Figure 6.

Changing [Ca²⁺]_o, but not the application of baclofen, affects presynaptic Ca²⁺ transients at NGFC axonal boutons. A, Left, Fluorescence image (Alexa channel) of an NGFC (arrows indicate axonal arborization; patch pipette is seen). Right, A characteristic axonal bouton (Alexa channel; arrows, linescan position). B, Ca²⁺-dependent fluorescent transients (Fluo-4 channel) evoked by single action potentials (white line) in control (Ctrl) and after application of 10 μm baclofen (Bacl). C, Summary; action-potential-evoked ΔF/F signals were not affected by 10 μm baclofen (p > 0.70; paired t test; n = 9; data are normalized to control). Error bar represents SEM. D, Examples of action potential-evoked presynaptic Ca²⁺-dependent fluorescent transients (Fluo-4 channel, linescan) under different extracellular Ca²⁺ concentrations, as indicated. E, Normalized pooled data (average and SEM) of the action potential-evoked ΔF/F signal in the presence of 1, 2.5, and 3.5 mm extracellular Ca²⁺; the values were significantly different (**p < 0.01; ANOVA; n = 13).