The rabbit pulmonary monooxygenase system: Characteristics and activities of two forms of pulmonary cytochrome P-450

Wolf, Charles; Szutowski, Mirosław; Ball, Louise M.; Philpot, Richard M.

doi:10.1016/0009-2797(78)90066-2

Cited by 69 publications

(16 citation statements)

References 22 publications

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“…The best understood pulmonary P-450 system is that of the rabbit. Cytochrome P-450 isozymes, forms 2 and 5,* make up greater than 70% of the rabbit pulmonary cytochrome P-450 (11). In contrast, these isozymes are minor components of the hepatic system except in rabbits that have been treated with phenobarbital, an inducer that has little or no effect on the pulmonary P-450 system.…”

Section: Rabbit Pulmonary Cytochrome P-450 Monooxygenase Systemmentioning

confidence: 99%

“…The identity of the pulmonary isozymes as forms 2 and 5 has been established by direct comparison with the hepatic enzymes. No structural (molecular weights, amino acid compositions, N-and C-terminal sequences, peptide maps), immunochemical (Ouchterlony immunodiffusion, Western blotting, inhibition of activity), or catalytic (substrate specificities in purified and microsomal systems) differences between the sets of isozymes from liver and lung have been detected (11)(12)(13)(14)(15)(16). Whether the microheterogeneous populations of these isozymes from liver and lung are identical remains to be resolved.…”

Section: Rabbit Pulmonary Cytochrome P-450 Monooxygenase Systemmentioning

confidence: 99%

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Role of cytochrome P-450 and related enzymes in the pulmonary metabolism of xenobiotics.

Philpot¹,

Smith²

1984

Environ Health Perspect

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The lung metabolizes a wide variety of xenobiotics and, in the process, forms products that may be more or less toxic than the parent compound. The consequence of metabolism, activation or detoxication, is a function of the nature of the substrate and of the characteristics and concentrations of the enzymes involved. As a result, the biotransformation of xenobiotics can lead to their excretion or to the formation of reactive products that produce deleterious effects by binding covalently to tissue macromolecules. Among the enzymes that metabolize xenobiotics, those associated with the cytochrome P-450-dependent monooxygenase system are probably the most important. The route by which a given substrate is metabolized in a tissue or cell is, to a great extent, determined by the types and concentrations of cytochrome P-450 isozymes present. We are just beginning to understand the distribution of these enzymes in lung and to appreciate the species and cellular differences that exist.

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Section: Rabbit Pulmonary Cytochrome P-450 Monooxygenase Systemmentioning

confidence: 99%

Section: Rabbit Pulmonary Cytochrome P-450 Monooxygenase Systemmentioning

confidence: 99%

Role of cytochrome P-450 and related enzymes in the pulmonary metabolism of xenobiotics.

Philpot¹,

Smith²

1984

Environ Health Perspect

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“…Pulmonary cytochromes P-450| and P-450n have been isolated from untreated rabbits [1]. The two hemoproteins are differ ent in physical, catalytic, and immunochemi cal properties [1,4]. In a reconstituted sys tem, the pulmonary cytochromes are able to metabolize drugs and other foreign com pounds, such as benzo(a)pyrene [1,5].…”

Section: Introductionmentioning

confidence: 99%

“…Pulmonary cytochromes P-450| and P-450n have been isolated from untreated rabbits [1]. The two hemoproteins are differ ent in physical, catalytic, and immunochemi cal properties [1,4].…”

Section: Introductionmentioning

confidence: 99%

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Pulmonary Cytochromes P-450 from Rabbits Treated with Phenobarbital

Ueng¹,

Alvares²

1985

Pharmacology

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Pretreatment of rabbits with phenobarbital caused significant increases in total pulmonary cytochrome P-450 content, benzo(a)pyrene hydroxylase and 7-ethoxycoumarin O-deethylase activities and to a lesser extent in benzphetamine N-demethylase activity in lung microsomes. However, 7-ethoxyresorufin O-deethylase activity was not significantly altered. In addition, the pulmonary concentration of the cytochrome P-450-metyrapone complex was increased significantly. Column chromatography of the pulmonary monooxygenases demonstrated that in untreated and phenobarbital-treated rabbits, cytochromes P-450_I and P-450_II constituted the major forms of cytochrome P-450 isozymes. In addition, the chromatographic studies showed that pretreatment with phenobarbital caused an increase in the content of cytochrome P-450_I, but not of cytochrome P-450_II. These observations were confirmed by subjecting the pulmonary cytochromes to gel electrophoresis, and staining of the gels for protein and heme.

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Chromatographic and catalytic properties of multiple forms of rabbit pulmonary cytochromes P‐450

Ueng

Peiperl

Alvares

1988

J. Biochem. Toxicol.

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Rabbit pulmonary cytochrome P-450 forms 2, 5, and 6 were resolved using anion-exchange high-performance liquid chromatography (HPLC) and their properties compared with rabbit liver cytochrome P-450 isozymes LM2 and LM6. Although rabbit pulmonary form 2 and liver LM2 had similar electrophoretic mobilities and similar substrate specificities in reconstitution experiments, they differed in their HPLC elution profiles. High-performance liquid chromatography of pulmonary microsomes from rabbits treated with 3-methylcholanthrene (3-MC) revealed the induction of form 6 isozyme, which had a retention time, electrophoretic mobility, and substrate specificity similar to those of rabbit liver LM6. In reconstitution experiments, forms 2 and 6 showed the highest substrate specificities toward benzphetamine and 7-ethoxyresorufin, respectively. Rabbit lung cytochrome P-450 form 5 was relatively inactive toward all substrates tested.

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The rabbit pulmonary monooxygenase system: Characteristics and activities of two forms of pulmonary cytochrome P-450

Cited by 69 publications

References 22 publications

Role of cytochrome P-450 and related enzymes in the pulmonary metabolism of xenobiotics.

Role of cytochrome P-450 and related enzymes in the pulmonary metabolism of xenobiotics.

Pulmonary Cytochromes P-450 from Rabbits Treated with Phenobarbital

Chromatographic and catalytic properties of multiple forms of rabbit pulmonary cytochromes P‐450

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