Mode of effect of Ostruthin, a phenolic coumarin on respiration and oxidative phosphorylation of rat liver mitochondria

1980 ◽  
Vol 45 (2) ◽  
pp. 653-664 ◽  
Author(s):  
Vladimír Dadák ◽  
Petr Zbořil ◽  
Josef Šanek ◽  
Augustin Svoboda
Keyword(s):  
Electron Microscope ◽  
Monoamine Oxidase ◽  
Mitochondrial Membrane ◽  
Respiratory Control ◽  
Liver Mitochondria ◽  
Mitochondrial Proteins ◽  
Phosphorus Compounds ◽  
Rat Liver Mitochondria ◽  
Outer Mitochondrial Membrane ◽  
Freeze Etching

Ostruthin (6-genaryl-7-hydroxycoumarin) in concentration of 5-30 nmol/mg protein behaves as an uncoupler. It eliminates the respiratory control in liver mitochondria, decreases the ratioof ADP/O uptake, and stimulates ATPase activity. It also acts as an inhibitor of the exchange reaction between 32Pi and ATP. Higher concentrations induce the swelling of mitochondria, bring about changes in the permeability of the membrane, and significantly alter the ultrastructure of mitochondria. A considerable quantity of mitochondrial proteins and a part of the phosphorus compounds are released into solution during this process. The investigation of the distribution of typical enzymes of membranes and matrix (monoamine oxidase, cytochrome oxidase, succinate dehydrogenase, and malate dehydrogenase) has shown that the mitochondrial components released come from matrix. Ostruthin concentrations higher than 50 nmol/mg protein cause fragmentation of membranes observable in ultrathin slices in the electron microscope. Fragmentation of both the inner and the outer mitochondrial membrane was demonstrated by the method of freeze etching.

scholarly journals The maturation of the inner membrane of foetal rat liver mitochondria. An example of a positive-feedback mechanism

1975 ◽  
Vol 150 (3) ◽  
pp. 477-488 ◽  
Author(s):  
J K Pollak
Keyword(s):  
Oxidative Phosphorylation ◽  
Rat Liver ◽  
Mitochondrial Membrane ◽  
Respiratory Control ◽  
Liver Mitochondria ◽  
Neonatal Rat ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Mature Adult ◽  
Foetal Rat

A new method was devised for the isolation of foetal and neonatal rat lvier mitochondria, giving higher yields than conventional methods. 2. During development from the perinatal period to the mature adult, the ratio of cytochrome oxidase/succinate-cytochrome c reductase changes. 3. The inner mitochondrial membrane of foetal liver mitochondria possesses virtually no osmotic activity; the permeability to sucrose decreases with increasing developmental age. 4. Foetal rat liver mitochondria possess only marginal respiratory control and do not maintain Ca2+-induced respiration; they also swell in respiratory-control medium in the absence of substrate. ATP enhances respiratory control and prevents swelling, adenylyl imidodiphosphate, ATP+atractyloside enhance the R.C.I. (respiratory control index), Ca2+-induced respiratory control and prevent swelling, whereas GTP and low concentrations of ADP have none of these actions. It is concluded that the effect of ATP depends on steric interaction with the inner mitochondrial membrane. 5. When 1-day pre-partum foetuses are obtained by Caesarean section and maintained in a Humidicrib for 90 min, mitochondrial maturation is ‘triggered’, so that their R.C.I. is enhanced and no ATP is required to support Ca2+-dependent respiratory control or to inhibit mitochondrial swelling. 6. It is concluded that foetal rat liver mitochondria in utero do not respire, although they are capable of oxidative phosphorylation in spite of their low R.C.I. The different environmental conditions which the neonatal rat encounters ex utero enable the hepatic mitochondria to produce ATP, which interacts with the inner mitochondrial membrane to enhance oxidative phosphorylation by an autocatalytic mechanism.

scholarly journals THE SUBMITOCHONDRIAL LOCALIZATION OF MONOAMINE OXIDASE

1967 ◽  
Vol 32 (3) ◽  
pp. 719-735 ◽  
Author(s):  
Carl Schnaitman ◽  
V. Gene Erwin ◽  
John W. Greenawalt
Keyword(s):  
Monoamine Oxidase ◽  
Cytochrome Oxidase ◽  
Oxidase Activity ◽  
Mitochondrial Membrane ◽  
High Speed ◽  
Rat Liver Mitochondria ◽  
Outer Mitochondrial Membrane ◽  
Monoamine Oxidase Activity ◽  
Inner Membrane ◽  
Low Speed

Controlled osmotic lysis (water-washing) of rat liver mitochondria results in a mixed population of small vesicles derived mainly from the outer mitochondrial membrane and of larger bodies containing a few cristae derived from the inner membrane. These elements have been separated on Ficoll and sucrose gradients. The small vesicles were rich in monoamine oxidase, and the large bodies were rich in cytochrome oxidase. Separation of the inner and outer membranes has also been accomplished by treating mitochondria with digitonin in an isotonic medium and fractionating the treated mitochondria by differential centrifugation. Treatment with low digitonin concentrations released monoamine oxidase activity from low speed mitochondrial pellets, and this release of enzymatic activity was correlated with the loss of the outer membrane as seen in the electron microscope. The low speed mitochondrial pellet contained most of the cytochrome oxidase and malate dehydrogenase activities of the intact mitochondria, while the monoamine oxidase activity could be recovered in the form of small vesicles by high speed centrifugation of the low speed supernatant. The results indicate that monoamine oxidase is found only in the outer mitochondrial membrane and that cytochrome oxidase is found only in the inner membrane. Digitonin treatment released more monoamine oxidase than cytochrome oxidase from sonic particles, thus indicating that digitonin preferentially degrades the outer mitochondrial membrane.

scholarly journals THE SURFACE CHARGE OF RAT LIVER MITOCHONDRIA AND THEIR MEMBRANES

1970 ◽  
Vol 46 (1) ◽  
pp. 137-150 ◽  
Author(s):  
Hans-G. Heidrich ◽  
Roland Stahn ◽  
Kurt Hannig
Keyword(s):  
Surface Charge ◽  
Electrophoretic Mobility ◽  
Mitochondrial Membrane ◽  
Krebs Cycle ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Outer Mitochondrial Membrane ◽  
Contraction Procedure ◽  
Matrix Fraction ◽  
Nadh Cytochrome

The surface charge of intact mitochondria and submitochondrial particles was examined by the technique of preparative free flow electrophoresis. When submitochondrial preparations obtained by a swelling-contraction procedure were examined with this technique, two fractions were observed. One of these fractions exhibited the same electrophoretic properties as intact mitochondria, which indicated that it was derived from the outer limiting membrane of the mitochondrion. This fraction was found to contain the enzymes monoamine oxidase and rotenone-insensitive NADH-cytochrome c reductase which have been reported to be localized in the outer mitochondrial membrane. The other fraction exhibited an electrophoretic mobility which was different from that of intact mitochondria, and this fraction contained enzymes characteristic of the inner membrane-matrix fraction such as soluble and particulate enzymes of the Krebs cycle. Microsomes exhibited an electrophoretic mobility which was almost identical with that of the outer mitochondrial membrane. In addition to resolving the localization of enzymes in mitochondrial membranes, these data indicate that the outer limiting membrane of the mitochondrion is the sole determinant of the surface charge of mitochondria.

scholarly journals Uptake of protoporphyrin IX by isolated rat liver mitochondria

1980 ◽  
Vol 188 (2) ◽  
pp. 329-335 ◽  
Author(s):  
M E Koller ◽  
I Romslo
Keyword(s):  
Rat Liver ◽  
Mitochondrial Membrane ◽  
Protoporphyrin Ix ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Erythropoietic Protoporphyria ◽  
Inner Membrane ◽  
Isolated Rat Liver ◽  
Isolated Rat

Rat liver mitochondria accumulate protoporphyrin IX from the suspending medium into the inner membrane in parallel with the magnitude of the transmembrane K+ gradient (K+in/K+out). Only protoporphyrin IX taken up in parallel with the transmembrane K+ gradient is available for haem synthesis. Coproporphyrins (isomers I and III) are not taken up by the mitochondria. The results support the suggestion by Elder & Evans [(1978) Biochem. J. 172, 345-347] that the prophyrin to be taken up by the inner mitochondrial membrane belongs to the protoporphyrin(ogen) IX series. Protoporphyrin IX at concentrations above 15 nmol/mg of protein has detrimental effects on the structural and functional integrity of the mitochondria. The relevance of these effects to the hepatic lesion in erythropoietic protoporphyria is discussed.

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