Figure 2.

[CCh*]_local does not affect Ca²⁺ currents. (A) Experimental protocol. (A₁) The ENTC (dashed square) and the resultant EPSC. (A₂) The ENTC on a larger scale. (A₃) The ENTC after addition of 100 µM Cd²⁺. (A₄) Net Ca²⁺ current obtained after subtracting the current seen in A₃ from the ENTC. (B–G) Bars in the bottom of each column apply to that entire column. (B and C) Representative example (n = 3) of ENTCs and EPSCs (B) and Ca²⁺ currents (C) measured with a full action potential (dashed line) and with 50 nM TTX (solid line; i.e., smaller action potential). (D–G) In the presence of 50 nM TTX. (D and E) Representative example (n = 5) of ENTCs and EPSCs (D) and Ca²⁺ currents (E) measured before (solid line) and 1 ms after (dashed line) the flash ([CCh*]_local = 12 µM). [CCh*]_local reduced release to 19% of control without affecting Ca²⁺ currents. (F and G) ENTCs and EPSCs (F) and Ca²⁺ currents (G) with the same flash in normal [Mg²⁺]_o (1 mM; long dashed line) and with elevated [Mg²⁺]_o (5 mM; short dashed line). Representative example, n = 3.