Piantadosi C A
Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710.
Am J Physiol. 1989 Apr;256(4 Pt 1):C840-8. doi: 10.1152/ajpcell.1989.256.4.C840.
Terminal oxidase inhibitors such as cyanide (CN) and carbon monoxide (CO) produce different absorption changes in the intact brain, suggesting different mitochondrial responses to the inhibitors. In the present study, the nature of the cytochromes involved in CO and CN responses in vivo was investigated by low-temperature spectroscopy of rat brain, frozen in situ, and of preparations of brain homogenate and isolated mitochondria. Comparison of the spectra from different preparations at the high resolution afforded by low-temperature spectroscopy indicated that absorption responses to CO in vivo originated from mitochondrial b cytochromes. Further detailed spectral analysis of mitochondrial preparations revealed three CN-insensitive b cytochromes in nonsynaptic brain mitochondria; one cytochrome could be reduced by succinate in the presence of CN, the second could be reduced by succinate plus ATP, and the third could be reduced only by anaerobiosis. The spectral characteristics of the mitochondrial b cytochromes, when compared with spectra from CO-exposed brain tissue frozen in situ, strongly implicated the energy-dependent cytochrome b in the oxidation-reduction (redox) responses caused by CO in vivo.
诸如氰化物（CN）和一氧化碳（CO）等末端氧化酶抑制剂会在完整大脑中产生不同的吸收变化，这表明线粒体对这些抑制剂有不同的反应。在本研究中，通过对原位冷冻的大鼠大脑、脑匀浆制剂和分离的线粒体进行低温光谱分析，研究了体内参与CO和CN反应的细胞色素的性质。低温光谱提供的高分辨率下不同制剂光谱的比较表明，体内对CO的吸收反应源自线粒体b细胞色素。对线粒体制剂的进一步详细光谱分析揭示了非突触性脑线粒体中有三种对CN不敏感的b细胞色素；一种细胞色素在存在CN的情况下可被琥珀酸还原，第二种可被琥珀酸加ATP还原，第三种仅在厌氧条件下可被还原。将线粒体b细胞色素的光谱特征与原位冷冻的暴露于CO的脑组织的光谱进行比较时，强烈表明能量依赖性细胞色素b参与了体内CO引起的氧化还原（redox）反应。
