Reactive oxygen species, endothelium, lidocaine, procaine Vol. 59, No. 2, August 2010 (n = 6) and procaine (n = 8) were pretreated for 15 minutes. -87.6 ± 3.3, -77.6 ± 2.3, -65.6 ± 3.3, and 2.0 ± 1.8% with catalase, Following 35 seconds of EL to generate ROS, ACh was added. deferoxamine, sodium salicylate, and mannitol, respectively. Reagents from Sigma Co. (USA). Statistical procedure All reagents, PE, ACh, lidocaine, procaine, catalase, defeoxa- mine, sodium salicylate, mannitol, and 3AT, were purchased The degree of aortic tone relaxation by ACh was calculated as a percentage for control group values. Data are presented as mean ± SE. Prism 2.0 Ⓡ (GraphPad Software, San Diego, CA, USA) was used to obtain the dose-response curve by non-linear regression analysis. A paired t-test was used for the comparison of changes in each ring slice before and after ROS exposure, while an unpaired t-test was used for the comparison of the aortic tone after ROS exposure between the 3AT pretreated group and the non-pretreated group. For analysis of pretreated local anesthetic concentrations, a one-way ANOVA was used. All the post-hoc tests used the Dunnett test, with statistical significance as P < 0.05. Results Vascular relaxation after ROS scavenger pretreatment At ACh 10-6, the tension before ROS scavenger pretreatment was -87.6 ± 3.9%, and the endothelial-dependent relaxation was The catalsase group was not affected by ROS, but the relaxation was significantly reduced in the other groups (P < 0.05, Fig. 1). The mannitol group did not show endothelial-dependent relaxation. Vascular relaxation after endothelial injury with ROS Lidocaine dose-dependently reduced the relaxation by ACh 10-7, 3 × 10-7, and 10-6 M after ROS exposure (P < 0.05, Fig. 2 and 3). Fig. 2. Effect of low doses of lidocaine pretreatment (L-5: 10-5, L3x-5: 3 × 10-5, L-4: 10-4 M) on the reactive oxygen species (ROS) attack. Data are presented as mean ± SE. ACh: acetylcholine, EL(-): before electrolysis. *P < 0.05, compared with ACh 10-7 to 10-6 M of EL(-), †P < 0.05, compared with ACh 10-7 to 10-6 M of the lidocaine 10-5 M (L-5) group. Fig. 1. Scavengers efficiency against ROS attacks are shown in order of catalase (CAT, n = 8), deferoxamine (DEF, n = 9), and sodium salicylate (SA, n = 8). Mannitol (MN, n = 12) has no scavenging effect. Data are expressed as mean ± SE. n: number, ACh: acetylcholine, EL(-): before electrolysis. *P < 0.05, compared with ACh 10-7 to 10-6 M of EL(-), †P < 0.05, compared with ACh 10-7 to 10-6 M of the CAT group. Fig. 3. Effect of high doses of lidocaine (L3x-4: 3 × 10-4, L-3: 10-3, L3x-3: 3 × 10-3 M) on the reactive oxygen species (ROS) attack. Data are presented as mean ± SE. ACh: acetylcholine, EL(-): before electrolysis. *P < 0.05, compared with ACh 10-7 to 10-6 M of EL(-), †P < 0.05, compared with ACh 10-7 to 10-6 M of the lidocaine 10-5 M (L-5) group. 106 www.ekja.org