Formation of heme-iron complexes with nitric oxide (NO) and peroxynitrite (ONOO-) after ultraviolet radiation as a protective mechanism in rat skin.
Ultraviolet C (UVC)-irradiated microvessels isolated from rat skin release free nitrogen radicals, i.e. nitric oxide (NO), peroxynitrite (ONOO-) and nitrosocompounds formed from L-arginine. During UVC radiation of microvessels, heme (Fe3+) is released from hemoglobin and reacts with NO to form nitrosyl-heme (Fe2+-NO). The hydroxyl radical (OH*) produced is attached to heme-iron (Fe3+) to form hematin. ONOO- then binds to Fe(OH) and the complex Fe[(OH)ONOO-]2- is formed. Thus, in cases of increased oxidative stress, the free heme can act as an endogenous scavenger of OH* and ONOO-. Furthermore, Fe-NO and Fe[(OH)ONOO-]2- can act as NO donor and as antioxidant in redox cyclic iron-centered heme reactions, respectively. The scavenging-antioxidant properties of heme complexes, which allow it to protect the cells from the cytotoxic effects of the oxygen and/or nitrogen free radicals, were verified by estimating the changes in membrane fluidity of microvessels after UVC radiation. The present study indicates that UVC radiation of the skin acts as a potent stimulator for the formation of Fe-NO and Fe[(OH)ONOO-]2- in microvasculature with cytoprotective effects.
Department of Experimental Physiology, University of Athens Medical School, Athens 11527, Greece.
Stelios
S
Fotiou
Despina
D
Fotiou
George
G
Deliconstantinos
D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D001120:Arginine / Q000378:metabolism; D006418:Heme / Q000031:analogs & derivatives / Q000737:chemistry*; D006427:Hemin / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008833:Microcirculation; D009569:Nitric Oxide / Q000737:chemistry / Q000494:pharmacology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D030421:Peroxynitrous Acid / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D012867:Skin / Q000378:metabolism* / Q000528:radiation effects*; D014466:Ultraviolet Rays
D000975:Antioxidants; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; D006418:Heme; C027417:nitrosylprotoheme; D006427:Hemin; D001120:Arginine; D007501:Iron