Subtopic Deep Dive
Vasoconstrictor Activity of Urotensin II
Research Guide
What is Vasoconstrictor Activity of Urotensin II?
Vasoconstrictor activity of urotensin II refers to the potent contraction of vascular smooth muscle induced by human urotensin-II (hU-II) via its receptor GPR14 (UT), often exceeding endothelin-1 potency in isolated arteries.
Human urotensin-II acts as the most potent mammalian vasoconstrictor identified, binding orphan receptor GPR14 to trigger RhoA/Rho-kinase mediated contraction (Ames et al., 1999; 788 citations). Studies compare its effects across species in rat, mouse, dog, pig, marmoset, and monkey arteries, revealing variable potency (Douglas et al., 2000; 227 citations). Receptor localization shows high density in brainstem and vascular tissues (Maguire et al., 2000; 245 citations). Over 20 key papers span 1999-2014.
Why It Matters
Urotensin II signaling regulates vascular tone and contributes to hypertension via oxidative stress pathways (Rodrigo et al., 2011; 427 citations). Its RhoA/Rho-kinase mechanism drives arterial smooth muscle proliferation, linking to cardiovascular disease management (Sauzeau et al., 2001; 259 citations; Douglas and Ohlstein, 2000; 193 citations). Antagonism studies, like apelin countering Ang II, highlight therapeutic targeting for vasospasm and portal hypertension (Chun et al., 2008; 324 citations; Iwakiri, 2011; 190 citations). Drug-induced hypertension models reveal VEGF-related mechanisms relevant to urotensin pathways (Veronese et al., 2006; 320 citations).
Key Research Challenges
Species-variable potency
hU-II vasoconstriction potency varies markedly across rat, mouse, dog, pig, marmoset, and monkey arteries, complicating translation to humans (Douglas et al., 2000). This differential activity challenges uniform therapeutic modeling. Over 200 citations underscore inconsistent responses.
Receptor localization precision
GPR14 (UT) distribution peaks in brainstem abducens nucleus but varies in peripheral vessels, hindering targeted interventions (Maguire et al., 2000). Quantifying [125I]-U-II binding densities (up to 139.6 amol/mm²) requires advanced autoradiography. Tissue-specific expression gaps persist.
Oxidative stress integration
Linking hU-II RhoA/Rho-kinase pathways to hypertension oxidative stress remains incomplete despite inhibitor studies like Y-27632 (Sauzeau et al., 2001; Rodrigo et al., 2011). Mechanisms overlap with endothelial dysfunction but lack direct hU-II models. Over 400 combined citations highlight this void.
Essential Papers
Human urotensin-II is a potent vasoconstrictor and agonist for the orphan receptor GPR14
Robert S. Ames, Henry M. Sarau, Johathan K. Chambers et al. · 1999 · Nature · 788 citations
The role of oxidative stress in the pathophysiology of hypertension
Ramón Rodrigo, Jaime González, Fabio Paoletto · 2011 · Hypertension Research · 427 citations
Apelin signaling antagonizes Ang II effects in mouse models of atherosclerosis
Hyung J. Chun, Ziad A. Ali, Yoko Kojima et al. · 2008 · Journal of Clinical Investigation · 324 citations
Apelin and its cognate G protein-coupled receptor APJ constitute a signaling pathway with a positive inotropic effect on cardiac function and a vasodepressor function in the systemic circulation. T...
Mechanisms of Hypertension Associated With BAY 43-9006
Maria Luisa Veronese, Ari Mosenkis, Keith T. Flaherty et al. · 2006 · Journal of Clinical Oncology · 320 citations
Purpose BAY 43-9006 (sorafenib) is an inhibitor of Raf kinase, the vascular endothelial growth factor (VEGF) receptor-2, and angiogenesis in tumor xenografts. The current study investigated the inc...
Human Urotensin II–Induced Contraction and Arterial Smooth Muscle Cell Proliferation Are Mediated by RhoA and Rho-Kinase
Vincent Sauzeau, Erik Le Mellionnec, Jacques Bertoglio et al. · 2001 · Circulation Research · 259 citations
The aim of this work was to investigate the coupling of human urotensin II (hU-II) to RhoA activation and regulation of RhoA-dependent functions. The use of the Rho-kinase inhibitor Y-27632 and the...
Orphan‐receptor ligand human urotensin II: receptor localization in human tissues and comparison of vasoconstrictor responses with endothelin‐1
Janet J. Maguire, Rhoda E. Kuc, Anthony P. Davenport · 2000 · British Journal of Pharmacology · 245 citations
We have determined the distribution of receptors for human urotensin‐II (U‐II) in human and rat CNS and peripheral tissues. In rat, [ 125 I]‐U‐II binding density was highest in the abducens nucleus...
Differential vasoconstrictor activity of human urotensin‐II in vascular tissue isolated from the rat, mouse, dog, pig, marmoset and cynomolgus monkey
Stephen A. Douglas, Anthony C. Sulpizio, Valerie Piercy et al. · 2000 · British Journal of Pharmacology · 227 citations
Urotensin‐II (U‐II) and its G‐protein‐coupled receptor, GPR14, are expressed within mammalian cardiac and peripheral vascular tissue and, as such, may regulate mammalian cardiovascular function. Th...
Reading Guide
Foundational Papers
Start with Ames et al. (1999; 788 citations) for GPR14 discovery and potency baseline, then Sauzeau et al. (2001; 259 citations) for RhoA mechanism, followed by Maguire et al. (2000; 245 citations) for localization.
Recent Advances
González (2014; 194 citations) advances oxidative stress links; Iwakiri (2011; 190 citations) connects to endothelial dysfunction in hypertension models.
Core Methods
Autoradiography ([125I]-U-II binding), organ bath assays for contraction (rat/mouse arteries), inhibitors (Y-27632 for Rho-kinase), species comparisons (dog/pig/monkey tissues).
How PapersFlow Helps You Research Vasoconstrictor Activity of Urotensin II
Discover & Search
PapersFlow's Research Agent uses searchPapers('urotensin II vasoconstrictor GPR14') to retrieve Ames et al. (1999; 788 citations), then citationGraph to map 20+ citing works on species differences, and findSimilarPapers to uncover Douglas et al. (2000). exaSearch scans abstracts for Rho-kinase links, surfacing Sauzeau et al. (2001).
Analyze & Verify
Analysis Agent applies readPaperContent on Ames et al. (1999) to extract GPR14 potency data, then runPythonAnalysis to plot vasoconstriction EC50 curves from Douglas et al. (2000) using pandas/matplotlib. verifyResponse with CoVe cross-checks RhoA mediation claims against Sauzeau et al. (2001), earning GRADE A for methodological rigor in Y-27632 inhibition stats.
Synthesize & Write
Synthesis Agent detects gaps in species-to-human translation from Maguire et al. (2000) and Douglas et al. (2000), flagging oxidative stress overlaps (Rodrigo et al., 2011). Writing Agent uses latexEditText to draft methods sections, latexSyncCitations for 10+ refs, and latexCompile for figures; exportMermaid generates RhoA signaling pathway diagrams.
Use Cases
"Extract dose-response curves for hU-II vs endothelin-1 from rat arteries and plot potency ratios"
Research Agent → searchPapers → Analysis Agent → readPaperContent (Douglas et al., 2000) → runPythonAnalysis (pandas curve fitting, matplotlib EC50 plot) → researcher gets CSV of ratios and GRADE-verified graph.
"Write LaTeX review section on urotensin II Rho-kinase mechanisms with citations"
Synthesis Agent → gap detection (Sauzeau et al., 2001) → Writing Agent → latexEditText (intro text) → latexSyncCitations (Ames 1999, Sauzeau 2001) → latexCompile → researcher gets PDF-ready section with compiled equations.
"Find code for simulating urotensin II receptor binding models"
Research Agent → searchPapers('urotensin II GPR14 simulation') → paperExtractUrls → paperFindGithubRepo → githubRepoInspect → researcher gets validated Python sim code for KD binding from linked repo.
Automated Workflows
Deep Research workflow conducts systematic review: searchPapers(50+ urotensin hits) → citationGraph → DeepScan (7-step verify on Ames et al., 1999 potency) → structured report on vasoconstrictor hierarchies. Theorizer generates hypotheses linking hU-II to oxidative hypertension (Rodrigo et al., 2011) via RhoA gaps. DeepScan applies CoVe checkpoints to species data from Douglas et al. (2000).
Frequently Asked Questions
What defines vasoconstrictor activity of urotensin II?
hU-II induces potent vascular contraction via GPR14, often surpassing endothelin-1 in isolated arteries (Ames et al., 1999; 788 citations).
What are key methods for studying urotensin II vasoconstriction?
[125I]-U-II binding autoradiography localizes receptors; Rho-kinase inhibitor Y-27632 tests signaling in smooth muscle (Maguire et al., 2000; Sauzeau et al., 2001).
What are foundational papers?
Ames et al. (1999; 788 citations) identifies GPR14 agonism; Sauzeau et al. (2001; 259 citations) details RhoA mediation (Circulation Research).
What open problems exist?
Species potency variability impedes human translation; oxidative stress integration with hU-II pathways unresolved (Douglas et al., 2000; Rodrigo et al., 2011).
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