Propofol (10, 30, and 100 μM) inhibits the norepinephrine release triggered by high K⁺ and facilitates the norepinephrine release by ionomycin in a concentration-dependent manner. Propofol: dissolved in dimethyl sulfoxide (DMSO), the final concentration of DMSO is lower than 0.1%. Error bars indicate SD (n = 6). One-way ANOVA with repeated measures revealed significant, dose-dependent effects of propofol on norepinephrine release in physiological saline solution (PSS; P < 0.0001; 100 μM propofol stimulated significantly higher release than others based on post hoc Bonferroni test, P < 0.05), high K⁺ (P < 0.0001; post hoc test showed significant differences in all the paired comparisons, P < 0.05), or ionomycin (P < 0.0001; post hoc test showed significant differences in all the paired comparisons except for DMSO versus 10 μM propofol, P < 0.05). *P < 0.05, and n.s. indicates not significant at P = 0.05 level. High K⁺ = 70 mM potassium chloride (KCl); ionomycin = 1 μM.