title: Oxidative properties of carp red and white muscle.
abstract: Substrate preferences of isolated mitochondria and maximal enzyme activities were used to assess the oxidative capacities of red muscle (RM) and white muscle (WM) of carp (Cyprinus carpio). A 14-fold higher activity of citrate synthase (CS) in RM reflects the higher mitochondrial density in this tissue. RM mitochondria oxidize pyruvate and fatty acyl carnitines (8:O, 12:O, 16:O) at similarly high rates. WM mitochondria oxidize these fatty acyl carnitines at 35-70% the rate of pyruvate, depending on chain length. WM has only half the carnitine palmitoyl transferase/CS ratio of RM, but similar ratios of beta-hydroxyacyl CoA dehydrogenase/CS. Ketone bodies are poor substrates for mitochondria from both tissues. In both tissues mitochondrial alpha-glycerophosphate oxidation was minimal, and alpha-glycerophosphate dehydrogenase was present at low activities, suggesting the alpha-glycerophosphate shuttle is of minor significance in maintaining cytosolic redox balance in either tissue. The mitochondrial oxidation rates of other substrates relative to pyruvate are as follows: alpha-ketoglutarate 90% (RM and WM); glutamate 45% (WM) and 70% (RM); proline 20% (WM) and 45% (RM). Oxidation of neutral amino acids (serine, glycine, alanine, beta-alanine) was not consistently detectable. These data suggest that RM and WM differ in mitochondrial properties as well as mitochondrial abundance. Whereas RM mitochondria appear to be able to utilize a wide range of metabolic fuels (fatty acids, pyruvate, amino acids but not ketone bodies), WM mitochondria appear to be specialized to use pyruvate.
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, Canada.
authors.forename: C D
authors.initials: CD
authors.lastname: Moyes
authors.forename: L T
authors.initials: LT
authors.lastname: Buck
authors.forename: P W
authors.initials: PW
authors.lastname: Hochachka
authors.forename: R K
authors.initials: RK
authors.lastname: Suarez
mesh_terms: D000818:Animals; D002347:Carps / Q000378:metabolism*; D003530:Cyprinidae / Q000378:metabolism*; D007700:Kinetics; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000378:metabolism*; D009928:Organ Specificity; D010101:Oxygen Consumption