Interaction of singlet oxygen with 5'-nucleotidase in rat hearts.
This study was aimed to determine whether singlet oxygen (1O2) attenuates 5'-nucleotidase activity in the ischemic myocardium. Isolated rat hearts were exposed to either exogenous 1O2 produced by irradiating rose bengal or 40-min ischemia and reperfusion. Ecto-5'-nucleotidase activity was inhibited by exogenous 1O2 (3.74 +/- 0.38 mumol/min/g dry weight), when compared with normal control (7.52 +/- 0.41 mumol/min/g dry weight; P < 0.05). The enzymatic activity was significantly preserved by histidine (25 mM)--a 1O2 scavenger (7.04 +/- 0.61 mumol/min/g dry weight; P < 0.05 v rose bengal group). After ischemia, the activity of ecto-5'-nucleotidase was greatly reduced (2.51 +/- 0.25 mumol/min/g dry weight), when compared with normal control. Histidine significantly enhanced ecto-5'-nucleotidase activity (6.55 +/- 0.52 mumol/min/g dry weight, P < 0.05 v ischemic control). Adenosine release was consistent with ecto-5'-nucleotidase activity. The time course studies of effects of 1O2 on coronary flow, cardiac function, and LDH release revealed that the damage by 1O2 to ecto-5'-nucleotidase activity and adenosine release primarily accounted for impaired coronary flow, cardiac dysfunction, and impaired cardiac metabolism. Lipid peroxidation induced by exogenous 1O2 or ischemia was in parallel with ecto-5'-nucleotidase deactivation by 1O2. It is concluded that 1O2 causes inactivation of ecto-5'-nucleotidase and attenuation of adenosine release which could possibly be one of the important mechanisms of oxygen radical-mediated myocardial injury.
Zhai
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Department of Pathology, University of Cincinnati Medical Center, Ohio 45267, USA.
Zhou
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Ashraf
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D015720:5'-Nucleotidase / Q000378:metabolism*; D000241:Adenosine / Q000378:metabolism; D000818:Animals; D003326:Coronary Circulation; D006639:Histidine / Q000494:pharmacology; D066298:In Vitro Techniques; D007511:Ischemia / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D015227:Lipid Peroxidation; D008297:Male; D008954:Models, Biological; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012395:Rose Bengal / Q000494:pharmacology / Q000528:radiation effects; D026082:Singlet Oxygen; D016276:Ventricular Function
D026082:Singlet Oxygen; D012395:Rose Bengal; D006639:Histidine; D007770:L-Lactate Dehydrogenase; D015720:5'-Nucleotidase; D000241:Adenosine; D010100:Oxygen