# Cardiovascular Research Peptides: Families, Reagent Formats and Selection Notes > Two opposing hormone systems define this catalogue section. Here is what sits in it, which format answers which question, and how the handling differs. Web page: https://peptidemedixeu.com/en/learn/research-catalog-cardiovascular/ · Peptide Medix EU · 3 min read · Updated: 2026-08-14 Two opposing hormone systems shape cardiovascular peptide research: the vasoconstrictor renin-angiotensin and endothelin axes on one side and the vasodilator natriuretic peptides on the other, with a widening set of endothelium- and adipose-derived regulators alongside them. Our cardiovascular topic page gathers the peptide standards, antisera, tracers and [immunoassay kits](https://peptidemedixeu.com/en/learn/research-catalog-type-assay-kits/) that this literature relies on. This guide describes which families the topic contains, the purpose each serves and the reagent format that suits each experimental question. ## Scope of the cardiovascular topic A family belongs here when its parent peptide is made by, or acts upon, the heart, vasculature, kidney or the neuroendocrine circuitry governing blood pressure and volume. That takes in circulating hormones, locally acting paracrine peptides and the biomarkers used to characterise animal models of hypertension, heart failure and vascular injury. Some families appear under more than one topic: angiopoietin also belongs to [cancer angiogenesis](https://peptidemedixeu.com/en/learn/peptides-for-healing-and-recovery-research-overview/) work, while apelin and adrenomedullin recur in metabolic studies. Everything listed is supplied for in-vitro and approved animal research only, and nothing is a diagnostic or therapeutic product. ## Natriuretic peptides as the biomarker backbone This family is ordered more than any other in the topic, because ANP and BNP serve as the standard indicators of cardiac load in animal models: - ANP: released on atrial stretch, 28 residues long, stocked as the mature hormone, as proANP fragments and across species variants. - BNP: the B-type hormone plus NT-proBNP, the cleaved N-terminal piece that prevails in biomarker studies thanks to its greater plasma stability relative to the active molecule. - CNP: endothelial in origin, signals at NPR-B, and appears in studies of vessel tone and skeletal growth instead of volume control. - DNP: isolated from Dendroaspis venom and employed as a pharmacological probe at the receptors. All four are usually ordered alongside matching EIA kits, since the quantitative question is normally plasma concentration within a model. ## Vasoconstrictor and pressure-regulating families - Angiotensin: the topic's biggest family, spanning Ang I, Ang II, Ang-(1–7), Ang IV and analogues selective for particular receptors, with Ang-(1–7) acting at Mas now the most rapidly growing area of renin-angiotensin study. - Endothelin: ET-1 through ET-3 plus their big-endothelin precursors. Nothing endogenous constricts vessels more powerfully than ET-1, which is why it serves as a standard positive control when reactivity is assayed. - Urotensin II: a cyclic molecule whose constrictor potency swings widely from one vascular bed or organism to the next, making a species-matched standard unusually critical. - Vasopressin with copeptin: the antidiuretic hormone alongside the durable C-terminal piece of its precursor. Laboratories quantify copeptin rather than the hormone itself because the latter falls apart in plasma. - Bradykinin: the vasodilator side of the kallikrein-kinin system, supplied as the nonapeptide itself, as des-Arg derivatives and as probes for the B1 and B2 receptors. ## Regulators from endothelium and adipose tissue - Apelin with ELABELA (Toddler): the pair of natural ligands at APJ. Potency and stability shift substantially between apelin-13, its pyroglutamated version, apelin-17 and apelin-36, so name the isoform every time. - Adrenomedullin with intermedin (AM2): vasodilators of the CGRP superfamily, examined in models of sepsis, failing hearts and leaky vasculature. - CGRP: available as the α and β forms together with CGRP(8–37) for blockade, covering vascular as well as neurogenic questions. - Urocortin: a member of the CRF family reported to protect cardiac tissue strongly in ischaemia-reperfusion work. - Catestatin, chromogranin A and salusin: chromogranin-derived and allied sequences active in autonomic and vascular contexts. - Adropin and EC-SOD: markers of endothelial performance and oxidative stress, now often run together with metabolic phenotyping. - Ac2-26: annexin A1's N-terminal sequence, an agonist at formyl peptide receptors and a common pro-resolving control where vascular inflammation is studied. - PF4 and thrombospondin: platelet products that connect clotting research with new vessel formation. - Relaxin: a hormone with vasodilatory and antifibrotic properties, used in heart-failure and pregnancy-adaptation research. ## Formats available in this topic Agonists, blocking fragments and calibrators for immunoassays all come as synthetic standards. Tracers carry more weight in this field than most, because autoradiography of receptors and competition binding in vascular tissue have historically relied on [I-125](https://peptidemedixeu.com/en/glossary/i-125-radiolabel/) forms of angiotensin II, endothelin-1 and ANP. Sections of heart, kidney and vessel are stained using polyclonal antisera. Most quantitative demand falls on EIA and [RIA](https://peptidemedixeu.com/en/glossary/ria/) kits, given how routinely plasma ANP, BNP, endothelin-1 and copeptin are measured in rodents. Magnetic beads cover pull-down and receptor-capture applications. ## Choosing within a family Three decisions recur. Which processed form do you need? BNP or NT-proBNP, apelin-13 or apelin-36, the big precursor or mature ET-1 — each pair represents two distinct analytes, and calibration against one gives wrong numbers for the other. Which organism? Natriuretic sequences diverge sufficiently between rodents and humans that a human-calibrated kit reads low on mouse plasma, so each listing declares its tested [species reactivity](https://peptidemedixeu.com/en/glossary/species-reactivity/). Are you blocking or stimulating? CGRP(8–37), des-Arg bradykinin derivatives and Ang-(1–7) function as receptor probes and cannot stand in for the parent molecule when quantifying. Where the endpoint is how much analyte a sample holds, buying a kit beats assembling antibody, tracer and standards. ## Handling notes specific to this topic Two properties govern bench practice here. A great many of these sequences close into rings via [disulfide bonds](https://peptidemedixeu.com/en/glossary/cyclic-peptide/) — two in endothelin-1, one apiece in ANP and urotensin II — so any reducing environment or thiol-containing buffer destroys their activity. Others vanish quickly once in plasma, which explains why durable precursor pieces like NT-proBNP and copeptin took over as the measured analytes, and why adding protease inhibitors at collection counts for as much as the reagent you chose. Beyond that, ordinary practice applies: vials sealed and frozen at −20 °C, reconstituted material split into single-use portions, and no repeated freeze-thaw. See the [storage guide](https://peptidemedixeu.com/en/learn/how-to-store-peptides/), the aliquoting guide and the COA guide for confirming peptide content. ## Further reading Browse the complete cardiovascular topic, the heart and vasculature hub or the natriuretic peptide system hub. Neighbouring guides cover the [diabetes](https://peptidemedixeu.com/en/learn/research-catalog-diabetes/) and metabolism section, which shares apelin and adrenomedullin, and the cancer section for the angiogenesis families. ## Frequently asked questions ### BNP or NT-proBNP for a rodent model? NT-proBNP suits most designs. The N-terminal fragment clears more slowly and holds up far better in collected plasma than active BNP, which improves reproducibility. Choose active BNP only when the biologically active species is specifically required, and check the kit's declared analyte and species calibration before ordering. ### Why are there so many apelin isoforms in the catalogue? Processing yields genuinely distinct molecules. Apelin-13, its pyroglutamated form, apelin-17 and apelin-36 differ in receptor potency, plasma stability and internalisation, with the pyroglutamated form predominating in plasma. Specify whichever isoform your protocol calls for, since substituting one alters the result rather than merely the concentration. ### Do endothelin peptides require special handling? They do. ET-1 depends on two disulfide bridges for its conformation, so keep reducing agents such as DTT or beta-mercaptoethanol out of reconstitution and assay buffers. It also adsorbs strongly to plastic, so siliconised tubes or a carrier protein in the diluent cut losses at low concentrations. ### Where should renin-angiotensin work begin? With the angiotensin family page, which collects Ang I, Ang II, Ang-(1–7), Ang IV, receptor-selective analogues and matching antisera in one location. If converting-enzyme substrates and downstream families are also needed, the RAS pathway hub is the better starting point. ### Are I-125 labelled cardiovascular peptides still in use? They are, especially for receptor autoradiography on tissue sections and classical competition binding, where the sensitivity is difficult to match. Isotope half-life imposes scheduling constraints, and appropriate licensing and waste handling are required. Fluorescent and biotinylated alternatives exist, and the labelled peptides guide compares them. ### Can these peptides be used in human blood pressure studies? No. Everything in the research catalogue is supplied for in-vitro and approved animal research. Some of these molecules have approved therapeutic counterparts, but catalogue material is not manufactured to pharmaceutical standards. --- For laboratory research use only. This page is provided for scientific and educational information. Materials referenced here are sold strictly for in-vitro laboratory research by qualified professionals — not for human or veterinary use, and nothing on this page is medical advice.