Ca²⁺ oscillations persist after selective VGCC blockade.

<p><b>A</b> A ventral horn neuron was whole-cell voltage clamped at −90 mV and stepped (10 mV increments) in TTX (1 µM), TEA (5 mM), and 4-AP (1 mM). Step-induced VGCC current (Ai, top) is blocked by ω-CgTxMVIIC (Ai, bottom; 5 µM). A pooled I-V plot shows the significant reduction of whole-cell VGCC current (Aii, solid line) after application of ω-CgTxMVIIC (Aii, dashed line, 5 µM). Red line and traces denote −40 mV, the average peak of membrane potential oscillations. Error bars express ± SEM. <b>B</b> A ventral horn neuron was whole-cell voltage clamped and filled with OGB1 (Biii, 25 µM) at −70 mV. In current clamp mode, application of NMDA (50 µM) and TTX (1 µM) induced simultaneous, repetitive oscillations in membrane potential (Bi) and Ca²⁺ dye fluorescence (Bii, black), which persisted in ω-CgTxMVIIC (Bi-ii; 5 µM). White box denotes region of interest from which measurements in Bii were taken. Red line denotes −40 mV, the average peak of membrane potential oscillations. Scale bar = 50 µm.