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The regulation of cardiac heme oxygenase and cytochrome P-450 mixed function oxidase was studied in the rabbit heart. Heme oxygenase activity is found in ventricular and atrial microsomal fractions. This activity is NADPH dependent, and is inhibited by tin and zinc protoporphyrin, but not by either SKF 525A or 7,8-benzoflavone. Immunologic studies of cardiac heme oxygenase demonstrate that antibodies prepared against human purified hepatic heme oxygenase recognize rabbit atrial heme oxygenase and inhibit the enzyme activity by 92%. In contrast, control immunoglobulin does not inhibit heme oxygenase activity. Further, the western blotting technique demonstrates that a similar band of protein with a molecular weight of 32,000 exists in cardiac microsomes and that no protein cross-reacts with purified hepatocyte heme oxygenase. Marked induction of atrial heme oxygenase is observed in microsomal fractions prepared from rabbits treated with cobalt chloride. Atrial microsomes possess 0.24 nmol of cytochrome P-450 as compared to 0.68 nmol/mg protein in microsomes from the liver. The levels of aryl hydrocarbon hydroxylase (AHH) activity, a cytochrome P-450-dependent enzyme, in ventricle and atrium are stimulated by a NADPH-generating system and are sensitive to 7,8-benzoflavone, and SKF 525A, known inhibitors of cytochrome P-450 mixed function oxidase. AHH activity in ventricular and atrial microsomes is 2-3% of that seen in liver microsomes whereas the P-450 content/mg protein is about 20% of that observed in the liver. AHH activity is mediated by a form of cytochrome P-450 that is inducible by 3-methylcholanthrene/beta-naphthoflavone. A possible new role of the heart cytochrome P-450 system in cardiac function is proposed.(ABSTRACT TRUNCATED AT 250 WORDS)
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
September 1976,
Archives of biochemistry and biophysics,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
June 1981,
The Journal of nutrition,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
January 1990,
Methods in enzymology,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
March 1986,
Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
December 1980,
The Journal of biological chemistry,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
September 1987,
Investigative ophthalmology & visual science,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
February 1990,
Bulletin of environmental contamination and toxicology,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
January 1986,
Advances in experimental medicine and biology,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
December 1984,
Archives of biochemistry and biophysics,
N G Abraham, and
A Pinto, and
R D Levere, and
K Mullane
September 1987,
Biochemical pharmacology,
