Endothelin-1
Also known as: Big endothelin-1 (precursor), EDN1, Endothelin‑1, ET-1, Preproendothelin-1 (mature form), Vasoconstrictin
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Summary
Endothelin‑1 (ET‑1) is a 21‑amino‑acid vasoactive peptide that acts as a powerful vasoconstrictor and bronchoconstrictor. It is investigated in research settings for its role in ocular diseases such as diabetic retinopathy and glaucoma, in migraine pathophysiology, and in airway hyper‑reactivity. Elevated circulating or ocular ET‑1 levels have been reported in several clinical conditions, prompting interest in its use as a biomarker or therapeutic target, although no approved drug formulations exist.
Mechanism of Action
ET‑1 binds to endothelin receptor type A (ETA) and type B (ETB) on vascular smooth‑muscle and endothelial cells. Activation of ETA triggers G‑protein‑mediated phospholipase C signaling, raising intracellular calcium and causing potent vasoconstriction and bronchoconstriction. ETB receptors can mediate vasodilation via nitric‑oxide release, but in many tissues the net effect of ET‑1 is vasoconstriction, increased vascular resistance, and modulation of ocular blood flow and neuronal excitability.
What the Research Shows
Meta‑analyses show that patients with diabetic retinopathy have significantly higher circulating ET‑1 than controls (standardised mean difference ≈ 1.7). Similar elevations are reported in plasma and aqueous humor of glaucoma patients across subtypes (SMD ≈ 1.2‑1.6). In migraine, early‑phase attacks are associated with raised plasma ET‑1 and genetic variants in the ETA receptor; animal studies demonstrate that ET‑1 can provoke cortical spreading depression. An inhalation study in asthmatics revealed dose‑dependent bronchoconstriction, about 100‑fold more potent than methacholine. A systematic review of phosphodiesterase‑5 inhibitor trials noted a modest, bias‑sensitive reduction in ET‑1 levels, while curcumin supplementation showed no consistent effect on ET‑1.
Reported Benefits
The strongest evidence supports ET‑1 as a biomarker: elevated levels correlate with disease severity in diabetic retinopathy and multiple glaucoma types, suggesting utility for monitoring progression. Experimental data indicate that antagonising ET‑1 receptors may attenuate migraine attacks, and bronchoconstriction studies confirm its role as a potent airway mediator, informing potential therapeutic strategies.
Limitations of the Evidence
Most findings are observational and derived from meta‑analyses of heterogeneous studies; causality cannot be inferred. The migraine literature includes limited human trials (one small antagonist study) and relies heavily on animal models. The PDE‑5 inhibitor meta‑analysis reported high heterogeneity and possible publication bias, weakening confidence in ET‑1 reduction claims. No large‑scale interventional trials directly targeting ET‑1 in these conditions have been published.
Safety Considerations
Endogenous ET‑1 is essential for normal vascular tone, but exogenous administration can provoke severe vasoconstriction and bronchoconstriction. Inhaled ET‑1 caused rapid, dose‑dependent airway narrowing in asthmatic subjects, reversible with bronchodilators. Systemic infusion may affect blood pressure, as modest systolic changes were observed in healthy volunteers. Because no therapeutic product is approved, any experimental use should be confined to controlled research settings with monitoring for respiratory and cardiovascular effects.
How It Is Administered
Research protocols have delivered ET‑1 by intracoronary, intrathecal, or intravenous infusion, typically as a sterile peptide solution. Dosing regimens vary widely between studies and are not standardised. Administration is performed under strict clinical monitoring, especially for cardiovascular and respiratory parameters.
Routes of Administration
Goals & Uses
- Research tool for vasoconstriction studiesResearchHigh
- Model of renal vasoconstriction and injuryResearchModerate
- Pharmacological target for PAH treatmentTherapeutic TargetHigh
- Cancer biology research (tumor angiogenesis)ResearchModerate
- Biomarker for pulmonary arterial hypertensionDiagnostics / BiomarkerHigh
Contraindications
- Systemic administration in humans outside controlled researchGeneralHigh
- Coronary artery diseaseCardiovascularHigh
- Renal impairmentOrgan DysfunctionHigh
- Pre-existing severe hypertensionCardiovascularHigh
Adverse Effects
- Pulmonary vasoconstrictionPulmonaryCommon
- Nausea and flushingGeneralCommon
- Myocardial ischemia / coronary vasospasmCardiovascularUncommon
- BronchoconstrictionRespiratoryUncommon
- Severe vasoconstriction / hypertensionCardiovascularCommon
- Renal vasoconstriction and reduced GFRRenalCommon
Drug Interactions
- Endothelin receptor antagonists (bosentan, ambrisentan, macitentan)High
- Vasopressors (e.g., norepinephrine, vasopressin)High
- Nitric oxide donors / nitratesModerate
- ACE inhibitorsLow
Population Constraints
- Patients with heart failureCardiovascularAbsolute
- Patients with chronic kidney diseaseRenalRelative
- Pregnant womenReproductiveAbsolute
- Neonates and pediatric populationsPediatricAbsolute
Regulatory Status
- European UnionUnapprovedNot approved by EMA as a therapeutic agent. Used only in controlled research settings.
- United StatesUnapprovedNot an approved therapeutic; classified as a research peptide. Endothelin pathway antagonists (not ET-1 itself) are FDA-approved for PAH.
- United KingdomUnapprovedNot approved by MHRA as a medicine. Used as a research tool only.
Endothelin‑1 is an endogenous peptide and is not approved as a pharmaceutical product.
Evidence & Sources
- Journal ArticleHighSun X, et al.2026-01-01T00:00:00.000000Z
- Journal ArticleHighD'Andrea S, et al.2019-01-01T00:00:00.000000Z
- Journal ArticleHighIljazi A, et al.2018-01-01T00:00:00.000000Z
- Journal ArticleHighHallajzadeh J, et al.2019-01-01T00:00:00.000000Z
- Journal ArticleHighLampsas S, et al.2024-01-01T00:00:00.000000Z
- Journal ArticleModerateChalmers GW, et al.1997-01-01T00:00:00.000000Z
Frequently Asked Questions
Is endothelin‑1 used as a clinical test for eye diseases?
Current evidence shows that ET‑1 levels are higher in diabetic retinopathy and glaucoma, but no validated clinical assay or regulatory approval exists. It remains a research biomarker rather than a routine diagnostic test.
Can blocking endothelin‑1 help treat migraine?
One small randomized trial evaluated an endothelin antagonist for acute migraine with mixed results, and animal data support a mechanistic link. Larger, well‑controlled studies are needed before any therapeutic recommendation.
Why does inhaled endothelin‑1 cause bronchoconstriction?
ET‑1 activates ETA receptors on airway smooth‑muscle, triggering calcium‑mediated contraction that is far more potent than methacholine. In asthmatic subjects this leads to rapid narrowing of the airways, reversible with bronchodilators.
Are there any approved drugs that target endothelin‑1?
No endothelin‑1–targeting drugs are approved for the conditions discussed here. Existing endothelin receptor antagonists are approved for pulmonary arterial hypertension, but their use in diabetic retinopathy, glaucoma, or migraine remains investigational.
What routes are used to study endothelin‑1 in humans?
Research studies have administered ET‑1 intravenously, intracoronarily, or intrathecally, usually as a short‑term infusion under intensive monitoring of blood pressure and respiratory function.
What is Endothelin-1?
Endothelin‑1 (ET‑1) is a 21‑amino‑acid vasoactive peptide that acts as a powerful vasoconstrictor and bronchoconstrictor. It is investigated in research settings for its role in ocular diseases such as diabetic retinopathy and glaucoma, in migraine pathophysiology, and in airway hyper‑reactivity. Elevated circulating or ocular ET‑1 levels have been reported in several clinical conditions, prompting interest in its use as a biomarker or therapeutic target, although no approved drug formulations exist.
What is Endothelin-1 used for?
Endothelin-1 is educationally associated with: Research tool for vasoconstriction studies, Model of renal vasoconstriction and injury, Pharmacological target for PAH treatment, Cancer biology research (tumor angiogenesis), Biomarker for pulmonary arterial hypertension. Educational only — not medical advice.
How is Endothelin-1 administered?
Recorded routes of administration: Intracoronary, Intrathecal, Intravenous.
What are the potential side effects of Endothelin-1?
Reported adverse effects include: Pulmonary vasoconstriction, Nausea and flushing, Myocardial ischemia / coronary vasospasm, Bronchoconstriction, Severe vasoconstriction / hypertension, Renal vasoconstriction and reduced GFR. This list is not exhaustive — consult a qualified clinician.
Who should avoid Endothelin-1?
Recorded contraindications: Systemic administration in humans outside controlled research, Coronary artery disease, Renal impairment, Pre-existing severe hypertension. Consult a qualified clinician before use.