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[3H]Captopril binding to membrane associated angiotensin converting enzyme
Biochemical and Biophysical Research Communications
|May 16, 1983
Summary
This study shows that [3H]Captopril selectively binds to angiotensin converting enzyme in rat tissues. This finding helps understand the enzyme's localization and captopril's pharmacological actions.
Area of Science:
- Pharmacology
- Biochemistry
- Physiology
Background:
- Angiotensin converting enzyme (ACE) plays a crucial role in the renin-angiotensin system.
- Understanding the precise localization and function of ACE is vital for drug development.
- Captopril is a known inhibitor of ACE with therapeutic applications.
Purpose of the Study:
- To investigate the binding characteristics of [3H]Captopril in rat tissues.
- To determine if [3H]Captopril binding is selective for ACE.
- To correlate [3H]Captopril binding with ACE activity and distribution.
Main Methods:
- Radioligand binding assays using [3H]Captopril on rat tissue membrane fractions.
- Enzyme activity assays measuring ACE with hippuryl-L-histidine-L-leucine.
- Competitive inhibition studies with various ACE inhibitors.
Main Results:
- [3H]Captopril exhibited saturable and reversible binding to rat tissue membranes with a KD of 2.4 nM.
- The distribution of [3H]Captopril binding mirrored ACE activity across various tissues and brain regions, notably high in the choroid plexus, lung, and corpus striatum.
- Several ACE inhibitors, including captopril, demonstrated similar potencies in inhibiting both [3H]Captopril binding and ACE activity.
Conclusions:
- The data strongly support the selective binding of [3H]Captopril to angiotensin converting enzyme.
- [3H]Captopril binding assays are a valuable tool for elucidating ACE localization and function.
- This method can aid in defining the pharmacologic actions of captopril and related compounds.