LACTATE OXIDATION COUPLED TO ENERGY-PRODUCTION IN MITOCHONDRIA LIKE PARTICLES FROM SETARIA-DIGITATA, A FILARIAL PARASITE

In the filarial parasite, Setaria digitata, the mitochondria like part icles (MLP) show NAD reduction with sodium lactate. The MLP also reduc es dye and ferricyanide with lactate. The ferricyanide reduction by la ctate is found to be. sensitive to the cytochrome o inhibitor orthohyd roxy diphenyl (OHD) and complex I inhibitor rotenone, modulated by ADP (+) and ATP (-) and inhibited by pyruvate and oxaloacetate. MLP shows lactate oxidation sensitive to OHD, rotenone and sodium malonate. Thu s, the lactate utilizing complex system, consisting of an NADH generat ing MLP bound lactate dehydrogenase and a lactate flavocytochrome redu ctase tightly linked to complex I and cytochrome o, produces ATP in fu nctional association with fumarate reductase complex and other enzyme systems. Hence, this study provides new dimensions to the study of met abolism in filarial parasites. (C) 1994 Academic Press, Inc.