Biologia, Bratislava, 55/Suppl. 8: 49-53, 2000.

ISSN 0006-3088 (Biologia). ISSN 1335-6399 (Biologia. Section Cellular and Molecular Biology).

 

Review

Oxygenation of arachidonic acid under hypoxic conditions: some methodological aspects and possible biological relevance.

 

Ivo Juranek* & Vladimir Rekalov

Institute of Experimental Pharmacology, Slovak Academy of Sciences, Dubravská cesta 9, SK-84216 Bratislava, Slovakia; e-mail: exfaivo@savba.sk

* corresponding author

Received: July 10, 2000 / Accepted: October 24, 2000

 

Abstract

Hypoxia has been shown to alter the arachidonic acid cascade in various tissues. Once released, arachidonic acid is immediately metabolized through lipoxygenase (LOX) and/or cyclooxygenase (COX) pathways. LOX incorporates one molecule of oxygen at various carbon atoms of arachidonic acid, yielding respective hydroperoxy-eicosatetraenoic acids, while COX inserts two molecules of oxygen into the fatty acid substrate, producing prostaglandin G2. Thus, molecular oxygen, as the second substrate of the LOX- and COX-mediated arachidonate oxygenation, is absolutely required at the first step of the arachidonic acid cascade. Previously, LOXs and COXs of mammalian origin have been broadly studied with regard to their fatty acid substrate specificity, and recently, their affinities to molecular oxygen were evaluated. Data of the oxygen dependency of these enzymes may help to understand their functions and an involvement of the respective arachidonic acid-derived metabolites in cellular biology. That may elucidate mechanisms of hypoxia-induced alterations of tissue functions mediated by various eicosanoids. Findings about the affinities of the arachidonate oxygenases for molecular oxygen together with the knowledge of oxygen concentration in the tissue are used as basic information for the in vivo implication of eicosanoid synthesis under hypoxic conditions.

 

Key words: arachidonic acid, hypoxia, lipoxygenase, cyclooxygenase.