessel. (c) Single-cell Ca2+ responses to puff-applied glutamate (Glu; 100 mM, 0.3 s) and GABA (100 mM, 0.3 s). Scale bars, 1.5 ΔF/F0, 2.5 s. (d) ΔF/F0 amplitude distributions. Each symbol represents a single cell (n=204 cells, five mice). (f) GABA-induced Ca2+ responses in the absence (Control) and presence of BayK 8644 (20 μM). Scale bars, 0.5 ΔF/F0, 5 s. (g) ΔF/F0 amplitude distributions (n=126 cells, four mice). (h) The mean ΔF/F0 amplitudes per animal (P<0.01, n=4 mice, paired t-test). (j) Ca2+ responses (averages from 12 cells shown in i) to GABA (100 mM), Muscimol (Musci, 5 mM), Baclofen (Baclo, 5 mM) and ACSF. Note differences in time-axis scaling. Scale bars, 0.25 ΔF/F0, 5 s. (k) ΔF/F0 amplitude distributions (GABA: n=172 cells; Muscimol: n=139 cells; Baclofen: n=172 cells; ACSF: n=139 cells). (l) The mean ΔF/F0 amplitudes per animal (GABA: P<0.05, n=6 mice; Muscimol: P<0.01, n=5 mice; Baclofen: P>0.95, n=6 mice; ACSF: P>0.4, n=5 mice; one-sample Wilcoxon-signed rank tests). (n) GABA-induced Ca2+ responses were sensitive to bumetanide (50 μM). Scale bars, 0.25 ΔF/F0, 5 s. (o) Single-cell GABA-induced ΔF/F0 amplitude distributions (n=122 cells, six mice). (p) The mean GABA-induced ΔF/F0 amplitudes per animal (normalized to control). GABA-induced Ca2+ transients did not require voltage-gated Na+ channels (TTX: P>0.15, n=5 mice) but were sensitive to antagonists of voltage-gated Ca2+ channels (TTX+CdCl2: P<0.05, n=4 mice, Bonferroni-corrected paired t-tests), NKCC1 (Bumetanide: n=6; repeated-measures ANOVA: P<0.001, Bonferroni test: P<0.01) and GABAA receptors (Picrotoxin: P<0.001, n=7; paired t-test). Picrotoxin and bumetanide were tested in the presence of TTX. (i–p) Experiments were performed in the presence of BayK 8644. (h,l,p) Data presented as mean±s.e.m. *P<0.05, **P<0.01, ***P<0.001, n.s., not significant.
