Endothelin: Physiology and What Research Reports

What endothelin is

Endothelin refers to a small family of 21-amino-acid peptides, of which endothelin-1 (ET-1) is the best characterised. The peptides are distinguished by two internal disulphide bridges that lock them into a compact, rigid structure — a shape that structural biologists have continued to revisit decades after the peptide's discovery, as described in a structural biology commentary on endothelin (PMID 30605124). A retrospective review marking twenty-five years of endothelin research framed the field as a mature but still expanding area of peptide pharmacology (PMID 25238993).

Endothelin is not a research peptide in the sense of a compound marketed for experimental administration. It is an endogenous signalling molecule — something the body makes — and most of the literature concerns either measuring it as a biomarker or blocking its receptors pharmacologically. Readers usually meet the term through cardiovascular or pulmonary medicine rather than through peptide supplementation discussions.

Where endothelin is produced

The peptide takes its name from the endothelium, the single-cell lining of blood vessels, which is its principal source. Expression is not limited to blood vessels, however. A developmental biology review reported that endothelin signalling operates during embryogenesis in neural crest–derived tissues and other developing structures (PMID 38078652). A review of the retina described endothelin ligands and receptors as being present in multiple retinal cell populations with diverse local roles (PMID 31884664). In skin, an experimental study reported that endothelin-1 induced and then inactivated tyrosinase in normal cultured human melanocytes, linking the peptide to pigment-cell biology (PMID 16035647).

Receptors and signalling

Endothelin acts through G-protein-coupled receptors conventionally designated ETA and ETB. A themed journal section devoted to endothelin summarised the breadth of this receptor pharmacology across organ systems (PMID 23278331), and the twenty-five-year retrospective described how receptor-selective and dual antagonists shaped the next generation of investigation (PMID 25238993).

How endothelin is measured and studied

Three broad approaches dominate the literature. First, measurement: circulating endothelin-1 concentrations are quantified in plasma and related to clinical outcomes, an approach reviewed in an analysis of endothelin-1 levels and cardiovascular events (PMID 30765295). Second, isolated tissue pharmacology: a study of human mammary and radial artery segments examined the effects of endothelin-receptor activation in conduit vessels used for bypass grafting (PMID 15553936). Third, receptor blockade, in which antagonists are used to infer what the endogenous system does, a strategy discussed in a commentary on endothelin's place in resistant hypertension (PMID 36603580).

What the literature reports by organ system

Blood vessels and blood pressure

Vascular effects are the most studied aspect of the peptide. Researchers examining human internal mammary and radial artery preparations reported that endothelin-receptor activation produced measurable vascular responses in these grafting conduits (PMID 15553936). At the clinical end, a commentary described the addition of endothelin-directed therapy as a further step beyond the conventional "ABCD" drug classes in resistant hypertension (PMID 36603580). A separate review of endothelin-1 levels and cardiovascular events reported associations between measured peptide concentrations and cardiovascular outcomes (PMID 30765295).

Kidney

A dedicated nephrology review reported that endothelin acts within the renal microcirculation, where the system contributes to the regulation of regional blood flow and vascular tone (PMID 25966346). This is one reason kidney-focused investigators track endothelin alongside more familiar renal hormone systems.

Lung

Pulmonary arterial hypertension is the setting in which endothelin-receptor antagonists became established therapeutics. A paediatric case report described pulmonary arterial hypertension associated with impaired lysosomal degradation of endothelin-1, illustrating how clearance — not only production — can shape peptide exposure (PMID 24910177).

Eye, skin and development

A review of the retina reported diverse endothelin roles in retinal vascular and neural tissue (PMID 31884664). In pigment cells, the study of cultured human melanocytes reported that endothelin-1 both induced and subsequently inactivated tyrosinase, the rate-limiting enzyme of melanin synthesis (PMID 16035647). In embryology, endothelin signalling was reported to be required for normal development of specific lineages (PMID 38078652).

Endothelial inflammation

During the COVID-19 pandemic, a hypothesis paper proposed that endotheliitis and endothelin signalling contributed to vascular manifestations of the illness and raised endothelin receptor blockers as a research question (PMID 33823371). That paper was explicitly framed as a hypothesis rather than as trial evidence.

Interpreting Endothelin Findings: What Studies Report

Several cautions recur in the cited literature. Circulating endothelin-1 is an association marker in the cardiovascular outcome literature, and the review reporting those associations did not establish that the peptide causes the events it tracks with (PMID 30765295). Isolated-vessel work is informative about local pharmacology but was conducted in excised tissue rather than in intact circulation (PMID 15553936). Single-patient reports, such as the pulmonary arterial hypertension case linked to impaired lysosomal endothelin-1 degradation, describe one individual and are not generalisable (PMID 24910177). Hypothesis papers propose mechanisms for testing rather than reporting results (PMID 33823371). This page is for educational purposes only and is not medical advice; consult a licensed physician about any health condition, medication or laboratory result.

Why the term matters to peptide readers

Endothelin appears in peptide-literature discussions for three reasons. It is a textbook example of a short, disulphide-constrained peptide whose structure dictates receptor activity (PMID 30605124). It demonstrates how a single peptide family can operate across vascular, renal, retinal, dermal and developmental biology (PMID 23278331). And it is one of the clearest cases in which peptide pharmacology translated into receptor-antagonist drug development, a trajectory summarised in the twenty-five-year review of the field (PMID 25238993). Readers encountering the word in a laboratory report or a review article are almost always meeting an endogenous regulator, not an administered compound.

References

• Themed section: endothelin (British Journal of Pharmacology, 2013)
• Endothelin-1 levels and cardiovascular events (Trends in Cardiovascular Medicine, 2020)
• Endothelin signaling in development (Development, 2023)
• New Insights into Endothelin Signaling and Its Diverse Roles in the Retina (Advances in Experimental Medicine and Biology, 2019)
• Endotheliitis, endothelin, and endothelin receptor blockers in COVID-19 (Medical Hypotheses, 2021)
• Never too late for endothelin (Acta Crystallographica Section F, 2019)
• From ABCD to E for endothelin in resistant hypertension (Cell, 2023)
• Endothelin and the renal microcirculation (Seminars in Nephrology, 2015)
• Tyrosinase induction and inactivation in normal cultured human melanocytes by endothelin-1 (International Journal of Tissue Reactions, 2005)
• 25 years of endothelin research: the next generation (Life Sciences, 2014)
• Endothelin and effects of endothelin-receptor activation in the mammary and radial artery (Scandinavian Cardiovascular Journal, 2004)
• Pulmonary arterial hypertension associated with impaired lysosomal endothelin-1 degradation (Cardiology in the Young, 2015)