Objective To investigate the effects of N-n-butyl haloperidol iodide (F2) on cAMP/PKA/ERK1/2 signaling pathway and cell injury of cardiomyocytes during extracellular calcium-free (calcium-free)-hypoxia/reoxygena-tion (H/R) in rats. Methods The calcium-free-H/R models of neonatal rat cardiomyocytes were established. And F 2 (1×10-6 mol/L) was added to normal medium, hypoxia buffer and reoxygenation buffer. Western blot analysis was used to determine the changes of phosphorylated extracellular signal-regulated kinase (p-ERK1/2), total ERK1/2 and PKA protein expressions in cardiomyocytes. Enzyme-linked immunosorbent assay (ELISA) was used to determine the level of cAMP in cardiomyocytes. Colorimetric assay was used to measure the content of LDH in the supernatant. Hoechst 33342 staining method was used to detect apoptosis in cardiomyocytes. Results Calcium-free-H/R could activate ERK1/2 in the cardiomyocytes, and therefore elevate LDH concentration in the cardiomyocytes supernatant and in-crease the apoptosis of cardiomyocytes. F2 and the ERK1/2 inhibitors U0126 and PD98059 were found to down-regu-late the high expression of calcium-free-H/R-induced ERK1/2 protein, suppress LDH leakage and reduce apoptosis. The ERK1/2 agonist EGF was found to antagonize the inhibition of F 2 on the high expression of calcium-free-H/R car-diomyocytes p-ERK1/2 and to further antagonize F2 protection. Calcium-free-H/R had no effect on the cAMP content and PKA protein expression in the cardiomycytes. Also, F 2 had no effect on the cAMP content and PKA protein ex-pression in the cultured cardiomycytes under H/R condition. Conclusion F2 can antagonize cardiomyocytes H/R in-jury through non-L-type calcium channel-independent mechanism, which may be related to its inhibition on the non-L-type calcium channel-independent ERK1/2 signaling pathway instead of the cAMP/PKA signaling pathway.%目的：研究碘化N-正丁基氟哌啶醇（F2）对大鼠心肌细胞无外钙（零钙液）缺氧/复氧（H/R）时环磷酸腺苷（cAMP）/蛋白激酶A（PKA）/细胞外信号调节激酶（ERK）1/2信号通路及细胞损伤的作用。方法建立新生大鼠心肌细胞零钙液H/R模型，于正常培养基、缺氧液和复氧液中加入F2（1×10-6 mol/L）。采用蛋白印迹法检测心肌细胞磷酸化ERK（p-ERK1/2）、总ERK1/2及PKA蛋白表达；酶联免疫吸附法（ELISA）测定心肌细胞cAMP的水平；比色法检测培养细胞上清液乳酸脱氢酶（LDH）的含量；Hoechst 33342染色法检测心肌细胞凋亡情况。结果零钙液H/R可激活心肌细胞ERK1/2，使心肌细胞培养液中LDH浓度升高，心肌细胞凋亡增加；F2和ERK1/2抑制剂U0126及PD98059可下调零钙液H/R所致p-ERK1/2蛋白高表达，抑制细胞LDH漏出，减少细胞凋亡；ERK1/2激动剂表皮生长因子（EGF）可拮抗F2对零钙液H/R心肌细胞p-ERK1/2高表达的抑制作用，进而拮抗F2的心肌保护作用。零钙液H/R对培养心肌细胞cAMP含量及PKA蛋白表达无影响，F2对零钙液H/R状态下心肌细胞cAMP含量及PKA蛋白表达无影响。结论 F2可通过非L-型钙通道依赖机制拮抗心肌细胞H/R损伤，这可能与其抑制非L型钙通道依赖的ERK1/2信号通路激活有关，但与cAMP/PKA信号通路无关。
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