Figure 5.

Effect of 4-aminopyridine on intracellular Ca²⁺ release stimulated by acetylcholine in indo-1-loaded endothelial cells. Representative experimental traces showing the increase in indo-1 fluorescence ratio (F₄₀₅/F₅₀₀) evoked by acetylcholine (ACh, 1 μM) in arteries pre-incubated for 10 min in Ca²⁺-free/EGTA solution in the presence of 40 mM of K⁺. Fluorescence ratio corrected for the autofluorescence was normalized to the value measured before addition of ACh. Readmission of Ca²⁺ (Ca 1.25 mM) to the solution evoked an increase in fluorescence ratio. (A) Control condition, (B) in the presence of the thapsigargin (1 μM) and (C) in the presence of 4-aminopyridine (5 mM). (W) Indicates the washout of the artery.