Figure 5. The effects of T-type Ca²⁺ channel blockers on EJPs and NCTs.

A and B show the effect of Ni²⁺ or mibefradil (respectively) on EJPs during low frequency (0.33 Hz) stimulation. The recordings were zeroed with respect to the potential recorded by the microelectrode outside the cell at the end of each experiment. The sampling frequency in A is 100 Hz, while that in B is 4 kHz. The amplitudes of NCTs under control conditions and in the presence of either NiCl₂ (100 µm; C) or mibefradil (10 µm; D) are also shown. Each point represents the amplitude of NCTs occurring at a single neuroeffector junction. A line of equivalence (where the amplitudes are unchanged) is marked on each graph. At concentrations specific for T-type Ca²⁺ channel block, neither of these drugs significantly affects the amplitude of EJPs or NCTs.