外源NO协同N-乙酰半胱氨酸对肥城桃果实线粒体抗氧化系统的调控作用

Regulation by Exogenous Nitric Oxide and N-acetyl-L-cysteine on Mitochondrial Antioxidant System in Feicheng Peaches

探讨外源NO和N-乙酰半胱氨酸对冷藏期间肥城桃果实线粒体抗氧化系统的影响。分别用15μmol/L NO溶液,80 mmol/L N-乙酰半胱氨酸(N-acetyl-L-cysteine,NAC,活性氧清除剂)和15μmol/L NO的混合溶液,5μmol/L的c-PTIO(NO清除剂)溶液对肥城桃果实进行浸果处理,测定果实冷藏期间线粒体呼吸、线粒体膜电势、线粒体中丙二醛和活性氧含量及抗氧化酶活性的变化。15μmol/L NO处理显著降低了桃果实线粒体ROS的含量;80 mmol/L NAC-15μmol/L NO处理桃果实线粒体ROS含量在第2周后显著低于对照和其他处理;而5μmol/L c-PTIO处理桃果实线粒体ROS含量显著高于其他处理。在抗氧化酶(POD、SOD、CAT)活性测定中,15μmol/L NO处理提高了桃果实线粒体中抗氧化酶的活性,高于对照和5μmol/L c-PTIO处理;80 mmol/L NAC-15μmol/L NO处理能够提高SOD的活性,但对于POD和CAT的活性有抑制作用;而5μmol/L c-PTIO处理抑制桃果实线粒体中抗氧化酶的活性。15μmol/L NO处理降低了桃果实线粒体中MDA含量,除第2周均低于对照和其他处理外;80 mmol/L NAC-15μmol/L NO处理桃果实线粒体MDA含量在第1周后显著高于对照和其他处理;而5μmol/L c-PTIO处理桃果实在第2,3周时线粒体中MDA含量高于对照和15μmol/L NO处理。15μmol/L NO处理能够提高线粒体膜电势,在第3周时到达最大值,是对照的1.2倍;80 mmol/L NAC-15μmol/L NO处理桃线粒体膜电势最高,高于对照和其他处理;而5μmol/L c-PTIO处理降低了线粒体膜电势,显著低于对照和其他处理。15μmol/L NO处理抑制了桃线粒体呼吸;80 mmol/L NAC-15μmol/L NO处理使线粒体呼吸高峰提前1周;而5μmol/L c-PTIO处理提高了线粒体呼吸高峰,耗氧量大于对照和其他处理。外源NO和NAC处理能够提高桃果实线粒体抗氧化系统的抗氧化能力,延缓桃果实线粒体功能的下降。

To study the regulation by exogenous nitric oxide（ NO） and N-acetyl-L-cysteine（ NAC） on mitochondrial antioxidative system of Feicheng peaches during cold storage. Feicheng peaches were dipped in15 μmol/L NO,80 mmol/L N-acetyl-L-cysteine（ NAC,reactive oxygen species scavenger） plus 15 μmol/L NO,and 5 μmol/L c-PTIO（ NO scavenger） solution,respectively. The changes in mitochondrial respiration,mitochondrial membrane potential,the contents of malonaldehyde（ MDA） and reactive oxygen species（ ROS） and the activities of antioxidant enzymes were detected. Treatment with 15 μmol/L NO significantly decreased mitochondrial ROS content. Especially at the 1 st week,mitochondrial ROS content in peaches treated with 15 μmol/L NO was only 50% of the control. Mitochondrial ROS content in peaches treated with 80 mmol/L NAC-15 μmol/L NO was significantly lower than that of the control and other treatments after 2 weeks,while treatment with 5 μmol/L c-PTIOincreased the content of mitochondrial ROS. The activities of antioxidative enzymes（ POD,SOD and CAT） in mitochondria of peaches treated with 15 μmol/L NO was higher than that of the control and treatment with 5 μmol/L cPTIO. Treatment with 80 mmol/L NAC-15 μmol/L NO increased the activity of mitochondrial SOD and decreased the activities of mitochondrial POD and CAT. Treatment with 5 μmol/L c-PTIO decreased the activities of antioxidative enzymes in mitochondria. Mitochondrial MDA content in peaches treated with 15 μmol/L NO was lower than that of the control and other treatments during the storage except for the second week. However,mitochondrial MDA content in peaches treated with 80 mmol/L NAC-15 μmol/L NO was significantly higher than that of the control and other treatments after 1 week. Mitochondrial MDA content in peaches treated with 5 μmol/L c-PTIO was higher than that of the control and treatment with 15 μmol/L NO in the second and third week. Mitochondrial membrane potential was improved by treatment with 15 μmol/L NO,reached the maximum,which was 1. 2 times as high as that of the control,at 3 weeks. Mitochondrial membrane potential of peaches treated with 80 mmol/L NAC-15μmol/L NO was higher than that of the control and other treatments. However,treatment with 5 μmol/L c-PTIO decreased mitochondrial membrane potential. The mitochondrial respiration of peaches was inhibited by treatment with15 μmol/L NO. Mitochondrial respiration peak of peaches treated with 80 mmol/L NAC-15 μmol/L NO appeared1 week earlier than the control. Treatment with 5 μmol/L c-PTIO maintained high respiration of mitochondria. Exogenous nitric oxide and N-acetyl-L-cysteine could improve the antioxidant capacity of mitochondrial antioxidant system of peaches during storage,and delay the decrease of mitochondrial function.