Fig. 3.

Inhibition of presynaptic voltage-dependent Ca²⁺ channels decreased synaptic transmission and relieved synaptic depression. A, C, and E: frequency-dependent decrease of steady-state eEPSC amplitude (pA) during 0.08–25 Hz optic chiasm stimulation with trains of 25 stimuli in control and following application of N- and P/Q-type voltage-dependent Ca²⁺ channel blockers: ω-conotoxin GVIA (1 μM) and ω-agatoxin TK (500 nM), respectively. A: ω-agatoxin (Atx, n = 6). C: ω-conotoxin (Ctx, n = 7). E: coapplication of Atx and Ctx (n = 3). B, D, and F: the same data as in A, C, and E normalized (%) to the amplitude of the first eEPSC in the stimulus train at each condition (see Fig. 1). *P < 0.05, ***P < 0.001.