Fig. 6. EJPs and MEJPs in variously treated preparations (A–E) and Ca2+dependence of evoked release (F).A–E, Representative traces of synaptic potential in freshly isolated preparation (A), cyclosporin A-treated (10 μm for 20 min) preparation (B), forskolin-treated (20 μm for 7 min) preparation (C), preparation with axons severed and incubated for 2 hr in HL3 medium (D), and preparation with axons severed and incubated for 2 hr in the presence of cytochalasin D (E, 10 μm). Thetopmost record in each panel shows evoked junctional potentials, and the bottom four traces show spontaneous events recorded in the same muscle fibers. MEJP records were selected to show representative amplitudes. Calibration: 8 mV, 0.1 sec (for EJPs); 1 mV, 0.2 sec (for MEJP). F, Quantal content is plotted as a function of extracellular Ca2+concentration for forskolin-treated (20 μm, filled circles), nontreated (open circles), and cyclosporin A-treated (10 μm, filled triangles) preparations. The Ca2+concentration of the recording solution was adjusted to 0.1, 0.2, 0.4, and 0.8 mm with fixed 5 mmMgCl2.