目的:观察不同氧分压对大鼠肾上腺髓质嗜铬瘤(pheochromocytoma, PC12)细胞生存的影响，探讨可能的机制。方法:PC12细胞长满培养瓶底70%～80%时随机分为0.1 MPa组、0.2 MPa组和0.4 MPa组，分别置于实验舱中，0.1 MPa组常压下呼吸纯氧，另2组升压速度0.03 MPa/min，稳压在相应压力下予纯氧1 h。用四甲基偶氮唑[3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide，MTT]比色法测定细胞存活率、培养液中乳酸脱氢酶(L-lactate dehydrogenase，LDH)水平，流式细胞仪检测细胞内活性氧(reactive oxygen species，ROS)及线粒体膜电位(mitochondrial membrane potential，MMP)。结果:(1)0.2 MPa组较0.1 MPa组细胞存活率升高[(118.35±5.42 )%n vs. (100.38±5.08)%)，差异具有统计学意义(n P<0.01)，而0.4 MPa组的细胞存活率[(83.50±7.11)%]较0.1 MPa组及0.2 MPa组降低，差异有统计学意义(n P<0.01)。(2)0.4 MPa组内的LDH水平(1 071.67±35.36)明显增加，与0.1 MPa组(959.19±34.06)和0.2 MPa组(966.66±31.38)比较，差异均具有统计学意义(n P<0.01)。(3)ROS水平随着压力的增加而上升，0.1 MPa组(97.48±6.08)和0.2 MPa组(112.48±3.14)、0.1 MPa组和0.4 MPa组(148.62±4.79)、0.2 MPa组与0.4 MPa组的ROS水平差异均具有统计学意义(n P<0.01)。(4)Rh123的荧光强度与MMP负相关，3组分别为(797.63±60.05)、(798.20±58.54)、(1 362.32±40.68)，0.2 MPa组的MMP与0.1 MPa组相比，差异无统计学意义(n P＝0.79)，0.4 MPa组的MMP较0.1 MPa组及0.2 MPa组降低，差异有统计学意义(n P<0.01)。n 结论:适当的氧分压增加PC12细胞的存活率，过高的氧分压对细胞产生毒性作用，产生过量ROS，引起MMP降低可能是机制之一。“,”Objective:To observe the effect of different oxygen partial pressure on the survival of adrenal medullary pheochromocytoma (PC12) cells in rats and explore the possible mechanism.Methods:When carpeting 70%-80% of the entire flask bottom, the PC12 cells were randomly divided into 0.1 MPa group, 0.2 MPa group, and 0.4 MPa group. Then each group was placed in the experiment chamber respectively. The 0.1 MPa group was given pure oxygen under normal pressure in which oxygen partial was 0.1 MPa; while the other two groups was given 0.2 MPa and 0.4 MPa partial pure oxygen respectively with 0.03 MPa/min compresing and decompressing. Pure oxygen was given for 1 h under the corresponding stable pressure. Cell viability and the level of L-lactate dehydrogenase (LDH) in cultrue solution were determined by 3-(4, 5-dimethylthiazol-2yl)-2, 5-diphenyl tetrazolium bromide (MTT) colorimetric assay, intracellular reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were detected by flow cytometry.Results:(1) The cell viability in the 0.2 MPa group (118.35±5.42)% was significantly higher than that in the 0.1 MPa group (100.38±5.08)% (n P<0.01), while the cell viability in the 0.4 MPa group (83.50±7.11)% was lower than those in the 0.1 MPa group and the 0.2 MPa group (n P<0.01). (2) The level of LDH in the 0.4 MPa group (1 071.67±35.36) was significantly increased, which was significantly different from those in the 0.1 MPa group (959.19±34.06) and the 0.2 MPa group (966.66±31.38) (n P<0.01). (3) The level of ROS rised as the oxygen partial pressure increased. The differences of ROS level between the groups, i. e. the 0.1 MPa group (97.48±6.08) and the 0.2 MPa group (112.48±3.14), the 0.1 MPa group and the 0.4 MPa group (148.62±4.79), and the 0.2 MPa group and the 0.4 MPa group, were all statistically significant (n P<0.01). (4) The fluorescence intensity of Rh123 in each group were (797.63±60.05), (798.20±58.54), and (1 362.32±40.68) respectively, which were negatively correlated with MMP. There was no significant difference in MMP between the 0.1 MPa group and the 0.2 MPa group (n P=0.79), but the MMP in the 0.4 MPa group was lower than those in 0.1 group and the 0.2 MPa group with statistical significance (n P<0.01).n Conclusion:The appropriate oxygen partial pressure could increase the viability of PC12 cells while a high oxygen partial pressure may be toxic, produce excessive ROS, and then induce the decrease of MMP, which is one of the possible mechanisms.