Urotensin II: the old kid in town

Dynamic changes of urotensin II and its receptor during ovarian development of olive flounder Paralichthys olivaceus

Urotensin II (UII) is a kind of fish somatostatins cyclic peptide, which was originally extracted from the caudal neurosecretory system (CNSS). The system of UII and UII receptor (UIIR) has been reported to have multiple physiological regulatory functions, such as cardiovascular control, osmoregulation, and lipid metabolism. However, the effect of UII and UIIR on the ovarian development has not been covered. This study investigated the expression pattern of UII and UIIR in the ovarian follicles and explored their impact on ovarian development in olive flounder Paralichthys olivaceus. The results showed that the highest UII and UIIR mRNA levels were observed at stage II and stage III follicles during ovarian development, respectively. In situ hybridization revealed that a strong signal of UII was expressed in the oocyte nuclei of stage II follicles, however, UIIR was found in the follicle cells and oocyte cytoplasm of stage II and stage III follicles. Similarly, immunohistochemistry found positive signal of UII was detected in the oocyte nuclei of stage II follicles. The results from in vitro culture of olive flounder follicles suggested the expression of UII and UIIR mRNA levels significantly increased by 10 IU/ml human chorionic gonadotropin (hCG) for 9 h. Furthermore, the transcriptional expression of UII and UIIR was not statistically significantly changed by 17α, 20β-dihydroxy-4-pregnen-3-one (DHP). These results firstly suggested that UII and UII receptor may play vital roles in regulating ovarian growth in olive flounder.

Evaluation of Endothelial Dysfunction in Bipolar Affective Disorders: Serum Endocan and Urotensin-II Levels

Objective

This study investigated changes in urotensin-II (U-II) and endocan levels which can be used as an early biological marker of endothelial injury in the episode and remission phases of bipolar affective disorder (BAD).

Methods

We compared endocan and U-II levels, which has been shown to be closely associated with neurotransmitter systems in addition to continuity of endothelial structure and inflammatory response, in patients with BAD in remission for at least one year (n=42) and in patients still in manic or depressive episodes (n=16) with healthy controls (n=30).

Results

Both endocan and U-II levels were significantly higher in the bipolar patients than in the controls. Endocan and U-II levels were also significantly correlated with one another (p=0.000, r=0.833). Both endocan (p=0.000) and U-II levels (p=0.000) were significantly higher in the bipolar attack group compared to the subjects in remission, and in the remission group compared to the controls.

Conclusion

In this study we determined significantly higher endocan and U-II levels in BAD compared to the controls, while serum endocan and U-II levels of patients undergoing attacks were also significantly higher than those of the controls and also those of patients in remission.

Chronic Urotensin-II Administration Improves Whole-Body Glucose Tolerance in High-Fat Diet-Fed Mice

Urotensin-II (U-II) is an endogenous peptide agonist of a G protein-coupled receptor-urotensin receptor. There are many conflicting findings about the effects of U-II on blood glucose. This study aims to explore the effects of U-II on glucose metabolism in high-fat diet-fed mice. Male C57BL/6J mice were fed a 45% high-fat diet or chow diet and were administered U-II intraperitoneally for in vivo study. Skeletal muscle C2C12 cells were used to determine the effects of U-II on glucose and fatty acid metabolism as well as mitochondrial respiratory function. In this study, we found that chronic U-II administration (more than 7 days) ameliorated glucose tolerance in high-fat diet-fed mice. In addition, chronic U-II administration reduced the weight gain and the adipose tissue weight, including visceral, subcutaneous, and brown adipose tissue, without a significant change in blood lipid levels. These were accompanied by the increased mRNA expression of the mitochondrial thermogenesis gene Ucp3 in skeletal muscle. Furthermore, in vitro treatment with U-II directly enhanced glucose and free fatty acid consumption in C2C12 cells with increased aerobic respiration. Taken together, chronic U-II stimulation leads to improvement on glucose tolerance in high-fat diet-fed mice and this effect maybe closely related to the reduction in adipose tissue weights and enhancement on energy substrate utilization in skeletal muscle.

Natural and synthetic peptides in the cardiovascular diseases: An update on diagnostic and therapeutic potentials

Several peptides play an important role in physiological and pathological conditions into the cardiovascular system. In addition to well-known vasoactive agents such as angiotensin II, endothelin, serotonin or natriuretic peptides, the vasoconstrictor Urotensin-II (Uro-II) and the vasodilators Urocortins (UCNs) and Adrenomedullin (AM) have been implicated in the control of vascular tone and blood pressure as well as in cardiovascular disease states including congestive heart failure, atherosclerosis, coronary artery disease, and pulmonary and systemic hypertension. Therefore these peptides, together with their receptors, become important therapeutic targets in cardiovascular diseases (CVDs). Circulating levels of these agents in the blood are markedly modified in patients with specific CVDs compared with those in healthy patients, becoming also potential biomarkers for these pathologies. This review will provide an overview of current knowledge about the physiological roles of Uro-II, UCN and AM in the cardiovascular system and their implications in cardiovascular diseases. It will further focus on the structural modifications carried out on original peptide sequences in the search of analogues with improved physiochemical properties as well as in the delivery methods. Finally, we have overviewed the possible application of these peptides and/or their precursors as biomarkers of CVDs.

The G Protein-Coupled Receptor UT of the Neuropeptide Urotensin II Displays Structural and Functional Chemokine Features

The urotensinergic system was previously considered as being linked to numerous physiopathological states, including atherosclerosis, heart failure, hypertension, pre-eclampsia, diabetes, renal disease, as well as brain vascular lesions. Thus, it turns out that the actions of the urotensin II (UII)/G protein-coupled receptor UT system in animal models are currently not predictive enough in regard to their effects in human clinical trials and that UII analogs, established to target UT, were not as beneficial as expected in pathological situations. Thus, many questions remain regarding the overall signaling profiles of UT leading to complex involvement in cardiovascular and inflammatory responses as well as cancer. We address the potential UT chemotactic structural and functional definition under an evolutionary angle, by the existence of a common conserved structural feature among chemokine receptorsopioïdergic receptors and UT, i.e., a specific proline position in the transmembrane domain-2 TM2 (P2.58) likely responsible for a kink helical structure that would play a key role in chemokine functions. Even if the last decade was devoted to the elucidation of the cardiovascular control by the urotensinergic system, we also attempt here to discuss the role of UII on inflammation and migration, likely providing a peptide chemokine status for UII. Indeed, our recent work established that activation of UT by a gradient concentration of UII recruits Gαi/o and Gα13 couplings in a spatiotemporal way, controlling key signaling events leading to chemotaxis. We think that this new vision of the urotensinergic system should help considering UT as a chemotactic therapeutic target in pathological situations involving cell chemoattraction.

Age-Related Reduction of Contractile Responses to Urotensin II Is Seen in Aortas from Wistar Rats but Not from Type 2 Diabetic Goto-Kakizaki Rats

Vascular dysfunction is a common finding in type 2 diabetes, although the response to urotensin II (UII), a potent vasoconstrictor peptide, remains unclear. We investigated whether a UII-induced contraction was increased in the aortas from type 2 diabetic Goto-Kakizaki (GK) rats at the chronic stage. At 36 or 37 weeks of age (older group), a UII-induced contraction was seen in GK rats and was reduced by a Rho kinase inhibitor or urotensin receptor (UT) antagonist, whereas UII failed to induce a contraction in aortas from age-matched Wistar rats. In UII-stimulated aortas, the expression of Rho kinases, Rho A, and phosphorylated myosin phosphatase target subunit 1 did not change between the two groups; however, phosphorylation of extracellular-regulated kinase 1/2 and p38 mitogen-activated protein kinase (MAPK) was greater in GK than in Wistar rats. Compared to intact aortas, UII-induced contractions were slightly, but not significantly, increased by endothelial denudation of the aortas of Wistar rats at 24 weeks of age. At 6 weeks of age (young group), the UII-induced contractions were seen in GK and Wistar groups. The total expression and the membrane-to-cytosol ratio of the UT protein slightly decreased in Wistar aortas with aging but not in GK aortas. These results demonstrate that the UII-induced contraction gradually decreased with aging in Wistar rats and was preserved in type 2 diabetes. Although alterations of UII-induced contractions during aging and type 2 diabetes may be associated with kinase activities (MAPKs or Rho kinase) or receptor profiles, further investigations are necessary to clarify the mechanisms.

Plasma urotensin-2 level and Thr21Met but not Ser89Asn polymorphisms of the urotensin-2 gene are associated with migraines

Background

Urotensin-II (U-II) is a peptide recognized by its potent vasoconstrictor activity in many vascular events, however the role of urotensin-II in migraine has not been considered yet. The molecular mechanisms and genetics of migraine have not been fully clarified yet, but it is well-known that vascular changes considerably contribute in pathophysiology of migraine and also its complications. The aim of this study was to analyze the plasma U-II levels along with genotype distributions and allele frequencies for UTS2 Thr21Met and Ser89Asn polymorphisms among the patients with migraine without aura (MWoA).

Methods

One hundred eighty-six patients with MWoA and 171 healthy individuals were included in this study. Plasma U-II levels were measured in attack free period. The genotype and allele frequencies for the Thr21Met (T21M) and Ser89Asn (S89N) polymorphisms in the UTS2 gene were analyzed.

Results

Plasma U-II levels were significantly higher in MWoA patients (p = 0.002). We detected a significant association between the T21M polymorphism in the UTS2 gene and migraine (53.8 % in patients, 40.4 % in controls, p = 0.035), but not with S89N polymorphism (p = 0.620). A significant relationship was found between U-II levels and MIDAS score (β = 0.508, p = 0.001).

Conclusion

Our study suggests that U-II may play a role in migraine pathogenesis; also Thr21Met polymorphism was associated with the risk of migraine disease. Further studies are needed for considering the role of U-II in migraine pathophysiology and for deciding if UTS2 gene may be a novel candidate gene in migraine cases.

Urotensin-II-Mediated Reactive Oxygen Species Generation via NADPH Oxidase Pathway Contributes to Hepatic Oval Cell Proliferation

Urotensin II (UII), a somatostatin-like cyclic peptide, is involved in tumor progression due to its mitogenic effect. Our previous study demonstrated that UII and its receptor UT were up-regulated in human hepatocellular carcinoma (HCC), and exogenous UII promoted proliferation of human hepatoma cell line BEL-7402. Hepatic progenitor cell (HPCs) are considered to be one of the origins of liver cancer cells, but their relationship with UII remains unclear. In this work, we aimed to investigate the effect of UII on ROS generation in HPCs and the mechanisms of UII-induced ROS in promoting cell proliferation. Human HCC samples were used to examine ROS level and expression of NADPH oxidase. Hepatic oval cell line WB-F344 was utilized to investigate the underlying mechanisms. ROS level was detected by dihydroethidium (DHE) or 2’, 7’-dichlorofluorescein diacetate (DCF-DA) fluorescent probe. For HCC samples, ROS level and expression of NADPH oxidase were significantly up-regulated. In vitro, UII also increased ROS generation and expression of NADPH oxidase in WB-F344 cells. NADPH oxidase inhibitor apocynin pretreatment partially abolished UII-increased phosphorylation of PI3K/Akt and ERK, expression of cyclin E/cyclin-dependent kinase 2. Cell cycle was then analyzed by flow cytometry and UII-elevated S phase proportion was inhibited by apocynin pretreatment. Finally, bromodeoxyuridine (Brdu) incorporation assay showed that apocynin partially abolished UII induced cell proliferation. In conclusion, this study indicates that UII-increased ROS production via the NADPH oxidase pathway is partially associated with activation of the PI3K/Akt and ERK cascades, accelerates G1/S transition, and contributes to cell proliferation. These results showed that UII plays an important role in growth of HPCs, which provides novel evidence for the involvement of HPCs in the formation and pathogenesis of HCC.

International Union of Basic and Clinical Pharmacology. XCII. Urotensin II, urotensin II-related peptide, and their receptor: from structure to function

Urotensin II (UII) is a cyclic neuropeptide that was first isolated from the urophysis of teleost fish on the basis of its ability to contract the hindgut. Subsequently, UII was characterized in tetrapods including humans. Phylogenetic studies and synteny analysis indicate that UII and its paralogous peptide urotensin II-related peptide (URP) belong to the somatostatin/cortistatin superfamily. In mammals, the UII and URP genes are primarily expressed in cholinergic neurons of the brainstem and spinal cord. UII and URP mRNAs are also present in various organs notably in the cardiovascular, renal, and endocrine systems. UII and URP activate a common G protein-coupled receptor, called UT, that exhibits relatively high sequence identity with somatostatin, opioid, and galanin receptors. The UT gene is widely expressed in the central nervous system (CNS) and in peripheral tissues including the retina, heart, vascular bed, lung, kidney, adrenal medulla, and skeletal muscle. Structure-activity relationship studies and NMR conformational analysis have led to the rational design of a number of peptidic and nonpeptidic UT agonists and antagonists. Consistent with the wide distribution of UT, UII has now been shown to exert a large array of biologic activities, in particular in the CNS, the cardiovascular system, and the kidney. Here, we review the current knowledge concerning the pleiotropic actions of UII and discusses the possible use of antagonists for future therapeutic applications.

Urotensin-II level and its association with oxidative stress in early diabetic nephropathy

OBJECTIVE

Diabetic nephropathy is the most common cause of end stage renal failure. Early treatment of diabetic nephropathy depends on understanding the underlying mechanisms of the disease. In this study we investigated the role of U-II in early nephropathy and ıts association with oxidative stress, paraoxonase (PON)-1 and arylesterase.

RESEARCH DESIGN AND METHODS

Twenty-three diabetic patients with microalbuminuria, 23 diabetic patients with normoalbuminuria and 25 healthy individuals were enrolled in the study. Serum total antioxidant status (TAS), total oxidant status (TOS), PON-1, arylesterase, and urotensin-II (U-II) levels were measured. Oxidative stress index (OSI) percent ratio of TOS to TAS level was accepted as OSI.

RESULTS

Serum U-II levels were higher in the microalbuminuric diabetes group compared to the normoalbuminuric diabetic group and the healthy control group (p=0.009 and p=0.0001, respectively). Normoalbuminuric diabetic group's U-II levels were significantly higher compared to those of the healthy control group (p=0.0001). Correlation analysis yielded that plasma U-II levels are negatively correlated to TAS, arylesterase, and PON-1 levels (r=-0.395, p=0.001; r=-0.291, p=0.014; and r=-0.279, p=0.018, respectively) and that they had a positive correlation with OSI levels (r=0.312, p=0.008). These associations were confirmed in the multiple regression analysis. The results of multiple logistic regression analysis showed that oxidative stress is important in the development of microalbuminuria.

CONCLUSION

The data of this study reveal that increased serum U-II has a role in the development of diabetic nephropathy. This effect of U-II may be related to high levels oxidative stress parameters.

Up-regulation of urotensin II and its receptor contributes to human hepatocellular carcinoma growth via activation of the PKC, ERK1/2, and p38 MAPK signaling pathways

Urotensin II (UII) and its receptor (UTR) have mitogenic effects on tumor growth. Our previous study demonstrated that the UII/UTR system is up-regulated in dithyinitrosamine-induced precancerous rat liver lesions. However, its role in human hepatocellular carcinoma remains unknown. In this study, the mRNA and protein expression of UII and its receptor (UTR) in human hepatocellular carcinoma samples and in the BEL-7402 human hepatoma cell line were evaluated. In addition, the effect of exogenous UII on the pathways that regulate proliferation in BEL-7402 cells in vitro were determined. Liver sections were subjected to immunohistochemical staining. mRNA expression was detected by real-time polymerase chain reaction analysis, and protein levels were evaluated by western blotting. Proliferating cells were detected by BrdU incorporation. The expression of UII/UT mRNA and protein significantly increased in human hepatocellular carcinoma samples, and in BEL-7402 cells. Administration with UII increased the phosphorylation of protein kinase C (PKC), extracellular signal-regulated kinase (ERK1/2) and p38 mitogen-activated protein kinases (p38 MAPK). Furthermore, GF109203x, PD184352, and SB203580 partially abolished UII-induced proliferation of BEL-7402 cells. These results provide the first evidence that up-regulation of the UII/UT system may enhance proliferation of the human hepatoma cell line at least in part via PKC, ERK1/2, and p38 MAPK signaling pathways, and may provide novel therapeutic targets for inhibiting human hepatocellular carcinoma.

New molecule in the etiology of schizophrenia: urotensin II

AIMS

Urotensin II (U-II) is a cyclic peptide that was first isolated from the caudal neurosecretory system of goby fish. U-II receptors were detected in the vascular endothelium, brain and kidney cortex. Urotensin is by far the most powerful vasoconstrictor identified. U-II molecules were previously isolated from the brain of rats and were shown to have an impact on rat behavior. The aim of the present study was to measure the level of U-II molecule in schizophrenia patients and to investigate whether the U-II level is associated with the etiology of schizophrenia.

METHODS

Forty schizophrenia patients who were followed at Gaziantep University Faculty of Medicine Department of Psychiatry Psychotic Disorders Unit and 40 healthy volunteers were enrolled in this study. Blood samples were taken from the antecubital vein after 12-h fasting. U-II level was measured on ELISA.

RESULTS

The U-II level in schizophrenia patients was significantly higher than in the control group. U-II level was not different with regard to gender in either group. U-II level was not different between subgroups of schizophrenia. No significant correlation was found between U-II level, Positive and Negative Syndrome Scale and Clinical Global Impression-Severity scale scores.

CONCLUSION

U-II level was higher in schizophrenia patients, indicating that U-II level may be related to the etiology of the disease.

UII and UT in grouper: cloning and effects on the transcription of hormones related to growth control

Urotensin II (UII) is a cyclic peptide that was originally extracted from the caudal neurosecretory system (CNSS) of fish. UII is well known to exhibit cardiovascular, ventilatory, and motor effects in vertebrates. Studies have reported that UII exerts mitogenic effects and can act as an autocrine/paracrine growth factor in mammals. However, similar information in fish is limited. In this study, the full-length cDNAs of UII and its receptor (UT) were cloned and characterized in the orange-spotted grouper. UII and UT were expressed ubiquitously in various tissues in grouper, and particularly high levels were observed in the CNSS, CNS, and ovary. A functional study showed that UT was coupled with intracellular Ca2+ mobilization in HEK293 cells. Studies carried out using i.p. injections of UII in grouper showed the following: i) in the hypothalamus, UII can significantly stimulate the mRNA expression of ghrh and simultaneously inhibit the mRNA expression of somatostatin 1 (ss1) and ss2 3 h after injection; ii) in the pituitary, UII also significantly induced the mRNA expression of gh 6 and 12  h after injection; and iii) in the liver, the mRNA expression levels of ghr1/ghr2 and igf1/igf2 were markedly increased 12 and 3  h after the i.p. injection of UII respectively. These results collectively indicate that the UII/UT system may play a role in the promotion of the growth of the orange-spotted grouper.

Urotensin II and the kidney

PURPOSE OF REVIEW

Urotensin II (UTS2), the most potent vasoconstrictor identified thus far, is an undecapeptide hormone with a structure that is highly conserved through mammalian phylogeny. In spite of its broad expression across the invertebrate and vertebrate world, the precise role of UTS2 in physiology and disease is still unknown. The first description of human UTS2 and its receptor brought initial promise of a potential therapeutic target for progressive renal disease, with vasoconstrictive and profibrotic actions within an autocrine and paracrine system and local renal generation that was upregulated with renal pathology.

RECENT FINDINGS

However, the last decade has not brought the successful development of new treatments first hoped for, with one small human clinical trial bearing negative results. What has become apparent is that the spectrum of actions of UTS2 is broad and often paradoxical. This ancient hormone has both vasoconstrictor and vasodilatory actions, has both profibrotic and antiapoptotic activity, as well as actions which are highly contextual on the particular vascular bed studied and on the presence or absence of superimposed disease state.

SUMMARY

With current development of newer UTS2 antagonists attempting to more closely replicate the ligand-receptor kinetics of UTS2 and its receptor, the focus on potential clinical applications of UTS2 inhibition has moved away from the kidney to the treatment of chronic lung and cardiovascular diseases.

Urotensin II receptor antagonism confers vasoprotective effects in diabetes associated atherosclerosis: studies in humans and in a mouse model of diabetes

AIMS/HYPOTHESIS

The small, highly conserved vasoactive peptide urotensin II (UII) is upregulated in atherosclerosis. However, its effects in diabetes-associated atherosclerosis have not been assessed.

METHODS

Endothelial cells were grown in normal- and high-glucose (5 and 25 mmol/l) media with and without UII (10⁻⁸ mol/l) and/or the UII receptor antagonist, SB-657510 (10⁻⁸ mol/l). Apoe knockout (KO) mice with or without streptozotocin-induced diabetes were treated with or without SB-657510 (30 mg kg⁻¹ day⁻¹; n = 20 per group) and followed for 20 weeks. Carotid endarterectomy specimens from diabetic and non-diabetic humans were also evaluated.

RESULTS

In high (but not normal) glucose medium, UII significantly increased CCL2 (encodes macrophage chemoattractant protein 1 [MCP-1]) gene expression (human aortic endothelial cells) and increased monocyte adhesion (HUVECs). UII receptor antagonism in diabetic Apoe KO mice significantly attenuated diabetes-associated atherosclerosis and aortic staining for MCP-1, F4/80 (macrophage marker), cyclooxygenase-2, nitrotyrosine and UII. UII staining was significantly increased in carotid endarterectomies from diabetic compared with non-diabetic individuals, as was staining for MCP-1.

CONCLUSIONS/INTERPRETATION

This is the first report to demonstrate that UII is increased in diabetes-associated atherosclerosis in humans and rodents. Diabetes-associated plaque development was attenuated by UII receptor antagonism in the experimental setting. Thus UII may represent a novel therapeutic target in the treatment of diabetes-associated atherosclerosis.

Urotensin-II: More Than a Mediator for Kidney

Human urotensin-II (hU-II) is one of the most potent vasoconstrictors in mammals. Although both hU-II and its receptor, GPR14, are detected in several tissues, kidney is a major source of U-II in humans. Recent studies suggest that U-II may have a possible autocrine/paracrine functions in kidney and may be an important target molecule in studying renal pathophysiology. It has several effects on tubular transport and probably has active role in renal hemodynamics. Although it is an important peptide in renal physiology, certain diseases, such as hypertension and glomerulonephritis, may alter the expression of U-II. As might be expected, oxidative stress, mediators, and inflammation are like a devil's triangle in kidney diseases, mostly they induce each other. Since there is a complex relationship between U-II and oxidative stress, and other mediators, such as transforming growth factor β1 and angiotensin II, U-II is more than a mediator in glomerular diseases. Although it is an ancient peptide, known for 31 years, it looks like that U-II will continue to give new messages as well as raising more questions as research on it increases. In this paper, we mainly discuss the possible role of U-II on renal physiology and its effect on kidney diseases.

Novel pathways and therapies in experimental diabetic atherosclerosis

Diabetic subjects are at a greater risk of developing major vascular complications due to abnormalities pertinent to the diabetic milieu. Current treatment options achieve significant improvements in glucose levels and blood pressure control, but do not necessarily prevent or retard diabetes-mediated macrovascular disease. In this review, we highlight several pathways that are increasingly being appreciated as playing a significant role in diabetic vascular injury. We focus particularly on the advanced glycation end product/receptor for advanced glycation end product (AGE/RAGE) axis and its interplay with the nuclear protein HMGB1. We discuss evidence implicating a significant role for the renin-angiotensin system, urotensin II and PPAR, as well as the importance of proinflammatory mediators and oxidative stress in cardiovascular complications. The specific targeting of these pathways may lead to novel therapies to reduce the burden of diabetic vascular complications.

Influence of Ca2+ and pH on the folding of the prourotensin II precursor

Proper folding is a crucial step for the trafficking of proteins through the secretory pathway. We hypothesized that the secretory granules of endocrine cells provide optimal folding conditions of prohormone precursors for cleavage. Here, using circular dichroism and in vitro processing on purified prourotensin II (ProUII), we show that the precursor undergoes pH- and Ca(2+)-dependent conformational and stability changes. ProUII has a stable tertiary structure at pH 5.5 in presence of Ca(2+) and is correctly cleaved in these conditions by prohormone convertases. Taken together, our results support the notion that precursors may need to be optimally folded in the lumen of secretory granules for their processing.

Elevated expression of urotensin II and its receptor in diethylnitrosamine-mediated precancerous lesions in rat liver

Urotensin II (UII) is a somatostatin-like peptide involved in cell proliferation and in tumor biology. To explore the role of liver-derived UII in the pathogenesis of precancerous liver lesions in rat, we investigated the expression of UII and its receptor, UT, in diethylnitrosamine (DEN)-induced precancerous liver lesions and the effects of UII on cell proliferation by hepatic oval cells. Radioimmunoassay, RT-PCR, immunohistochemistry and western blot were used in this study. Compared with untreated controls, rats treated with DEN showed increased UII content by 47.7% in plasma and by 164.9% in liver tissue (all P<0.01). The expression of UII protein and of both UT mRNA and protein was significantly enhanced in the liver of treated rats. Western blot analysis revealed that the expression of phosphorylated protein kinase C (p-PKC) and phosphorylated extracellular signal-regulated kinase (p-ERK1/2) was increased in the liver of treated animals. Treatment with UII (10(-10)-10(-6)M) for 24h significantly increased number of cultured hepatic oval cells (at 10(-9)-10(-8)M). However, during the pre-incubation with calphostin C (inhibitor of PKC) or PD98059 (inhibitor of MEK), the proliferation was decreased by 40.1% and 25.4% respectively (both P<0.05). In DEN-induced precancerous liver lesions, the UII/UT system was up-regulated, which may contribute to the pathogenesis of liver cancer through a PKC- or ERK1/2-dependent pro-mitogenic pathway in an autocrine/paracrine manner.

Urotensin II induction of adult cardiomyocytes hypertrophy involves the Akt/GSK-3beta signaling pathway

Urotensin II (UII) a potent vasoactive peptide is upregulated in the failing heart and promotes cardiomyocytes hypertrophy, in particular through mitogen-activated protein kinases. However, the regulation by UII of GSK-3beta, a recognized pivotal signaling element of cardiac hypertrophy has not yet been documented. We therefore investigated in adult cardiomyocytes, if UII phosphorylates GSK-3beta and Akt, one of its upstream regulators and stabilizes beta-catenin, a GSK-3beta dependent nuclear transcriptional co-activator. Primary cultures of adult rat cardiomyocytes were stimulated for 48h with UII. Cell size and protein/DNA contents were determined. Phosphorylated and total forms of Akt, GSK-3beta and the total amount of beta-catenin were quantified by western blot. The responses of cardiomyocytes to UII were also evaluated after pretreatment with the chemical phosphatidyl-inositol-3-kinase inhibitor, LY294002, and urantide, a competitive UII receptor antagonist. UII increased cell size and the protein/DNA ratio, consistent with a hypertrophic response. UII also increased phosphorylation of Akt and its downstream target GSK-3beta. beta-Catenin protein levels were increased. All of these effects of UII were prevented by LY294002, and urantide. The UII-induced adult cardiomyocytes hypertrophy involves the Akt/GSK-3beta signaling pathways and is accompanied by the stabilization of the beta-catenin. All these effects are abolished by competitive inhibition of the UII receptor, consistent with new therapeutic perspectives for heart failure treatment.

Urotensin-II as an angiogenic factor

Angiogenesis, the process through which new blood vessels arise from pre-existing ones, is regulated by numerous "classic" factors and other "nonclassic" regulators of angiogenesis. Among these latter urotensin-II is a cyclic 11-amino acid (human) or 15-amino acid (rodent) peptide, originally isolated from the fish urophysis, which exerts a potent systemic vasoconstrictor and hypertensive effect. This review article summarizes the literature data concerning the involvement of urotensin-II in angiogenesis.

Chronic urotensin-II infusion induces diastolic dysfunction and enhances collagen production in rats

The vasoactive peptide urotensin-II (U-II) is likely to play a key causal role in cardiac remodeling that ultimately leads to heart failure. Its contribution, specifically to the development of diastolic dysfunction and the downstream intracellular signaling, however, remains unresolved. This study interrogates the effect of chronic U-II infusion in normal rats on cardiac structure and function. The contribution of Rho kinase (ROCK) signaling to these pathophysiological changes is evaluated in cell culture studies. Chronic high-dose U-II infusion over 4 wk significantly impaired diastolic function in rats on echocardiography-derived Doppler indexes, including E-wave deceleration time (vehicle 56.7 +/- 3.3 ms, U-II 118.0 +/- 21.5 ms; P < 0.01) and mitral valve annulus peak early/late diastolic tissue velocity (vehicle 2.01 +/- 0.19 ms, U-II 1.04 +/- 0.25 ms; P < 0.01). A lower dose of U-II infusion (1 nmol.kg(-1).h(-1)) yielded comparable changes. Diastolic dysfunction was accompanied by molecular [significant increases in procollagen-alpha(1)(I) gene expression on real-time PCR] and morphological (increases in total collagen, P < 0.05, and collagen type-I protein deposition, P < 0.001) evidence of left ventricular (LV) fibrosis following high-dose U-II infusion. The ROCK inhibitor GSK-576371 (10(-7) to 10(-5) M) elicited concentration-dependent inhibition of U-II (10(-7) M)-stimulated cardiac fibroblast collagen synthesis and cardiac myocyte protein synthesis. Chronic U-II infusion causes diastolic dysfunction, caused by fibrosis of the LV. The in vitro data suggest that this may be in part occurring via a ROCK-dependent pathway.

Effect of the urotensin-II receptor antagonist palosuran on secretion of and sensitivity to insulin in patients with Type 2 diabetes mellitus

AIMS

To investigate the effects of palosuran, a nonpeptidic, potent and selective antagonist of the urotensin-II receptor, on insulin and glucose regulation in 20 diet-treated patients with Type 2 diabetes mellitus in a double-blind, placebo-controlled, randomized, crossover, proof-of-concept study.

METHODS

After 4 weeks' oral treatment with 125 mg palosuran or placebo b.i.d.,effects on insulin secretion and sensitivity and blood glucose levels were assessed by means of a hyperglycaemic glucose clamp, meal tolerance test, homeostasis model assessment-insulin resistance score, and daily self-monitoring of blood glucose. Plasma concentrations of palosuran were determined for 12 h on the last day of intake.

RESULTS

Palosuran did not affect second-phase insulin response (primary end-point) during the hyperglycaemic glucose clamp in comparison with placebo [paired difference of -1.8 microU ml(-1), 95% confidence interval (CI) -7.8, 4.2]. Likewise, no effects of palosuran were detected on the first-phase insulin response, or on insulin secretion and blood glucose levels during the meal tolerance test or on homeostasis model assessment-insulin resistance score. No clinically significant effects on daily blood glucose profiles were observed during the study. Geometric mean C(max) and AUC(tau) (95% CI) and median t(max) (range) in this patient population were 180 ng ml(-1) (125, 260), 581 ng.h ml(-1) (422, 800) and 3.0 h (0.67, 4.3), respectively.

CONCLUSIONS

The results of this study indicate that antagonism of the urotensin-II system does not influence insulin secretion or sensitivity or daily blood glucose levels in diet-treated patients with Type 2 diabetes.

Desensitisation of native and recombinant human urotensin-II receptors

Human urotensin-II (U-II) is an 11-amino-acid cyclic peptide that activates a G(q)-coupled receptor named UT. Little is known about the desensitisation profile of this receptor as peptide binding is essentially irreversible. In the present study, we have examined the effects of U-II and carbachol on Ca(2+) signalling in SJCRH30 rhabdomyosarcoma (receptor density, B(max) approximately 0.1 pmol/mg protein) and human embroynic kidney (HEK)(hUT) (B(max) approximately 1.4 pmol/mg protein) cells expressing native and recombinant UT, respectively. In SJCRH30, HEK(hUT) and human peripheral blood mononuclear cells induced to express native UT by treatment with 2 microg/ml lipopolysaccharide (LPS), we have measured the effects of U-II treatment on UT mRNA. In SJCRH30 cells, primary stimulation with carbachol (250 microM) did not affect a secondary challenge with U-II (1 microM) and primary challenge with U-II did not affect a secondary challenge with carbachol. In contrast, in HEK(hUT) cells, primary stimulation with carbachol (250 microM) reduced a secondary challenge to U-II (1 microM) by 84% and primary challenge with U-II reduced a secondary challenge to carbachol by 76%. Pre-treatment of SJCRH30 cells with U-II reduced UT mRNA after 6 h and this returned to basal after 24 h. In recombinant HEK(hUT) cells, UT mRNA expression increased following a 6 h treatment with 1 microM U-II. U-II treatment of naïve un-stimulated peripheral blood mononuclear cells was without effect. However, when UT expression is up-regulated following 15 h of LPS treatment, a 6 h U-II challenge reduced UT mRNA by 66%. In summary, we report differences in the desensitisation profiles of native and recombinant U-II receptors. Design and interpretation of functional experiments are hampered by irreversibility of U-II binding.

Pharmacokinetics and pharmacodynamics of the urotensin-II receptor antagonist palosuran in healthy male subjects

Palosuran is a new potent and specific antagonist of the human urotensin II (U-II) receptor (UT receptor). This entry-into-humans study evaluated the tolerability and safety, pharmacokinetics, and pharmacodynamics of palosuran in a double-blind, placebo-controlled, single ascending-dose design. Oral doses of 5 to 2000 mg were given to 9 sequential groups of 8 healthy young men (6 on active drug, 2 on placebo) each. At regular intervals, tolerability and safety parameters and plasma levels of palosuran and U-II were determined. Urine was collected to determine excretion of sodium, potassium, creatinine, and palosuran. In this study, palosuran was well tolerated. No serious adverse events or dose-related adverse events were reported. No treatment-related pattern was detected for vital signs, clinical laboratory parameters, or electrocardiography parameters. After rapid absorption, palosuran displayed a plasma concentration-time profile characterized by 2 peaks at approximately 1 and 4 hours after drug administration. The apparent terminal elimination half-life was approximately 20 hours. AUC and C(max) values increased proportionally with doses up to 500 mg. Excretion of unchanged palosuran in urine was limited. No consistent effect was found on any of the pharmacodynamic variables measured. The results of this entry-into-humans study warrant further investigation of the therapeutic potential of palosuran.

Structure-activity relationships of urotensin II and URP

Urotensin II (U-II) and urotensin II-related peptide (URP) are the endogenous ligands for the orphan G-protein-coupled receptor GPR14 now renamed UT. At the periphery, U-II and/or URP exert a wide range of biological effects on cardiovascular tissues, airway smooth muscles, kidney and endocrine glands, while central administration of U-II elicits various behavioral and cardiovascular responses. There is also evidence that U-II and/or URP may be involved in a number of pathological conditions including heart failure, atherosclerosis, renal dysfunction and diabetes. Because of the potential involvement of the urotensinergic system in various physiopathological processes, there is need for the rational design of potent and selective ligands for the UT receptor. Structure-activity relationship studies have shown that the minimal sequence required to retain full biological activity is the conserved U-II(4-11) domain, in particular the Cys5 and Cys10 residues involved in the disulfide bridge, and the Phe6, Lys8 and Tyr9 residues. Free alpha-amino group and C-terminal COOH group are not necessary for the biological activity, and modifications of these radicals may even increase the stability of the analogs. Punctual substitution of native amino acids, notably Phe6 and Trp7, by particular residues generates analogs with antagonistic properties. These studies, which provide crucial information regarding the structural and conformational requirements for ligand-receptor interactions, will be of considerable importance for the design of novel UT ligands with increased selectivity, potency and stability, that may eventually lead to the development of innovative drugs.

Immunolocalization of urotensin II and its receptor in human adrenal tumors and attached non-neoplastic adrenal tissues

Urotensin II (UII), first identified from goby urophysis, is a potent vasoactive peptide hormone and an endogenous ligand for an orphan G protein-coupled receptor GPR14, now named urotensin II receptor (UT-R). In addition to its vascular actions, UII has been shown to have mitogenic effects on tumor growth and some regulatory effects on adrenal steroidogenesis. In the present study, we examined expression of UII and UT-R in human adrenal tumors and attached non-neoplastic adrenal tissues by immunohistochemistry. Both UII and UT-R were immunolocalized in tumor cells of all adrenal tumors examined: 8 cases of cortisol-producing adenomas, 8 cases of aldosterone-producing adenomas, 2 cases of non-functioning adenomas, 17 cases of adrenocortical carcinomas, and 8 cases of pheochromocytomas. In attached adrenals, immunoreactivity for UII was detected in medulla, but much weaker in the cortex than in cortical tumors, suggesting that expression of UII was up-regulated in neoplastic adrenocortical tissues. No significant differences were found in the degree of immunoreactivity for UT-R between the tumors and the attached adrenal tissues. The present study showed that both UII and UT-R were expressed in the adrenal tumors and attached non-neoplastic adrenal tissues, and suggests possible roles of UII and UT-R in tumor growth and/or secretory activities of these tumors.

Solution structure of urotensin-II receptor extracellular loop III and characterization of its interaction with urotensin-II

Urotensin-II (U-II) is a vasoactive hormone that acts through a G-protein-coupled receptor named UT. Recently, we have shown, using the surface plasmon resonance technology that human U-II (hU-II) interacts with the hUT(281-300) fragment, a segment containing the extracellular loop III (EC-III) and short extensions of the transmembrane domains VI and VII (TM-VI and TM-VII). To further investigate the interaction of UT receptor with U-II, we have determined the solution structure of hUT(281-300) by high-resolution NMR and molecular modeling and we have examined, also using NMR, the binding with hU-II at residue level. In the presence of dodecylphosphocholine micelles, hUT(281-300) exhibited a type III beta-turn (Q285-L288), followed by an -helical structure (A289-L299), the latter including a stretch of transmembrane helix VII. Upon addition of hU-II, significant chemical shift perturbations were observed for residues located just on the N-terminal side of the beta-turn (end of TM-VI/beginning of EC-III) and on one face of the -helix (end of EC-III/beginning of TM-VII). These data, in conjunction with intermolecular NOEs, suggest that the initiation site of EC-III, as well as the upstream portion of helix VII, would be involved in agonist binding and allow to propose points of interaction in the ligand-receptor complex.

Biological properties and functional determinants of the urotensin II receptor

The urotensin II receptor (UT) is a member of the G protein-coupled receptor (GPCR) family and binds the cyclic undecapeptide urotensin II (U-II) as well as the octapeptide urotensin II-related peptide (URP). The active UT mediates pleiotropic effects through various signal transduction pathways, including coupling to G proteins and activating the mitogen-activated protein kinase pathway. Several highly conserved residues and motifs of class A GPCRs that are important for activity are found in UT. This review highlights some of the putative roles of these motifs in the binding, activation and desensitization of UT.

Liberation of urotensin II from the teleost urophysis: an historical overview

During the past 20 years, urotensin II (UII) has progressed from being a peptide synthesized only in the urophysis of the caudal neurosecretory system of teleost fish to being considered an important physiological regulator in mammals with implications for the pathogenesis of a range of human cardiovascular and renal diseases. The "liberation" of UII from the urophysis was a gradual process and involved the sequential realization that (a) UII is present not only in the urophysis but also in the central nervous systems (CNS) of teleosts, (b) UII peptides, similar in structure to the urophysial peptides, are present in the diffuse caudal neurosecretory systems and/or CNS of species less evolutionarily advanced than teleosts, including Agnatha, thereby showing that UII is a phylogenetically ancient peptide, (c) UII is present in the brain and spinal cord of a tetrapod, the green frog Rana ridibunda, and (d) the UII gene and its specific receptor (GPR14/UT) are expressed in the CNS and certain peripheral tissues of mammals, including the human. The discovery that the genomes of mammals contain an additional gene encoding a UII-related peptide (URP) and the availability of highly effective peptide and non-peptide antagonists to investigate the role of UII in human physiology and pathophysiology ensure that the peptide will remain "center stage" for several years to come.

Form-deprivation myopia in chick induces limited changes in retinal gene expression

PURPOSE

Evidence has implicated the retina as a principal controller of refractive development. In the present study, the retinal transcriptome was analyzed to identify alterations in gene expression and potential signaling pathways involved in form-deprivation myopia of the chick.

METHODS

One-week-old white Leghorn chicks wore a unilateral image-degrading goggle for 6 hours or 3 days (n = 6 at each time). Total RNA from the retina/(retinal pigment epithelium) was used for expression profiling with chicken gene microarrays (Chicken GeneChips; Affymetrix, Santa Clara, CA). To identify gene expression level differences between goggled and contralateral nongoggled eyes, normalized microarray signal intensities were analyzed by the significance analysis of microarrays (SAM) approach. Differentially expressed genes were validated by real-time quantitative reverse transcription-polymerase chain reaction (qPCR) in independent biological replicates.

RESULTS

Small changes were detected in differentially expressed genes in form-deprived eyes. In chickens that had 6 hours of goggle wear, downregulation of bone morphogenetic protein 2 and connective tissue growth factor was validated. In those with 3 days of goggle wear, downregulation of bone morphogenetic protein 2, vasoactive intestinal peptide, preopro-urotensin II-related peptide and mitogen-activated protein kinase phosphatase 2 was validated, and upregulation of endothelin receptor type B and interleukin-18 was validated.

CONCLUSIONS

Form-deprivation myopia, in its early stages, is associated with only minimal changes in retinal gene expression at the level of the transcriptome. While the list of validated genes is short, each merits further study for potential involvement in the signaling cascade mediating myopia development.

Role of urotensin II and its receptor in health and disease

Urotensin II (U-II) is currently the most potent vasoconstrictor identified. This action is brought about via activation of a G(q/11)-protein coupled receptor (UT receptor). U-II activation of the UT receptor increases inositol phosphate turnover and intracellular Ca(2+). In addition to producing vasoconstriction, dilation and ionotropic effects have also been described. There is considerable variation in the responsiveness of particular vascular beds from the same and different species, including humans. Receptors for U-II are located peripherally on vascular smooth muscle (contractile responses) and endothelial cells (dilatory responses via nitric oxide). In humans, plasma U-II is elevated in heart failure, renal failure, liver disease, and diabetes. Iontophoresis of U-II in healthy volunteers produces vasodilation (of the forearm) while in patients with heart failure or hypertension a constriction is observed. To date there is only one clinical study using a UT receptor antagonist (palosuran) in diabetic patients with macroalbuminuria. This antagonist reduced albumin excretion, probably by increasing renal blood flow. Studies in other disease conditions are eagerly awaited. In summary, the U-II / UT receptor system has clinical potential, and for the anesthesiologist, this novel peptide-receptor system may be of use in the intensive care unit.

Photolabelling the urotensin II receptor reveals distinct agonist- and partial-agonist-binding sites

The mechanism by which GPCRs (G-protein-coupled receptors) undergo activation is believed to involve conformational changes following agonist binding. We have used photoaffinity labelling to identify domains within GPCRs that make contact with various photoreactive ligands in order to better understand the activation mechanism. Here, a series of four agonist {[Bpa1]U-II (Bpa is p-benzoyl-L-phenylalanine), [Bpa2]U-II, [Bpa3]U-II and [Bpa4]U-II} and three partial agonist {[Bpa1Pen5D-Trp7Orn8]U-II (Pen is penicillamine), [Bpa2Pen5D-Trp7Orn8]U-II and [Pen5Bpa6D-Trp7Orn8]U-II} photoreactive urotensin II (U-II) analogues were used to identify ligand-binding sites on the UT receptor (U-II receptor). All peptides bound the UT receptor expressed in COS-7 cells with high affinity (Kd of 0.3-17.7 nM). Proteolytic mapping and mutational analysis led to the identification of Met288 of the third extracellular loop of the UT receptor as a binding site for all four agonist peptides. Both partial agonists containing the photoreactive group in positions 1 and 2 also cross-linked to Met288. We found that photolabelling with the partial agonist containing the photoreactive group in position 6 led to the detection of transmembrane domain 5 as a binding site for that ligand. Interestingly, this differs from Met184/Met185 of the fourth transmembrane domain that had been identified previously as a contact site for the full agonist [Bpa6]U-II. These results enable us to better map the binding pocket of the UT receptor. Moreover, the data also suggest that, although structurally related agonists or partial agonists may dock in the same general binding pocket, conformational changes induced by various states of activation may result in slight differences in spatial proximity within the cyclic portion of U-II analogues.

Structure-activity relationships of a novel series of urotensin II analogues: identification of a urotensin II antagonist

Urotensin II (U-II) is a potent vasoconstrictor peptide which has been identified as the endogenous ligand for the orphan G protein-coupled receptor GPR14 now renamed UT receptor. As the C-terminal cyclic hexapeptide of U-II (U-II(4-11), H-Asp-Cys-Phe-Trp-Lys-Tyr-Cys-Val-OH) possesses full biological activity, we have synthesized a series of U-II(4-11) analogues and measured their binding affinity on hGPR14-transfected CHO cells and their contractile activity on de-endothelialized rat aortic rings. The data indicate that a free amino group and a functionalized side-chain at the N-terminal extremity of the peptide are not required for biological activity. In addition, the minimal chemical requirement at position 9 of U-II(4-11) is the presence of an aromatic moiety. Most importantly, replacement of the Phe6 residue by cyclohexyl-Ala (Cha) led to an analogue, [Cha6]U-II(4-11), that was devoid of agonistic activity but was able to dose-dependently suppress the vasoconstrictor effect of U-II on rat aortic rings. These new pharmacological data, by providing further information regarding the structure-activity relationships of U-II analogues, should prove useful for the rational design of potent and nonpeptidic UT receptor agonists and antagonists.

Does cigarette smoking increase plasma urotensin II concentrations?

OBJECTIVE

Human urotensin II (UII) acts on the urotensin (UT) receptor and is the most potent mammalian vasoconstrictor identified to date. The role of UII in human cardiovascular regulation remains unclear, and the results of plasma measurements have been conflicting, perhaps because different measurement techniques have been used. The effects of cigarette smoking on plasma UII concentrations are unknown. The primary aim of our study was to demonstrate whether cigarette smoking had any effect on plasma UII concentrations in otherwise healthy volunteers. Our secondary aim was to compare the results obtained from assaying simultaneously using both radioimmunoassay (RIA) and immunoluminometric assay (ILMA).

METHODS

Blood was taken from 20 healthy male non-smokers and 20 healthy male cigarette smokers. Plasma was separated and stored at -70 degrees C. Samples were batch analysed simultaneously for UII using RIA and ILMA.

RESULTS

Median (range) plasma UII concentrations were lower in non-smokers [1.67 (1.0-2.27) pg ml(-1)] compared to smokers [2.62 (1.87-3.46) pg ml(-1)] (P = 0.03) measured using RIA. Those who had smoked a cigarette in the 10 min before sampling had greater concentrations of UII [3.10 (1.87-4.60) pg ml(-1)] compared to controls (P = 0.01). Plasma UII concentrations determined by ILMA were consistently low with no differences between groups.

CONCLUSION

The data obtained by RIA show that smoking may increase plasma concentrations of UII with a more pronounced increase when a cigarette has been smoked recently. There was a complete lack of correlation between RIA and ILMA for the whole data set, which suggests that some of the variability in plasma UII reported in the literature may result from differences between assays.

Cardiovascular effects of native and non-native urotensin II and urotensin II-related peptide on rat and salmon hearts

Urotensin II (UII) was first discovered in the urophyses of goby fish and later identified in mammals, while urotensin II-related peptide (URP) was recently isolated from rat brain. We studied the effects of UII on isolated heart preparations of Chinook salmon and Sprague-Dawley rats. Native rat UII caused potent and sustained, dose-dependent dilation of the coronary arteries in the rat, whereas non-native UII (human and trout UII) showed attenuated vasodilation. Rat URP dilated rat coronary arteries, with 10-fold less potency compared with rUII. In salmon, native trout UII caused sustained dilation of the coronary arteries, while rat UII and URP caused significant constriction. Nomega-nitro-(l)-arginine methyl (l-NAME) and indomethacin significantly attenuated the URP and rat UII-induced vasodilation in the rat heart. We conclude that UII is a coronary vasodilator, an action that is species form specific. We also provide the first evidence for cardiac actions of URP, possibly via mechanisms common with UII.

Exercise urotensin II dynamics in myocardial infarction survivors with and without hypertension

BACKGROUND

Hypertension is diagnosed in approximately 50% of patients with acute myocardial infarction. Urotensin II (U-II) - a potent vasoactive peptide shown to be elevated in hypertensive subjects, can contribute to negative myocardial remodelling and development of left ventricular failure. Data concerning U-II activity under exercise conditions and its influence on blood pressure in patients after myocardial infarction is scant. Therefore we sought to determine U-II dynamics during exercise in myocardial infarction survivors with and without hypertension.

METHODS

Forty patients with acute myocardial infarction treated with successful primary coronary angioplasty, after four weeks of uneventful and symptom-free period following initial hospitalization underwent treadmill exercise test. U-II plasma concentration was measured before and shortly after the exercise.

RESULTS

Hypertension was diagnosed in 17 (42.5%) patients. We found no significant differences between normotensive and hypertensive subjects except higher smoking rate and lower calcium channel blockers prescription in normotensive patients. Both systolic and diastolic blood pressure were comparable between study groups before exercise. After exercise we observed higher systolic blood pressure in hypertensive subjects (169.06 +/- 30.23 vs. 150.0 +/- 18.97 mm Hg; p < 0.05). U-II concentration showed no significant difference in pretest sampling (54.93 +/- 38.11 vs. 73.97 +/- 48.52 ng/ml; p = NS). After exercise we noted significantly higher peptide level in hypertensive patients (63.32 +/- 36.11 vs. 98.03 +/- 40.47 ng/ml; p = 0.01).

CONCLUSIONS

The present study is the first one to show differences in U-II concentration exercise dynamics in hypertensive and normotensive myocardial infarction survivors. It sheds additional light on hypertension pathophysiology in myocardial infarction patients, and thus identifies a novel, potentially relevant, target for future therapeutic interventions.

Novel Potent and Efficacious Nonpeptidic Urotensin II Receptor Agonists

Six different series of nonpeptidic urotensin II receptor agonists have been synthesized and evaluated for their agonistic activity in a cell-based assay (R-SAT). The compounds are ring-opened analogues of the isochromanone-based agonist AC-7954 with different functionalities constituting the linker between the two aromatic ring moieties. Several of the compounds are highly potent and efficacious, with N-[1-(4-chlorophenyl)-3-(dimethylamino)-propyl]-4-phenylbenzamide oxalate (5d) being the most potent. The pure enantiomers of 5d were obtained from the corresponding diastereomeric amides. It was shown by a combination of X-ray crystallography and chemical correlation that the activity resides in the S-enantiomer of 5d (pEC(50) 7.49).