On the nature of the stimulation by glucagon on citrulline synthesis in rat‐liver mitochondria

Verhoeven, Arthur J.; Hensgens, Hubertus E. S. J.; Meijer, Alfred J.; Tager, J. M.

doi:10.1016/0014-5793(82)80911-3

Cited by 18 publications

(7 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is therefore noteworthy that Siess (1983a,b) used EDTA (1.OmM) in his isolation medium, and it is known that EDTA can cause mitochondrial swelling (see Joseph et al, 1980, for discussion). Verhoeven et al (1982) used neither EDTA nor EGTA in their isolation medium, and a Ca2+-induced leakage of mannitol into the matrix could explain their inability to detect changes in respiratory-chain activity. Citrulline synthesis is less sensitive than the other parameters to volume changes (Armston et al, 1982;Siess, 1983a;Jensen et al, 1983) and still demonstrates a glucagen effect in swollen mitochondria (Armston et al, 1982).…”

Section: Discussionmentioning

confidence: 99%

“…Citrulline synthesis is less sensitive than the other parameters to volume changes (Armston et al, 1982;Siess, 1983a;Jensen et al, 1983) and still demonstrates a glucagen effect in swollen mitochondria (Armston et al, 1982). This may explain why Verhoeven et al (1982) were still able to detect a hormone effect on citrulline synthesis when mitochondria were prepared in mannitol medium. Both Jensen et al (1983) and ourselves used EGTA in the mitochondria isolation medium, and were able to detect glucagon effects on all parameters with both media.…”

Section: Discussionmentioning

confidence: 99%

“…Siess and co-workers have suggested that all effects of glucagon treatment of the rat which persist on isolation of the liver mitochondria may be artefacts produced by the use of sucrose media for the preparation of the mitochondria, and are not seen when mitochondria are prepared in mannitol media (Siess et al, 1981;Siess, 1983a,b). This view has been challenged by others (Verhoeven et al, 1982;Jensen et al, 1983), who find enhanced rates of citrulline synthesis in mito-chondria prepared in both media. Jensen et al (1983) were also able to demonstrate significant activation of the respiratory chain by glucagon when mitochondria were prepared in mannitol medium.…”

mentioning

confidence: 97%

“…Jensen et al (1983) were also able to demonstrate significant activation of the respiratory chain by glucagon when mitochondria were prepared in mannitol medium. This was not observed by Siess et al (1981) or Verhoeven et al (1982. An effect of glucagon treatment of rats or isolated hepatocytes on mitochondrial behaviour in crude homogenates (Jensen et al, 1983) or permeabilized cells (Allan et al, 1983) has also been used to indicate that hormone effects are not artefacts of mitochondrial preparation.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Rat liver mitochondria prepared in mannitol media demonstrate increased mitochondrial volumes compared with mitochondria prepared in sucrose media. Relationship to the effect of glucagon on mitochondrial function

Whipps¹,

Halestrap²

1984

Biochemical Journal

View full text Add to dashboard Cite

Liver mitochondria isolated from glucagon-treated rats by using both mannitol- and sucrose-based media showed enhanced uncoupled succinate oxidation, pyruvate metabolism and citrulline synthesis. Mitochondria prepared in mannitol medium showed some stimulation of these parameters compared with those prepared in sucrose medium. This was accompanied by an increase in matrix volume of about 20%. Some [14C]mannitol became permanently associated with mitochondria during preparation. It is suggested that mannitol may enter mitochondria during their preparation and cause swelling. The presence of 4mM-phosphate in the sucrose isolation medium stimulated the same parameters as did glucagon treatment, and also caused an increase in matrix volume of about 20%. These results confirm the conclusion that the mitochondrial volume may be important in the regulation of mitochondrial metabolism. They contradict the conclusion of others [Siess (1983) Hoppe-Seyler's Z. Physiol. Chem. 364, 279-290, 835-838] that mannitol rather than sucrose should be used when studying hormonal effects on mitochondrial metabolism. Reasons for the discrepancies in the results between groups studying the effects of hormones on mitochondrial metabolism are discussed.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 97%

mentioning

confidence: 99%

See 2 more Smart Citations

Rat liver mitochondria prepared in mannitol media demonstrate increased mitochondrial volumes compared with mitochondria prepared in sucrose media. Relationship to the effect of glucagon on mitochondrial function

Whipps¹,

Halestrap²

1984

Biochemical Journal

View full text Add to dashboard Cite

show abstract

“…increases in ApH or AY Shears et al, 1985), or increases in respiration rate with duroquinol as substrate (LaNoue et al, 1984). However, evidence has been presented that at least some of the effects are not artefacts of mitochondria1 isolation (Verhoeven et al, 1982;Jensen et al, 1983;Allan, Chisholm & Titheradge, 1983;Whipps & Halestrap, 1984).…”

Section: (B) Effects In Isolated Liver Mitochondriamentioning

confidence: 99%

Control of Electron Flux Through the Respiratory Chain in Mitochondria and Cells

1987

View full text Add to dashboard Cite

Summary To answer the question ‘What controls the rate of respiration?’ requires a clear definition of control and an explicit description of the limits of the system to be considered. In this review we use a neutral definition of control in which A controls B if changes in A cause changes in B. A useful system to define when discussing the control of respiration consists of the electron transport chain, the H+‐ATPase, the adenine nucleotide carrier, the intramitochondrial adenine nucleotide and phosphate pools, δp and the proton leak across the mitochondrial inner membrane. Controls operating within this system are designated internal controls and many of them are fairly well characterized. Several models have been advanced to describe the rates of these internal processes in isolated mitochondria, including control of respiration rate by cytochrome oxidase with all other steps near to equilibrium, control by the adenine nucleotide carrier or control by the extent of displacement of individual reactions from equilibrium. More recently, analysis using control theory has shown that in the resting state (state 4) most control over flux is exerted by the leak of protons through the inner membrane, whereas in more active, phosphorylating states (up to state 3) control is distributed between a number of steps, including the proton leak, the adenine nucleotide carrier and cytochrome oxidase. This approach seems a very useful framework within which to pose further questions. This system may be treated as a ‘black box’ interacting with its environment (the rest of the mitochondrion and the experimental cuvette or living cell) through the redox states of NAD, Q and O2 and through the phosphorylation state of the extramitochondrial adenine nucleotides. Very few external effectors cross the system boundary; the only well‐characterized ones are long‐chain fatty acyl‐CoA, which inhibits the adenine nucleotide carrier, and fatty acids, which activate a specific uncoupling protein found only in the inner membrane of mitochondria from brown adipose tissue. At this level respiration rate is determined only by the internal properties of the ‘black box’, by the redox states of NAD, Q and O2, and by the phosphorylation status of the extramitochondrial adenine nucleotide pool. Within a cell the rate of respiration is controlled primarily by the rates of reactions feeding electrons to the electron transport chain (through their effects on NADH/NAD and QH2/Q ratios) and by the rates of reactions consuming or producing ATP (through the cytosolic phosphorylation potential or ATP/ADP ratio). Control of reducing equivalent supply occurs through availability of oxidizable substrates (determined by diet and hormonal status), through regulation of pathways such as glycolysis or fatty acid catabolism and, importantly, through Ca2+ activation of intramitochondrial dehydrogenases. Hormonal control over respiration can occur at all the levels mentioned. Hormones may alter the kinetic properties of the oxidative phosphorylation system by alterin...

show abstract

Stimulation of the electron transport chain in mitochondria isolated from rats treated with mannoheptulose or glucagon

Brand

D'Alessandri

Reis

et al. 1990

Archives of Biochemistry and Biophysics

View full text Add to dashboard Cite

On the nature of the stimulation by glucagon on citrulline synthesis in rat‐liver mitochondria

Cited by 18 publications

References 13 publications

Rat liver mitochondria prepared in mannitol media demonstrate increased mitochondrial volumes compared with mitochondria prepared in sucrose media. Relationship to the effect of glucagon on mitochondrial function

Rat liver mitochondria prepared in mannitol media demonstrate increased mitochondrial volumes compared with mitochondria prepared in sucrose media. Relationship to the effect of glucagon on mitochondrial function

Control of Electron Flux Through the Respiratory Chain in Mitochondria and Cells

Stimulation of the electron transport chain in mitochondria isolated from rats treated with mannoheptulose or glucagon

Contact Info

Product

Resources

About