Although most of the O2 delivered to the lung diffuses into the blood and is ultimately utilized by other tissues, the lung itself requires O2 for both energy metabolism and cellular signaling. The greatest use of O2 by lung cells, as typical cells, is in the generation of adenosine triphosphate (ATP). For this reason, we will focus a large part of this discussion on the mechanisms for generating ATP, rather than just on the more narrow area of cytochrome c oxidase activity. The lung is also the site of a number of other important biochemical roles for O2. These include the transformation of steroids and xenobiotics by cytochrome P450 and flavin monooxygenase; the production of nitric oxide; the oxidation of amines, such as serotonin; the formation of collagen and elastin cross-links by oxidative processes; the production of prostaglandins, leukotrienes, and related arachidonate metabolites; and the oxidative killing of microorganisms by phagocytes. Oxygen is used to generate hydrogen peroxide for cell signaling. While low in quantitative terms, this oxygen consumption, primarily from nicotinamide adenine dinucleotide phosphate oxidases and possibly by mitochondria, is very significant physiologically. Finally, we will briefly consider the role of enzymes involved with eliminating the toxic byproducts of the reactions listed above. Our primary aim here, however, is to describe the normal O2 metabolism of the lung.
|Title of host publication||Comparative Biology of the Normal Lung: Second Edition|
|Number of pages||20|
|Publication status||Published - 18 Mar 2015|
- Cytochrome P450
- Peroxide signaling
ASJC Scopus subject areas
- Pharmacology, Toxicology and Pharmaceutics(all)