Figure 4. Activation of mAChRs does not enhance Ca_V2.3 mediated Ca influx into active spines.

A, top, Voltage-step protocol showing 300 ms steps to −50, −40, −30, −20, −10, 0, +10, +20 and +30 mV from a holding potential of −70 mV. bottom, Example series of fluorescence transients evoked by steps to the indicated potentials measured in line scans intersecting a spine head (sp) and neighboring dendrite (den).

B, top, Average fluorescence transients measured as in panel A showing depolarization-dependent Ca influx into the spine head in control (black) and in the presence of SNX-482 (green). bottom, summary data for Δ[Ca]_spine measured as in panel A in control (black) and SNX-482 (green).

C, top, Average fluorescence transients for voltage steps to 0 mV in control (black) and SNX-482 (green). bottom, as above, but in the presence of oxo-m (red) and SNX-482+oxo-m (orange).

D, Summary of ΔG/G_sat in response to voltage-steps to 0 mV measured in the four pharmacological conditions shown in C. * indicates significantly different from the corresponding SNX-482 lacking condition.

E, Image of a spine and dendrite (top, left) and an example of fluorescence collected during line scan (top, right) indicated by the dashed yellow. Overlaid on the line scan fluorescent image is the action potential recorded at the soma (top) and the quantification of the ΔG_bap/G_sat from the spine head (bottom). bottom, average ΔG_bap/G_sat from the spine head measured in control (black), SNX-482 (green), oxo-m (red), and oxo-m+SNX-482 (orange)

F, Summary of ΔG_bap/G_sat amplitude for the four pharmacological conditions shown in D. * indicates significantly different from the corresponding SNX-482 lacking condition.