Lipoxygenase-dependent superoxide release in skeletal muscle

• Published in: Journal of applied physiology (1985) Vol. 97; no. 2; pp. 661 - 668
• Main Authors: Zuo, Li, Christofi, Fievos L, Wright, Valerie P, Bao, Shengying, Clanton, Thomas L
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.08.2004; American Physiological Society
• Subjects: 5,8,11,14-Eicosatetraynoic Acid - pharmacology; Animals; Arachidonate 12-Lipoxygenase - metabolism; Arachidonate 5-Lipoxygenase - metabolism; Arachidonic Acid - metabolism; Biological and medical sciences; Caffeic Acids - pharmacology; Cyclooxygenase Inhibitors - pharmacology; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Heat; Indomethacin - pharmacology; Lipoxygenase Inhibitors; Male; Metabolism; Muscle, Skeletal - enzymology; Muscular system; Proadifen - pharmacology; Rats; Rats, Sprague-Dawley; Stress; Superoxides - metabolism; arachidonic acid; heat stress; Vertebrata; Mammalia; Enzyme; Oxidoreductases; Lipoxygenase; Striated muscle; cytochrome c; hydroethidine; manoalide; Release
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/japplphysiol.00096.2004

1 Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Dorothy M. Davis Heart and Lung Research Institute, and 2 Department of Anesthesiology, The Ohio State University, Columbus, Ohio 43210 Submitted 2 February 2004 ; accepted in final form 2 April 2004 Superoxide anion radical (O 2 – ) is released from skeletal muscle at rest and is particularly elevated during conditions of heat stress (42°C). Previous studies have shown that in isolated rat diaphragm O 2 – release is not dependent on mitochondrial electron transport, reduced NADP oxidase activity, or the integrity of membrane anion channels. This study hypothesized that O 2 – release, as measured by cytochrome c reduction, is linked to metabolism of arachidonic acid. Phospholipase A 2 inhibition with manoalide significantly decreased O 2 – release. In downstream pathways, neither the blockage of cyclooxygenase with indomethacin nor the inhibition of cytochrome P -450-dependent monooxygenase with SKF-525A decreased O 2 – release. However, lipoxygenase (LOX) inhibition with general LOX blockers 5,8,11,14-eicosatetraynoic acid and cinnamyl-3,4-dihydroxy- -cyanocinnamate greatly attenuated the signal. Furthermore, the specific 5-LOX inhibitor diethylcarbamazine also significantly decreased O 2 – release. Immunohistochemistry localized 5- and 12-LOX to the cytosol and sarcolemma of muscle cells. Confocal studies, using the O 2 – -sensitive fluorescent indicator hydroethidine, demonstrated that LOX inhibition had no significant influence on intracellular O 2 – formation. When compared with the cytochrome c results, this indicates that intra- and extracellular O 2 – must arise from different sources. These data show for the first time that arachidonic acid metabolism through LOX activity, is a major source of extracellular O 2 – release in skeletal muscle. manoalide; hydroethidine; arachidonic acid; cytochrome c ; heat stress Address for reprint requests and other correspondence: T. Clanton, The Ohio State Univ., Pulmonary and Critical Care Medicine, 201 Dorothy M. Davis Heart and Lung Research Institute, 473 W 12th Ave., Columbus, OH 43210 (E-mail: clanton.1{at}osu.edu ).