MYOCARDIAL FLAVIN REDUCTASE AND RIBOFLAVIN - A POTENTIAL ROLE IN DECREASING REOXYGENATION INJURY

Ferrylmyoglobin has been implicated in cardiac reoxygenation damage. F lavin reductase, an enzyme previously isolated from erythrocytes, can reduce ferrylmyoglobin in the presence of sufficient flavin concentrat ions. Flavin reductase mRNA signals were detected in rabbit heart, lun g, liver, kidney, and isolated cardiomyocytes. It was hypothesized tha t increasing flavin reductase catalysis by administering flavins exoge nously could decrease cardiac reoxygenation damage in isolated rabbit hearts. Riboflavin (150 mu M) inhibited reoxygenation-induced lactate dehydrogenase release by 57%, an effect prevented by hematoporphyrin, a flavin reductase inhibitor. The results suggest that riboflavin supp lementation has cardioprotective effects during reoxygenation and that these effects are mediated by flavin reductase. (C) 1995 Academic Pre ss, Inc.