Journal: Journal of Neurophysiology
Article Title: Impact of spatiotemporal calcium dynamics within presynaptic active zones on synaptic delay at the frog neuromuscular junction
Figure Lengend Snippet: Role of VGCC density on synaptic delay. A: schematic representing manipulation of the density of VGCCs. B: average simulated synaptic delays when there are 52, 26 (control model), 13, or 4 VGCCs in the model AZ. All comparisons made to the 26 VGCC configuration: 52 VGCCs: P < 0.001; 13 VGCCs: P = 0.035; 4 VGCCs: P = 0.002; 2-sided bootstrap test, α = 0.001 with Bonferroni correction; n = 100,000 bootstrap repetitions of average simulated synaptic delay. C: average synaptic delays measured from an ex vivo frog NMJ preparation before and after application of 600 nM conotoxin (CgTx) GVIA; P < 0.05, 2-sided paired t-test, α = 0.05, degrees of freedom = 31; n = 32 pairs. D: spatiotemporal calcium profile within the sampling box beneath synaptic vesicles triggered to fuse. E: expansion of the time base to illustrate the 10–90% rise of the calcium profile plotted in D with best fit lines in light gray. Comparisons were made to the best fit line to the control (26 VGCC displacement) model, 2-sided sum of squares F-test with Bonferroni correction: 52 VGCCs: P < 0.001; 13 VGCCs: P < 0.001; 4 VGCCs: P < 0.001; α = 0.001, n = 2,000 seeds for each condition. F: % calcium ion contributions from specific VGCCs to total bound calcium ions on vesicles triggered to fuse (denoted by large filled circle) for simulations with 4, 13, 26 (control model), or 56 VGCCs in the AZ (calculated as described for Fig. 2). All comparisons made to the main channel in the 26 VGCC configuration: 52 VGCCs: P < 0.001; 13 VGCCs: P = 0.004; 4 VGCCs: P < 0.001; 2-sided bootstrap test with Bonferroni correction, α = 0.001, n = 100,000 bootstrap repetitions of average ratio of calcium ions contributed to release. *Significant difference.
Article Snippet: Before recording, preparations were bathed in µ-conotoxin PIIIA (Alomone Laboratories) to prevent most muscle contraction, with any residual contractions further blocked by inclusion of 0.1–0.5 µM tubocurarine chloride hydrate (Sigma-Aldrich) in the bath during recording.
Techniques: Ex Vivo, Sampling