Fig. 6.

Synaptic facilitation is absent in K_vβ1 KD neurons. (A–C) Average traces of pHluorin measurements of exocytosis for WT (A), K_vβ1 KD (B), and human K_vβ1 overexpressed (C) excitatory neurons in responses to 10 APs delivered at 4 Hz (black) or 50 Hz (red) as measured with vG-pH. Bars at top of the graphs indicate the duration of each stimulation. (D) Normalization of average fusion induced by the 10th AP as a percentage of total vesicle fluorescences measured by application of NH₄Cl. Neurons were stimulated with 10 AP at 4 Hz (black) or 50 Hz (red) (WT neurons, n = 16 cells; K_vβ1 KD neurons, n = 8 cells; hK_vβ1 OE neurons, n = 6 cells; *P < 0.05, paired t test). (E and F) Average traces of pHluorin measurements of exocytosis for WT (E) and hK_vβ1 overexpressed (F) inhibitory neurons in responses to 10 APs delivered at 4 Hz (black) or 50 Hz (red) as measured with vG-pH. Bars at top of the graphs indicate the duration of each stimulation. (G) Normalization of average fusion induced by the 10th AP as a percentage of total vesicle fluorescences measured by application of NH₄Cl. Neurons were stimulated with 10 AP at 4 Hz (black) or 50 Hz (red) (WT neurons, n = 7 cells; hK_vβ1 OE neurons, n = 5 cells; *P < 0.05, paired t test). Extracellular Ca²⁺ concentration is 2 mM in all experiments.