Gupta Kapuganti Jagadis, Lee Chun Pong, Ratcliffe R George
Department of Plant Sciences, University of Oxford, Oxford, UK.
National Institute of Plant Genome Research, Jawaharlal Nehru University, Delhi, India.
Plant Cell Physiol. 2017 Jan 1;58(1):175-183. doi: 10.1093/pcp/pcw174.
Oxygen deprivation leads to changes in mitochondrial morphology and impaired flow of reducing equivalents through the electron transport chain. The extent of these changes depends on the duration and severity of the treatment as well as on the species and cell type. Nitrate is known to ameliorate these effects in some instances, but it is possible that it is nitrite, rather than nitrate, that is the key to the mechanism. To test this, mitochondria were isolated from 21-day-old pea (Pisum sativum) roots and incubated for 90 min under normoxia or hypoxia in the presence or absence of 0.5 mM nitrite. The supply of nitrite under hypoxia led to nitric oxide production, improved mitochondrial integrity, improved energization of the inner mitochondrial membrane, increased ATP synthesis, decreased production of reactive oxygen species and decreased lipid peroxidation. It also resulted in higher levels and activities of complex I and the supercomplex I + III2. It is concluded that nitrite has an important role in maintaining mitochondrial function under hypoxia, and that it achieves this through the reduction of nitrite to nitric oxide by the mitochondrial electron transport chain.
缺氧会导致线粒体形态发生变化，并损害还原当量通过电子传递链的流动。这些变化的程度取决于处理的持续时间和严重程度，以及物种和细胞类型。已知硝酸盐在某些情况下可改善这些影响，但有可能是亚硝酸盐而非硝酸盐是该机制的关键。为了验证这一点，从21日龄豌豆（Pisum sativum）根中分离出线粒体，并在常氧或缺氧条件下，在有或没有0.5 mM亚硝酸盐的情况下孵育90分钟。缺氧条件下亚硝酸盐的供应导致一氧化氮的产生，改善了线粒体完整性，改善了线粒体内膜的能量化，增加了ATP合成，减少了活性氧的产生并减少了脂质过氧化。它还导致复合物I和超复合物I + III2的水平和活性更高。得出的结论是，亚硝酸盐在缺氧条件下维持线粒体功能中起重要作用，并且它通过线粒体电子传递链将亚硝酸盐还原为一氧化氮来实现这一点。
