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Title: Measurement of angiotensin converting enzyme induction and inhibition using quantitative in vitro autoradiography: tissue selective induction after chronic lisinopril treatment.
Austin Authors: Kohzuki, M;Johnston, Colin I;Chai, Syn Y;Jackson, B ;Perich, R;Paxton, D;Mendelsohn, Frederick AO
Affiliation: Medicine (University of Melbourne)
Issue Date: 1-Jul-1991
Publication information: Journal of Hypertension 1991; 9(7): 579-87
Abstract: Angiotensin converting enzyme (ACE) inhibitors lead to induction of ACE in animals and humans. This complicates the use of ACE enzymatic activity as an index of inhibition in plasma or tissues after chronic administration of ACE inhibitors. We have, therefore, developed a method for ACE measurement by in vitro autoradiography using an 125I-labelled inhibitor to quantitate total ACE and the concentration of free (not inhibited) ACE in tissues after prolonged administration of ACE inhibitors to rats. Measurements made on unprocessed tissue sections reflect residual free ACE activity in the presence of the unlabelled inhibitor. In a parallel series of adjacent sections, the ACE inhibitor is dissociated from the enzyme by reversibly denaturing the enzyme by zinc chelation. This is followed by reconstitution of the active enzyme by zinc ion replacement and measuring total enzyme concentration. This technique permits measurement of the extent of ACE inhibition and induction. This method was evaluated in tissues of rats following chronic oral administration of lisinopril (10 mg/kg per day) for 2 weeks. The pattern of ACE inhibition was similar to that seen in our previous acute studies. However, induction of ACE was found to be organ specific; plasma total ACE increased 1.75-fold and total ACE in the lung increased by 30% compared with untreated animals, but there was no demonstrable change in total ACE concentration in the kidney, adrenal or aorta. Despite this, during chronic treatment with lisinopril, ACE activity in all of these organs was inhibited with low levels of free ACE.(ABSTRACT TRUNCATED AT 250 WORDS)
Journal: Journal of Hypertension
Type: Journal Article
Subjects: Adrenal Glands.drug effects.enzymology
Angiotensin I.blood
Angiotensin II.blood
Angiotensin-Converting Enzyme Inhibitors.therapeutic use
Aorta.drug effects.enzymology
Edetic Acid.pharmacology
Enalapril.analogs & derivatives.therapeutic use
Enzyme Induction.drug effects
Kidney.drug effects.enzymology
Lung.drug effects.enzymology
Peptidyl-Dipeptidase A.biosynthesis
Rats, Inbred Strains
Testis.drug effects.enzymology
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