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Angiotensin II receptor heterogeneity
W F Herblin1, A T Chiu, D E McCall
1DuPont Merck Pharmaceutical Company, Wilmington, DE 19880-0400.
American Journal of Hypertension
|April 1, 1991
Summary
This study identifies two distinct angiotensin II (AII) receptors, AII-1 and AII-2, with different sensitivities and distributions in rat and rabbit tissues. Understanding these AII receptor subtypes is key for developing targeted therapies.
Area of Science:
- Pharmacology
- Endocrinology
- Molecular Biology
Background:
- Previous research suggested heterogeneity within the angiotensin II (AII) receptor system.
- Observed incomplete inhibition of AII binding to adrenal membranes indicated distinct receptor populations.
Purpose of the Study:
- To investigate the heterogeneity of angiotensin II receptors.
- To characterize the distinct properties and distribution of identified AII receptor subtypes.
Main Methods:
- Autoradiography was used to visualize AII receptor binding sites in rat and rabbit adrenal glands and kidneys.
- Ligand binding studies were employed to confirm and differentiate receptor subtypes.
- Sensitivity to thiol reagents like dithiothreitol (DTT) and specific antagonists (DuP 753, EXP655) were assessed.
Main Results:
- Two AII receptor subtypes, AII-1 and AII-2, were identified based on differential sensitivity to DTT and DuP 753.
- AII-1 receptors (80% in rat adrenal cortex) are sensitive to DTT and DuP 753.
- AII-2 receptors, found in residual rat adrenal cortex, medulla, and rabbit kidney capsule, are insensitive to DTT and DuP 753 but bind EXP655.
- Angiotensin III shows higher affinity for AII-2 receptors.
Conclusions:
- The angiotensin II system exhibits receptor heterogeneity with at least two distinct subtypes, AII-1 and AII-2.
- These receptor subtypes display differential tissue distribution and ligand affinities.
- Further research into AII receptor subtypes and their functions will enable the development of more selective therapeutic strategies.