The selective endothelin ETA receptor antagonist BQ123 antagonizes endothelin-1-mediated mitogenesis

Area of Science:

• Cardiovascular Biology
• Molecular Pharmacology
• Cell Signaling

Background:

• Endothelin isopeptides are potent vasoactive substances.
• Vascular smooth muscle cell proliferation is crucial in cardiovascular diseases.
• The role of specific endothelin receptors in cell growth requires clarification.

Purpose of the Study:

• To investigate the mitogenic effects of endothelin-1 (ET-1) and endothelin-3 (ET-3) in rat aortic vascular smooth muscle cells.
• To determine the specific endothelin receptor subtype mediating ET-1's mitogenic action.
• To evaluate the efficacy of the selective ETA receptor antagonist BQ123.

Main Methods:

• Primary cell culture of rat aortic vascular smooth muscle cells.
• Measurement of [3H]thymidine incorporation to assess DNA synthesis.
• Application of endothelin isopeptides (ET-1, ET-3) and sarafotoxin 6c.
• Treatment with the selective ETA receptor antagonist BQ123.

Main Results:

• ET-1 and ET-3 induced concentration-dependent increases in [3H]thymidine incorporation.
• The ETB-selective agonist sarafotoxin 6c showed no significant mitogenic effect.
• BQ123 selectively inhibited ET-1-induced [3H]thymidine incorporation in a concentration-dependent manner.

Conclusions:

• Endothelin-1-mediated mitogenesis in vascular smooth muscle cells is primarily mediated by the ETA receptor.
• These findings highlight the ETA receptor as a key target for modulating vascular smooth muscle cell proliferation.