endothelin
Summary
Endothelin is a potent vasoconstrictor peptide produced primarily by vascular endothelial cells. ET-1 is the most clinically significant isoform, playing crucial roles in vascular tone regulation, and is implicated in hypertension, heart failure, and pulmonary arterial hypertension.
Detail
Endothelin is a 21-amino acid peptide hormone with three isoforms (ET-1, ET-2, ET-3), with ET-1 being the most physiologically important. It is synthesized from big endothelin by endothelin-converting enzyme (ECE) and acts through two G-protein coupled receptors: ETA (found on vascular smooth muscle, causes vasoconstriction) and ETB (found on endothelium and smooth muscle, mediates both vasodilation via NO release and vasoconstriction). ET-1 is one of the most potent vasoconstrictors known, with effects lasting several hours. It also promotes smooth muscle proliferation, fibrosis, and inflammation. Elevated levels are associated with various cardiovascular diseases including systemic and pulmonary hypertension, atherosclerosis, heart failure, and renal disease. Endothelin receptor antagonists (bosentan, ambrisentan, macitentan) are used therapeutically in pulmonary arterial hypertension. The endothelin system represents an important balance between vasoconstriction/proliferation and vasodilation/anti-proliferation, with dysregulation contributing to vascular pathology.
Sources
- Costanzo Physiology 6th Edition
- Katzung Basic & Clinical Pharmacology 14th Edition
- Harrison's Principles of Internal Medicine 21st Edition
- Boron & Boulpaep Medical Physiology 3rd Edition
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