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 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.

Accumulation of D-arginine by rat liver mitochondria

1987 ◽  
Vol 65 (12) ◽  
pp. 1057-1063 ◽  
Author(s):  
Rafael Villalobos-Molina ◽  
J. Pablo Pardo ◽  
Alfredo Saavedra-Molina ◽  
Enrique Piña
Keyword(s):  
Membrane Potential ◽  
Rat Liver ◽  
Mitochondrial Respiration ◽  
Mitochondrial Membrane ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Osmotic Swelling ◽  
Dose Dependent Fashion ◽  
Dose Dependent

The permeability of the inner mitochondrial membrane from rat liver to D-arginine was studied. By using safranin as a probe of the membrane potential, depolarization of energized liver mitochondria occurred in a dose-dependent fashion starting at 3.3 mmol/L of D- or DL-arginine. When ethidium bromide fluorescence was employed, a decrease in the membrane potential due to D- or DL-arginine was observed. A parallel significant change in succinate-induced respiration in rat liver mitochondria was found in response to osmotic swelling in 125 mmol/L of D-arginine salts. L-Arginine, L-glutamine, L-asparagine, L-ornithine, D-ornithine, and L-lysine did not modify the membrane potential at the concentrations tested. D-Arginine was not transformed into citrulline, but 1.0 mmol/L of the D-amino acid inhibited, by 42%, the state 3 of mitochondrial respiration using succinate as substrate. When D-arginine was used in combination with nigericin, a 40% inhibition of mitochondrial respiration in state 3 was recorded with succinate and with glutamate–malate as substrates.

scholarly journals The Swelling of Rat Liver Mitochondria by Thyroxine and its Reversal

1959 ◽  
Vol 5 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Albert L. Lehninger ◽  
Betty Lou Ray ◽  
Marion Schneider
Keyword(s):  
Oxidative Phosphorylation ◽  
Temperature Coefficient ◽  
Oxidation State ◽  
Respiratory Chain ◽  
Rat Liver ◽  
Mitochondrial Membrane ◽  
Ph Dependence ◽  
Liver Mitochondria ◽  
The Other ◽  
Rat Liver Mitochondria

The in vitro swelling action of L-thyroxine on rat liver mitochondria as examined photometrically represents an acceleration of a process which the mitochondria are already inherently capable of undergoing spontaneously, as indicated by the identical kinetic characteristics and the extent of thyroxine-induced and spontaneous swelling, the nearly identical pH dependence, and the fact that sucrose has a specific inhibitory action on both types of swelling. However, thyroxine does not appear to be a "catalyst" or coenzyme since it does not decrease the temperature coefficient of spontaneous swelling. The temperature coefficient is very high, approximately 6.0 near 20°. Aging of mitochondria at 0° causes loss of thyroxine sensitivity which correlates closely with the loss of bound DPN from the mitochondria, but not with loss of activity of the respiratory chain or with the efficiency of oxidative phosphorylation. Tests with various respiratory chain inhibitors showed that the oxidation state of bound DPN may be a major determinant of thyroxine sensitivity; the oxidation state of the other respiratory carriers does not appear to influence sensitivity to thyroxine. These facts and other considerations suggest that a bound form of mitochondrial DPN is the "target" of the action of thyroxine. The thyroxine-induced swelling is not reversed by increasing the osmolar concentration of external sucrose, but can be "passively" or osmotically reversed by adding the high-particle weight solute polyvinylpyrrolidone. The mitochondrial membrane becomes more permeable to sucrose during the swelling reaction. On the other hand, thyroxine-induced swelling can be "actively" reversed by ATP in a medium of 0.15 M KCl or NaCl but not in a 0.30 M sucrose medium. The action of ATP is specific; ADP, Mn++, and ethylenediaminetetraacetate are not active. It is concluded that sucrose is an inhibitor of the enzymatic relationship between oxidative phosphorylation and the contractility and permeability properties of the mitochondrial membrane. Occurrence of different types of mitochondrial swelling, the intracellular factors affecting the swelling and shrinking of mitochondria, as well as the physiological significance of thyroxine-induced swelling are discussed.

scholarly journals A permeability barrier in mitochondria in ‘high-energy states’ against positively charged disulphides

1968 ◽  
Vol 107 (5) ◽  
pp. 645-654 ◽  
Author(s):  
S. Skrede
Keyword(s):  
Oxidative Phosphorylation ◽  
Energy State ◽  
Respiratory Control ◽  
Liver Mitochondria ◽  
High Energy ◽  
Rat Liver Mitochondria ◽  
Permeability Barrier ◽  
Inner Mitochondrial Membrane ◽  
Energy States ◽  
State 1

1. In rat liver mitochondria in state 1 or 4 there is a permeability barrier against cystamine, probably in the inner membrane. 2. The permeability barrier was broken (a) when oxidative phosphorylation was uncoupled, (b) when the respiratory chain was inhibited or in anaerobiosis, or (c) when phosphate was added in the absence of exogenous substrate. Under these conditions increased amounts of [35S]cystamine residues were bound to matrix proteins. 3. It appears that the permeability barrier against cystamine in mitochondria reflects a ‘high-energy state’. A gradual increase in the permeability for cystamine strikingly coincided with the loss of respiratory control induced by increasing concentrations of different uncoupling agents. 4. Cystamine caused uncoupling of oxidative phosphorylation in state 2 or 5, but not in state 1, 3 or 4. The uncoupling effect of cystamine was dependent on the phosphorylation potential. ATP counteracted, whereas ADP potentiated, the uncoupling by cystamine. 5. The variable penetration of cystamine appears to depend on its positive charge, since a dication derivative, NNN′N′-tetramethylcystamine, has a similar pattern of penetration, whereas an uncharged derivative, NN′-diacetylcystamine, penetrates rapidly into mitochondria irrespective of their metabolic state. 6. It is suggested that a charge barrier is present in or across the inner mitochondrial membrane in ‘high-energy states’.

scholarly journals Calcium ion cycling in rat liver mitochondria

1978 ◽  
Vol 174 (2) ◽  
pp. 613-620 ◽  
Author(s):  
Chidambaram Ramachandran ◽  
Fyfe L. Bygrave
Keyword(s):  
Rat Liver ◽  
Calcium Ion ◽  
Mitochondrial Membrane ◽  
Initial Rate ◽  
Liver Mitochondria ◽  
Ruthenium Red ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Subsequent Addition ◽  
Unique Mechanism

1. Addition of N-ethylmaleimide to rat liver mitochondria respiring with succinate as substrate decreases both the initial rate of Ca2+ transport and the ability of mitochondria to retain Ca2+. As a result, Ca2+ begins to leave the mitochondria soon after it has entered. Half-maximal effects occur at an N-ethylmaleimide concentration of about 100nmol/mg of protein. 2. The efflux of Ca2+ induced by N-ethylmaleimide is not prevented by Mg2+ or by Ruthenium Red at concentrations known to prevent Ca2+ efflux when exogenous phosphate also is present. Swelling of mitochondria does not accompany N-ethylmaleimide-induced Ca2+ efflux. 3. Addition of Ca2+ to rat liver mitochondria in the presence of N-ethylmaleimide produces an immediate decrease in ΔE (membrane potential), which decreases further to only a slight extent over the next 8min. Concomitant with this is an immediate increase and then levelling off of the −59ΔpH (transmembrane pH gradient). 4. Preincubation of rat liver mitochondria with p-chloromercuribenzenesulphonate, which by contrast with N-ethylmaleimide is unable to penetrate the inner mitochondrial membrane, also prevents Ca2+ retention. The ΔE and −59ΔpH respond to Ca2+ addition in a manner similar to that which occurs when N-ethylmaleimide is present. Subsequent addition of mercaptoethanol produces an immediate increase in both ΔE and −59ΔpH. At the same time Ca2+ is rapidly accumulated by the organelles. 5. The above data are interpreted as indicating that under the conditions of Ca2+ efflux seen here, the mitochondria retain their functional integrity. This contrasts with the uncoupling effect of Ca2+ seen in the presence of Pi, which generally leads to a loss of mitochondrial integrity. We suggest that a unique mechanism of Ca2+ cycling is able to take place when mitochondria have been treated with N-ethylmaleimide.

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