Pharmacological properties of angiotensin II receptors in cultured rabbit gingival fibroblasts

• Published in: Comparative biochemistry and physiology. Toxicology & pharmacology 2004-03, Vol.137 (3), p.281-289
• Main Authors: Ohuchi, Nozomi, Hayashi, Kazuhiko, Koike, Katsuo, Kizawa, Yasuo, Kusama, Tadashi, Ohsawa, Masami, Taniguchi, Yumiko, Iwamoto, Keishi, Sano, Masakazu, Murakami, Hajime
• Format: Article
• Language: English
• Subjects: [ 3H]angiotensin II; [ 3H]DuP753; Angiotensin II - metabolism; Angiotensin II - pharmacology; Angiotensin II Type 1 Receptor Blockers - pharmacology; Angiotensin Receptor Antagonists; Animals; Benzimidazoles - pharmacology; Binding assay; Binding, Competitive - drug effects; Blotting, Western; Cell Division - drug effects; Cells, Cultured; Cultured gingival fibroblasts; Dose-Response Relationship, Drug; Fibroblasts - drug effects; Fibroblasts - metabolism; Gingiva - cytology; Gingival overgrowth; Kinetics; Losartan - pharmacology; Proliferation; Rabbit; Rabbits; Radioligand Assay; Receptor; Receptors, Angiotensin - metabolism; Saralasin - pharmacology; Tetrazoles - pharmacology; Tritium
• ISSN: 1532-0456; 1878-1659
• DOI: 10.1016/j.cca.2004.02.003

We demonstrated that angiotensin II (Ang II, 10–1000 nM) induced proliferation of cultured rabbit gingival fibroblasts in a concentration-dependent manner. The Ang II-induced proliferation was inhibited by CV-11974 (AT 1 antagonist; 1 μM) and saralasin (AT 1/AT 2 antagonist; 1 μM), but not by PD123,319 (AT 2 antagonist; 1 μM), suggesting that Ang II-induced proliferation was mediated via AT 1 receptors present in and/or on gingival fibroblasts. The results of Western blot analysis indicated the presence of AT 1 and AT 2 receptors in/on the fibroblasts. In a subsequent radioligand binding assay, the binding of [ 3H]Ang II to the fibroblasts was specific and saturable with both high- and low-affinity sites. Competition binding experiments indicated that Ang II completely displaced [ 3H]Ang II binding, and CV-11974 and PD123,319 maximally displaced up to approximately 63% and 37% of the total binding, respectively. Ang II and CV-11974 completely displaced the [ 3H]DuP753 binding but PD123,319 did not, indicating a single population of binding site. These findings demonstrate that gingival fibroblasts contain both AT 1 and AT 2 receptor subtypes for Ang II, and support that Ang II stimulation of AT 1 receptors results in proliferation of the fibroblasts.