Biomaterial Database

In vivo measurements of pulmonary angiotensin-converting enzyme kinetics. I. Theory and error analysis. 1995

J Markham, and T J McCarthy, and M J Welch, and D P Schuster

Institute for Biomedical Computing, Washington University Medical School, St. Louis, Missouri 63110, USA.

We developed a procedure for measuring pulmonary angiotensin-converting enzyme kinetics with fluorine-18 fluorocaptopril and positron emission tomography (PET). The method is based on the application of a compartmental receptor model that represents the kinetics of two species of ligand, presumably the trans and cis conformers of captopril. The input function was characterized and includes corrections for the labeled metabolites of fluorocaptopril. Application of the procedure to lung time-activity data obtained with PET produced estimates of kinetic parameters demonstrating fast kinetics for one conformer and slower kinetics for the other. Simulation studies were performed to evaluate the sensitivity of the estimated parameters to errors in the model assumptions and in measured values for variables required for analysis of the PET data. Estimates for two of the kinetic parameters, the amount of perfused unbound functional enzyme normalized to regional lung volume and the association rate constant for the trans conformer, were relatively stable even with large errors in the input data, varying < 30% from true values for all perturbations. Thus, the procedure produces reliable estimates of the kinetics of the trans conformer of captopril as well as theoretical curves that are close to the observed data.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007703	Peptidyl-Dipeptidase A	A peptidyl-dipeptidase that catalyzes the release of a C-terminal dipeptide, oligopeptide-\|-Xaa-Yaa, when Xaa is not Pro, and Yaa is neither Asp nor Glu. Thus, conversion of ANGIOTENSIN I to ANGIOTENSIN II, with increase in vasoconstrictor activity, but no action on angiotensin II. It is also able to inactivate BRADYKININ, a potent vasodilator; and has a glycosidase activity which releases GPI-anchored proteins from the membrane by cleaving the mannose linkage in the GPI moiety. (From https://www.uniprot.org April 15, 2020).	ACE1 Angiotensin-Converting Enzyme 1,ACE1 Protein,Angiotensin Converting Enzyme,Angiotensin Converting Enzyme 1,Antigens, CD143,CD143 Antigens,Dipeptidyl Carboxypeptidase I,Kininase II,Peptidase P,Angiotensin I-Converting Enzyme,Carboxycathepsin,Dipeptidyl Peptidase A,Kininase A,ACE1 Angiotensin Converting Enzyme 1,Angiotensin I Converting Enzyme,Carboxypeptidase I, Dipeptidyl,Peptidyl Dipeptidase A
D008168	Lung	Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.	Lungs
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D002216	Captopril	A potent and specific inhibitor of PEPTIDYL-DIPEPTIDASE A. It blocks the conversion of ANGIOTENSIN I to ANGIOTENSIN II, a vasoconstrictor and important regulator of arterial blood pressure. Captopril acts to suppress the RENIN-ANGIOTENSIN SYSTEM and inhibits pressure responses to exogenous angiotensin.	(S)-1-(3-Mercapto-2-methyl-1-oxopropyl)-L-proline,Capoten,Lopirin,SQ-14,225,SQ-14,534,SQ-14225,SQ-14534,SQ 14,225,SQ 14,534,SQ 14225,SQ 14534,SQ14,225,SQ14,534,SQ14225,SQ14534
D003198	Computer Simulation	Computer-based representation of physical systems and phenomena such as chemical processes.	Computational Modeling,Computational Modelling,Computer Models,In silico Modeling,In silico Models,In silico Simulation,Models, Computer,Computerized Models,Computer Model,Computer Simulations,Computerized Model,In silico Model,Model, Computer,Model, Computerized,Model, In silico,Modeling, Computational,Modeling, In silico,Modelling, Computational,Simulation, Computer,Simulation, In silico,Simulations, Computer
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D005462	Fluorine Radioisotopes	Unstable isotopes of fluorine that decay or disintegrate emitting radiation. F atoms with atomic weights 17, 18, and 20-22 are radioactive fluorine isotopes.	Radioisotopes, Fluorine
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014055	Tomography, Emission-Computed	Tomography using radioactive emissions from injected RADIONUCLIDES and computer ALGORITHMS to reconstruct an image.	CAT Scan, Radionuclide,CT Scan, Radionuclide,Computerized Emission Tomography,Radionuclide Tomography, Computed,Scintigraphy, Computed Tomographic,Tomography, Radionuclide-Computed,Computed Tomographic Scintigraphy,Emission-Computed Tomography,Radionuclide Computer-Assisted Tomography,Radionuclide Computerized Tomography,Radionuclide-Computed Tomography,Radionuclide-Emission Computed Tomography,Tomography, Computerized Emission,CAT Scans, Radionuclide,CT Scans, Radionuclide,Computed Radionuclide Tomography,Computed Tomography, Radionuclide-Emission,Computer-Assisted Tomographies, Radionuclide,Computer-Assisted Tomography, Radionuclide,Computerized Tomography, Radionuclide,Emission Computed Tomography,Emission Tomography, Computerized,Radionuclide CAT Scan,Radionuclide CAT Scans,Radionuclide CT Scan,Radionuclide CT Scans,Radionuclide Computed Tomography,Radionuclide Computer Assisted Tomography,Radionuclide Computer-Assisted Tomographies,Radionuclide Emission Computed Tomography,Scan, Radionuclide CAT,Scan, Radionuclide CT,Scans, Radionuclide CAT,Scans, Radionuclide CT,Tomographic Scintigraphy, Computed,Tomographies, Radionuclide Computer-Assisted,Tomography, Computed Radionuclide,Tomography, Emission Computed,Tomography, Radionuclide Computed,Tomography, Radionuclide Computer-Assisted,Tomography, Radionuclide Computerized,Tomography, Radionuclide-Emission Computed