The effect of phenobarbitone on protein synthesis by liver polyribosomes in fed and starved rats

Ragnotti, Giovanni; Aletti, Maria Giovanna

doi:10.1042/bj1460001

Cited by 13 publications

(2 citation statements)

References 41 publications

(42 reference statements)

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“…It has been suggested that inducers may affect the initiation of protein synthesis and even translation central factors [94]. Phenobarbitone has been reported to increase C 14 -leucine incorporation into proteins by rat liver polyribosomes [95]. The increased RNA and protein synthesis as well as the stabilization and decreased degradation of these components has been implicated in the induction of drug metabolizing activity [96].…”

Section: Inducing Agents and Mechanism Of Inductionmentioning

confidence: 99%

Drug-Metabolizing Enzymes Mechanisms and Functions

Sheweita

2000

CDM

213

128

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Drug-metabolizing enzymes are called mixed-function oxidase or monooxygenase and containing many enzymes including cytochrome P450, cytochrome b5, and NADPH-cytochrome P450 reductase and other components. The hepatic cytochrome P450s (Cyp) are a multigene family of enzymes that play a critical role in the metabolism of many drugs and xenobiotics with each cytochrome isozyme responding differently to exogenous chemicals in terms of its induction and inhibition. For example, Cyp 1A1 is particularly active towards polycyclic aromatic hydrocarbons (PAHs), activating them into reactive intermediates those covalently bind to DNA, a key event in the initiation of carcinogenesis. Likewise, Cyp 1A2 activates a variety of bladder carcinogens, such as aromatic amines and amides. Also, some forms of cytochrome P450 isozymes such as Cyp 3A and 2E1 activate the naturally occurring carcinogens (e.g. aflatoxin B1) and N-nitrosamines respectively into highly mutagenic and carcinogenic agents. The carcinogenic potency of PAHs, and other carcinogens and the extent of binding of their ultimate metabolites to DNA and proteins are correlated with the induction of cytochrome P450 isozymes. Phase II drug-metabolizing enzymes such as glutathione S-transferase, aryl sulfatase and UDP-glucuronyl transferase inactivate chemical carcinogens into less toxic or inactive metabolites. Many drugs change the rate of activation or detoxification of carcinogens by changing the activities of phases I and II drug-metabolizing enzymes. The balance of detoxification and activation reactions depends on the chemical structure of the agents, and is subjected to many variables that are a function of this structure, or genetic background, sex, endocrine status, age, diet, and the presence of other chemicals. It is important to realize that the enzymes involved in carcinogen metabolism are also involved in the metabolism of a variety of substrates, and thus the introduction of specific xenobiotics may change the operating level and the existence of other chemicals. The mechanisms of modification of drug-metabolizing enzyme activities and their role in the activation and detoxification of xenobiotics and carcinogens have been discussed in the text.

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Section: Inducing Agents and Mechanism Of Inductionmentioning

confidence: 99%

Drug-Metabolizing Enzymes Mechanisms and Functions

Sheweita

2000

CDM

213

128

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“…Postmitochondrial supernatant was prepared as described by Blobel & Potter (1967). Incubation and determination of radioactivity incorporated into protein were performed as described by Ragnotti & Aletti (1975), with [3Hlleucine (0.5,uCi/sample).…”

Section: Amino Acid Incorporation By Postmitochondrial Supernatantmentioning

confidence: 99%

Effect of post-ischaemic recovery on albumin synthesis and relative amount of translatable albumin messenger RNA in rat liver

Cairo¹,

Schiaffonati²,

Aletti³

et al. 1982

Biochemical Journal

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In liver cells recovering from reversible ischaemia, total protein synthesis by postmitochondrial supernatant and membrane-bound and free polyribosomes is not different from that in sham-operated controls. However, the relative proportion of specific proteins is changed, since the incorporation of [3H]leucine in vivo into liver albumin, relative to incorporation into total protein, as determined by precipitation of labelled albumin with the specific antibody, decreases by 40-50% in post-ischaemic livers. Cell-free synthesis by membrane-bound polyribosomes and poly(A)-enriched RNA isolated from unfractionated liver homogenate shows that the decrease in albumin synthesis in liver of rats recovering from ischaemia is due to the relative decrease in translatable albumin mRNA.

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Biochemical Aspects

Parke¹

1977

Principles of Surgical Oncology

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The effect of phenobarbitone on protein synthesis by liver polyribosomes in fed and starved rats

Cited by 13 publications

References 41 publications

Drug-Metabolizing Enzymes Mechanisms and Functions

Drug-Metabolizing Enzymes Mechanisms and Functions

Effect of post-ischaemic recovery on albumin synthesis and relative amount of translatable albumin messenger RNA in rat liver

Biochemical Aspects

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