Mechanisms of extracellular hydrogen peroxide clearance by alveolar type II pneumocytes.
Mechanisms of extracellular hydrogen peroxide clearance by alveolar type II pneumocytes.
复制标题
肺泡 II 型肺细胞清除细胞外过氧化氢的机制。
DOI：
10.1152/jappl.1990.69.6.2078
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Matalon,S
中科院分区：
文献类型：
--
作者：
Engstrom,PC;Easterling,L;Baker,RR;Matalon,S
本研究量化了新鲜分离的肺泡II型（ATII）肺细胞减少细胞外产生的过氧化氢（H2 O2）的能力，并确定了相关机制。通过酶消化和Percoll离心从兔肺中分离高纯度（大于85%）的ATII细胞，并将其悬浮在Eagle最低必需培养基（MEM）中。然后将它们与500 μ M黄嘌呤和10 mU/ml黄嘌呤氧化酶（XO; pH 7.4; 25 ℃）或300 μ M H2 O2共孵育。在以下条件下测量60分钟内的细胞外H2 O2浓度[H2 O2]：1）单独的MEM，2）未处理（对照），3）3-氨基-1，2，4-三唑（ATZ）处理，或4）1-氯-2，4-二硝基苯处理的ATII细胞。在MEM中单独添加黄嘌呤和XO导致[H2 O2]呈时间依赖性增加，45分钟后达到约300 μ M的平台值。在对照ATII细胞（1 × 10（6）个细胞/ml）存在下，[H2 O2]保持在对照水平。当与300 μ M H2 O2共孵育时，ATII细胞以高于等量游离过氧化氢酶的速率清除H2 O2。与ATZ一起孵育可使ATII细胞过氧化氢酶活性降低89%，并显着损害其清除H2 O2的能力（半衰期= 18.1 +/- 2.7 vs. 1.3 +/- 0.1 min，P小于0.01）。ATZ处理的细胞更容易受到氧化损伤，如所示的能力下降，排除台盼蓝60分钟后的H2 O2暴露。另一方面，谷胱甘肽耗尽的细胞清除过氧化氢在相同的速度作为控制。（250字处删节）
This study quantified the ability of freshly isolated alveolar type II (ATII) pneumocytes to reduce extracellularly produced hydrogen peroxide (H2O2) and identify the mechanisms involved. ATII cells were isolated to high purity (greater than 85%) from rabbit lungs by enzymatic digestion and Percoll centrifugation and suspended in Eagle's minimum essential medium (MEM). They were then coincubated with either 500 microM xanthine and 10 mU/ml xanthine oxidase (XO; pH 7.4; 25 degrees C) or 300 microM H2O2. The extracellular H2O2 concentration [H2O2] was measured in the following conditions over a 60-min period: 1) MEM alone, 2) untreated (control), 3) 3-amino-1,2,4-triazole (ATZ)-treated, or 4) 1-chloro-2,4-dinitrobenzene-treated ATII cells. Addition of xanthine and XO to MEM alone resulted in a time-dependent increase in [H2O2], reaching a plateau value of approximately 300 microM after 45 min. In the presence of control ATII cells (1 x 10(6) cells/ml), [H2O2] remained at control levels. When coincubated with 300 microM H2O2, ATII cells cleared H2O2 at a higher rate than an equivalent amount of free catalase. Incubation with ATZ decreased ATII cell catalase activity by 89% and significantly impaired their ability to clear H2O2 (half-life = 18.1 +/- 2.7 vs. 1.3 +/- 0.1 min, P less than 0.01). ATZ-treated cells were more susceptible to oxidant injury, as shown by their decreased ability to exclude trypan blue after 60 min of H2O2 exposure. On the other hand, glutathione-depleted cells scavenged H2O2 at the same rate as controls.(ABSTRACT TRUNCATED AT 250 WORDS)