Essential role of complex II of the respiratory chain in hypoxia-induced ROS generation in the pulmonary vasculature.

In the pulmonary vasculature, the mechanisms responsible for oxygen sensing and the initiation of hypoxia-induced vasoconstriction and vascular remodeling are still unclear. Nitric oxide (NO) and reactive oxygen species are discussed as early mediators of the hypoxic response. Here, we describe a quantitative analysis of NO- and cells within the vascular walls of murine lung sections cultured at normoxia or hypoxia. Whereas the number of NO-producing cells was not changed by hypoxia, the number of cells was significantly increased. Addition of specific inhibitors revealed that mitochondria were the source of The participation of the individual mitochondrial complexes differed in normoxic and hypoxic generation. Whereas normoxic duanyu1670 production required complexes I and III, hypoxic duanyu1670 generation additionally demanded complex II. Histochemically demonstrable succinate dehydrogenase activity of complex II in the arterial wall decreased during hypoxia. Inhibition of the reversed enzymatic reaction, i.e., fumarate reductase, by application of succinate, specifically abolished hypoxic, but not normoxic, duanyu1670 generation. Thus complex II plays an essential role in hypoxic duanyu1670 production. Presumably, its catalytic activity switches from succinate dehydrogenase to fumarate reductase at reduced oxygen tension, thereby modulating the directionality of the electron flow.

KEYWORDS: {{ getKeywords(articleDetailText.words) }}