Regulation of production and secretion of adrenomedullin in the cardiovascular system

Comparison of the antihypertensive effects of folic acid and resveratrol in spontaneously hypertensive rats combined with hyperhomocysteinemia

Objectives

Studies have found that both folic acid and resveratrol have potential benefits in reducing complications of hypertension. The aim of this study was to compare the effects of resveratrol and folic acid on blood pressure in spontaneously hypertensive rats combined with hyperhomocystinemia, and to explore their potential mechanisms.

Methods

Twenty-four male specific pathogen free (SPF) SPF grade spontaneously hypertensive rats were randomly divided into four groups: the SHR group, the hypertension combined with hyperhomocystinemia group (SHR + HHcy), the folic acid intervention group (SHR + HHcy + FA), and the resveratrol intervention group (SHR + HHcy + Res). The rat model of hypertension combined with hyperhomocystinemia was constructed, and then folic acid or resveratrol were given by gavage. Rat tail artery blood pressure, serum homocysteine concentration, superoxide dismutase activity, malondialdehyde levels, and mRNA transcription and protein expression of endothelial nitric oxide synthase and angiotensin II were detected.

Result

Compared with the SHR group, the SHR + HHcy group significantly increased hyperhomocystinemia and malondialdehyde levels, and inhibited superoxide dismutase activity and endothelial nitric oxide synthase expression. Compared with the SHR + HHcy group, the SHR + HHcy + FA group significantly reduced hyperhomocystinemia and malondialdehyde levels, and significantly increased superoxide dismutase activity and endothelial nitric oxide synthase expression; the SHR + HHcy + Res group also inhibited malondialdehyde levels and promoted endothelial nitric oxide synthase expression, but did not reduce hyperhomocystinemia. When comparing between the SHR + HHcy + FA group and the SHR + HHcy + Res group, folic acid significantly decreased hyperhomocystinemia and increased superoxide dismutase activity, while resveratrol significantly decreased blood pressure and angiotensin II expression.

Conclusions

Both resveratrol and folic acid reduced the levels of oxidative stress and promoted the expression of endothelial nitric oxide synthase in SHRs combined with hyperhomocystinemia. Moreover, resveratrol exhibited superior antihypertensive efficacy compared to folic acid, potentially attributed to its ability to inhibit angiotensin II expression.

Plasma mid-regional pro-adrenomedullin: A biomarker of the ischemic penumbra in hyperacute stroke

Reperfusion therapy has improved the outcomes of ischemic stroke but also emphasized the importance of ischemic penumbra. However, blood biomarkers are currently unavailable for this region. Adrenomedullin (ADM) is a neuroprotective peptide, secreted in a compensatory response to brain ischemia. We thus investigated whether an increase in mid-regional pro-ADM (MR-proADM), a stable peptide fragment of the ADM precursor, could act as a biomarker by predicting the ischemic penumbra in hyperacute ischemic stroke (HAIS). We prospectively enrolled consecutive HAIS patients (n = 119; median age, 77 years; male, 59.7%) admitted to our institutes from July 2017 to March 2019 and evaluated plasma MR-proADM levels within 4.5 h of onset. MR-proADM levels in HAIS were compared to healthy controls (n = 1298; median age, 58 years; male, 33.2%) in the Japan Multi-Institutional Collaborative Cohort Study from 2013 to 2017. Furthermore, we evaluated whether MR-proADM levels were associated with the penumbra estimated by clinical-diffusion mismatch (CDM) (National Institute of Health Stroke Scale [NIHSS] ≥8, diffusion ischemic core volume ≤25 ml), or magnetic resonance angiography-diffusion-weighted imaging mismatch (MDM) (NIHSS ≥5, a proximal vessel occlusion with core volume ≤25 ml, or a proximal vessel stenosis/distal vessel occlusion with core volume ≤15 ml). In a case-control study, multivariate logistic analysis showed a significant association between HAIS and MR-proADM ≥0.54 nmol/L (adjusted odds ratio, 7.92 [95% CI, 4.17-15.02], p < 0.001). Though MR-proADM levels in HAIS did not correlate with the ischemic core volume (r_s  = 0.09, p = 0.348), they were higher in HAIS with CDM (n = 34; 0.81 vs. 0.61 nmol/L, p < 0.001) or MDM (n = 26; 0.83 vs. 0.62 nmol/L, p = 0.002). These differences remained significant after adjusting baseline factors (adjusted odds ratio, 4.06 [95% CI, 1.31-12.55], p = 0.015 and 4.65 [1.35-16.11], p = 0.015, respectively). Plasma MR-proADM is elevated in HAIS, especially in those with a substantial penumbra, suggesting potential as a blood biomarker in this region.

Adrenomedullin Therapy in Moderate to Severe COVID-19

The 2019 coronavirus (COVID-19) pandemic is still in progress, and a significant number of patients have presented with severe illness. Recently introduced vaccines, antiviral medicines, and antibody formulations can suppress COVID-19 symptoms and decrease the number of patients exhibiting severe disease. However, complete avoidance of severe COVID-19 has not been achieved, and more importantly, there are insufficient methods to treat it. Adrenomedullin (AM) is an endogenous peptide that maintains vascular tone and endothelial barrier function. The AM plasma level is markedly increased during severe inflammatory disorders, such as sepsis, pneumonia, and COVID-19, and is associated with the severity of inflammation and its prognosis. In this study, exogenous AM administration reduced inflammation and related organ damage in rodent models. The results of this study strongly suggest that AM could be an alternative therapy in severe inflammation disorders, including COVID-19. We have previously developed an AM formulation to treat inflammatory bowel disease and are currently conducting an investigator-initiated phase 2a trial for moderate to severe COVID-19 using the same formulation. This review presents the basal AM information and the most recent translational AM/COVID-19 study.

Translational studies of adrenomedullin and related peptides regarding cardiovascular diseases

Adrenomedullin (AM) is a vasodilative peptide with various physiological functions, including the maintenance of vascular tone and endothelial barrier function. AM levels are markedly increased during severe inflammation, such as that associated with sepsis; thus, AM is expected to be a useful clinical marker and therapeutic agent for inflammation. However, as the increase in AM levels in cardiovascular diseases (CVDs) is relatively low compared to that in infectious diseases, the value of AM as a marker of CVDs seems to be less important. Limitations pertaining to the administrative route and short half-life of AM in the bloodstream (<30 min) restrict the therapeutic applications of AM for CVDs. In early human studies, various applications of AM for CVDs were attempted, including for heart failure, myocardial infarction, pulmonary hypertension, and peripheral artery disease; however, none achieved success. We have developed AM as a therapeutic agent for inflammatory bowel disease in which the vasodilatory effect of AM is minimized. A clinical trial evaluating this AM formulation for acute cerebral infarction is ongoing. We have also developed AM derivatives that exhibit a longer half-life and less vasodilative activity. These AM derivatives can be administered by subcutaneous injection at long-term intervals. Accordingly, these derivatives will reduce the inconvenience in use compared to that for native AM and expand the possible applications of AM for treating CVDs. In this review, we present the latest translational status of AM and its derivatives.

Molecular Dambusters: What Is Behind Hyperpermeability in Bradykinin-Mediated Angioedema?

In the last few decades, a substantial body of evidence underlined the pivotal role of bradykinin in certain types of angioedema. The formation and breakdown of bradykinin has been studied thoroughly; however, numerous questions remained open regarding the triggering, course, and termination of angioedema attacks. Recently, it became clear that vascular endothelial cells have an integrative role in the regulation of vessel permeability. Apart from bradykinin, a great number of factors of different origin, structure, and mechanism of action are capable of modifying the integrity of vascular endothelium, and thus, may participate in the regulation of angioedema formation. Our aim in this review is to describe the most important permeability factors and the molecular mechanisms how they act on endothelial cells. Based on endothelial cell function, we also attempt to explain some of the challenging findings regarding bradykinin-mediated angioedema, where the function of bradykinin itself cannot account for the pathophysiology. By deciphering the complex scenario of vascular permeability regulation and edema formation, we may gain better scientific tools to be able to predict and treat not only bradykinin-mediated but other types of angioedema as well.

Inflammatory markers and incident heart failure in older men: the role of NT-proBNP

Aim:

To determine the relationship between baseline inflammation (CRP and IL-6) with natriuretic peptide (NP) activity (measured by NT-proBNP) and incident heart failure (HF) in older men.

Methods & results:

In the British Regional Heart Study, 3569 men without prevalent myocardial infarction or HF were followed for mean 16.3 years; 327 developed HF. Baseline CRP and IL-6 were significantly and positively associated with NT-proBNP. Those in the highest CRP and IL-6 quartiles had an elevated risk of HF after age and BMI adjustment (HR = 1.42 [1.01–1.98] and 1.71 [1.24–2.37], respectively), which markedly attenuated after NT-proBNP adjustment (HR = 1.15 [0.81–1.63] and 1.25 [0.89–1.75], respectively).

Conclusion:

NP activity is associated with pro-inflammatory biomarkers and may explain the link between inflammation and incident HF.

Inflammation describes the body’s natural response to infections, injuries and toxins. Inflammation is a helpful response in the short term, but it is thought that long-lasting inflammation – for example, due to illnesses such as diabetes or obesity – may have harmful effects. Previous studies have found that people with higher levels of inflammatory molecules in the blood seem to be more likely to develop heart failure (HF) later on. The amount of fluid in the body is controlled, in part, by molecules in the blood known as ‘natriuretic peptides' (NPs). People with HF have much higher levels of NPs in their blood, and these are used to help diagnose HF. There are suggestions that inflammation and natriuretic peptides are linked to one another. Using a sample of men aged 60–79 years, who did not have HF, we compared blood markers of inflammation and NPs at a baseline examination. Men with higher blood inflammatory markers tended to have higher blood NP levels. We then followed these men up for an average of 16.3 years. Men with higher blood inflammatory markers at baseline were more likely to develop HF, as expected, even after accounting for differences in age and BMI. However, when we accounted for NP levels at baseline, the increased risk of HF with inflammation disappeared. This suggests that NP activity is important in the relationship between inflammation and the risk of HF. Future studies should account for this when examining the link. It is possible that NPs or, more likely, whatever is driving their release, may explain why people with inflammation are more likely to get HF.

Adrenomedullin for steroid-resistant ulcerative colitis: a randomized, double-blind, placebo-controlled phase-2a clinical trial

BACKGROUND

Adrenomedullin (AM) is a bioactive peptide having many pleiotropic effects, including mucosal healing and immunomodulation. AM has shown beneficial effects in rodent models and in preliminary study for patients with ulcerative colitis (UC). We performed a clinical trial to investigate the efficacy and safety of AM in patients with UC.

METHODS

This was a multi-center, double-blind, placebo-controlled phase-2a trial evaluating 28 patients in Japan with steroid-resistant UC. Patients were randomly assigned to four groups and given an infusion of 5, 10, 15 ng/kg/min of AM or placebo for 8 h per day for 14 days. The primary endpoint was the change in Mayo scores at 2 weeks. Main secondary endpoints included the change in Mayo scores and the rate of clinical remission at 8 weeks, defined as a Mayo score 0.

RESULTS

No differences in the primary or secondary endpoints were observed among the four groups at 2 weeks. Despite the insufficient tracking rate, the Mayo score at 8 weeks was only significantly decreased in the high-dose AM group (15 ng/kg/min) compared with the placebo group (- 9.3 ± 1.2 vs. - 3.0 ± 2.8, P = 0.035), with its rate of clinical remission at 8 weeks being significantly higher (3/3, 100% vs. 0/2, 0%, P = 0.025). We noted mild but no serious adverse events caused by the vasodilatory effect of AM.

CONCLUSIONS

In this double-blind randomized trial, we observed the complete remission at 8 weeks in patients with steroid-resistant UC receiving a high dose of AM.

CLINICAL TRIAL REGISTRY

JAPIC clinical trials information; Japic CTI-205255 (200410115290). https://www.clinicaltrials.jp/cti-user/trial/Search.jsp .

Adrenomedullin - Current perspective on a peptide hormone with significant therapeutic potential

The peptide hormone adrenomedullin (ADM) consists of 52 amino acids and plays a pivotal role in the regulation of many physiological processes, particularly those of the cardiovascular and lymphatic system. Like calcitonin (CT), calcitonin gene-related peptide (CGRP), intermedin (IMD) and amylin (AMY), it belongs to the CT/CGRP family of peptide hormones, which despite their low little sequence identity share certain characteristic structural features as well as a complex multicomponent receptor system. ADM, IMD and CGRP exert their biological effects by activation of the calcitonin receptor-like receptor (CLR) as a complex with one of three receptor activity-modifying proteins (RAMP), which alter the ligand affinity. Selectivity within the receptor system is largely mediated by the amidated C-terminus of the peptide hormones, which bind to the extracellular domains of the receptors. This enables their N-terminus consisting of a disulfide-bonded ring structure and a helical segment to bind within the transmembrane region and to induce an active receptor confirmation. ADM is expressed in a variety of tissues in the human body and is fundamentally involved in multitude biological processes. Thus, it is of interest as a diagnostic marker and a promising candidate for therapeutic interventions. In order to fully exploit the potential of ADM, it is necessary to improve its pharmacological profile by increasing the metabolic stability and, ideally, creating receptor subtype-selective analogs. While several successful attempts to prolong the half-life of ADM were recently reported, improving or even retaining receptor selectivity remains challenging.

Pro-adrenomedullin in acute decompensation of liver cirrhosis: relationship with acute-on-chronic liver failure and short-term survival

Background and aim: Acute-on-chronic liver failure (ACLF) is characterized by the presence of acute decompensation (AD) of cirrhosis, organ failures, and high short-term mortality rates. In present study, we explored whether Pro-adrenomedullin (Pro-ADM), a biomarker of sepsis, is a potential marker of outcome in patients admitted for AD or ACLF and whether it might be of additional value to conventional prognostic scoring systems in these patients.Methods: 332 consecutive patients with AD of cirrhosis were prospectively enrolled. Pro-ADM was measured for all patients at baseline. Cox regression analysis was used to evaluate the impact of pro-ADM on short-term survival and developing ACLF during hospital stay.Results: Serum pro-ADM levels were significantly high in non-survivors (p < .001) and showed significant correlation with ALT (r = 0.181, p = .001), INR (r = 0.144, p = .009), TB (r = 0.368, p < .001), Creatinine (r = 0.145, p = .004), MELD score (r = 0.334, p = <.001) and CLI-C OF score (r = 0.375, p= <.001). Serum pro-ADM at admission was shown to be a predictor of 28-day mortality independently of MELD and CLIF-C OF scores. Prognostic models incorporating pro-ADM achieved high C index for predicting 28-day mortality in AD patients of cirrhosis. Moreover, baseline pro-ADM was found to be predictive of ACLF development during hospital stay.Conclusions: Serum pro-ADM levels correlate with multiorgan failure and are independently associated with short-term survival and ACLF development in patients admitted for AD or ACLF.

Adrenomedullin has a role in angiogenic effects of resveratrol in adipose tissues of obese female rats

Obesity is a complex, chronic disease that arises according to the interaction between genetic and environmental factors. The expansion and growth of white adipose tissue (WAT) could be related to angiogenesis. Resveratrol and adrenomedullin (AdM) were used for the inhibition of angiogenesis in metabolically passive WAT for inhibiting the expansion of this tissue, and the activation of angiogenesis in metabolically active brown adipose tissue (BAT) for increasing daily energy consumption as a way of reducing obesity. Rats were divided into eight groups. Four obese groups were fed with a high-fat diet containing 60% fat as energy for three months. After obtaining obesity, 2.5 nmol/kg AdM and 10 mg/kg resveratrol were treated to experiment groups intraperitoneally (i.p.) every other day for four weeks. AdM and vascular endothelial growth factor A (VEGF-A) mRNA levels were detected with semi-quantitative PCR; protein levels were detected with Western Blotting. AdM and resveratrol are multifactorial molecules, thus, this study has revealed a few novel evidence. The results were distinct in the group and treatment levels. The results showed that resveratrol has a role in angiogenesis in obesity and contributed to AdM production. It is observed that AdM has regulated its expression and increased the effect of resveratrol in WAT. AdM and VEGF-A gene expressions could not be detected in BAT; however, it is suggested that resveratrol may have a pro-angiogenic effect in BAT of obese rats according to the protein levels. AdM also has regulated VEGF-A level according to the metabolic situation of the organism.

Safety, Tolerability, and Pharmacokinetics of Adrenomedullin in Healthy Males: A Randomized, Double-Blind, Phase 1 Clinical Trial

Background

Adrenomedullin (AM), an endogenous vasodilative peptide, has immunomodulative effects and acts as an accelerator of mucosal regeneration in the digestive tract. AM has shown beneficial effects in rodent models of inflammatory bowel disease and patients with ulcerative colitis. The present study aimed to evaluate the pharmacodynamic properties and safety of AM in healthy male adults in a phase 1 clinical trial.

Methods

This phase 1, randomized, double-blind, single-center study was conducted on healthy males aged 20–65 years. Subjects received either a placebo, 3 ng/kg/min AM, 9 ng/kg/min AM, or 15 ng/kg/min AM via continuous 12-h intravenous infusion. Other subjects received either placebo or 15 ng/kg/min AM for 8 h per day for 7 days. Adverse events (AEs), vital signs, physical examinations, laboratory tests, electrocardiograms (ECG), and pharmacokinetics were assessed.

Findings

All 24 subjects in the single-dose test completed the study. Of the 12 subjects in multiple dosing test, one from the AM group withdrew owing to a headache. No serious AEs were reported. Hemodynamic parameters were well maintained in all subjects. Slight ECG abnormalities were observed in the single-dose test. The plasma concentration of AM progressively increased in a dose-dependent manner and reached C_max at the end of administration. Plasma AM rapidly returned to baseline concentrations after termination, with a T_1/2 of under 60 min.

Interpretation

This is the first phase 1 trial in healthy men evaluating the safety of AM. Our results demonstrate the safety and tolerability of AM for subsequent Phase 2 trials.

Circulating Biologically Active Adrenomedullin Predicts Organ Failure and Mortality in Sepsis

BACKGROUND

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Biologically active adrenomedullin (bio-ADM) is an emerging biomarker for sepsis. We explored whether bio-ADM concentration could predict severity, organ failure, and 30-day mortality in septic patients.

METHODS

In 215 septic patients (109 patients with sepsis; 106 patients with septic shock), bio-ADM concentration was measured at diagnosis of sepsis, using sphingotest bio-ADM (Sphingotec GmbH, Hennigsdorf, Germany) and analyzed in terms of sepsis severity, vasopressor use, and 30-day mortality. The number of organ failures, sequential (sepsis-related) organ failure assessment (SOFA) score, and 30-day mortality were compared according to bio-ADM quartiles.

RESULTS

Bio-ADM concentration was significantly higher in patients with septic shock, vasopressor use, and non-survivors than in patients with solitary sepsis, no vasopressor use, and survivors, respectively (all P<0.0001). Bio-ADM quartiles were associated with the number of organ failures (P<0.0001), as well as SOFA cardiovascular, renal, coagulation, and liver subscores (all P<0.05). The 30-day mortality rate showed a stepwise increase in each bio-ADM quartile (all P<0.0001). Bio-ADM concentration and SOFA score equally predicted the 30-day mortality (area under the curve: 0.827 vs 0.830).

CONCLUSIONS

Bio-ADM could serve as a useful and objective biomarker to predict severity, organ failure, and 30-day mortality in septic patients.

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.

Adrenomedullin surges are linked to acute episodes of the systemic capillary leak syndrome (Clarkson disease)

BACKGROUND

Systemic Capillary Leak Syndrome (SCLS) is an extremely rare and life-threatening vascular disorder of unknown etiology. SCLS is characterized by abrupt and transient episodes of hypotensive shock and edema due to plasma leakage into peripheral tissues. The disorder has garnered attention recently because its initial presentation resembles more common vascular disorders including systemic anaphylaxis, sepsis, and acute infections with the Ebola/Marburg family of filoviruses. Although approximately 70-85% of patients with SCLS have a concurrent monoclonal gammopathy of unknown significance (MGUS), any contribution of the paraprotein to acute flares is unknown.

PROCEDURE

To identify circulating factors that might trigger acute SCLS crises, we profiled transcriptomes of paired peripheral blood mononuclear cell fractions obtained from patients during acute attacks and convalescent intervals by microarray.

RESULTS

This study uncovered 61 genes that were significantly up- or downregulated more than 2.5-fold in acute samples relative to respective baselines. One of the most upregulated genes was ADM, which encodes the vasoactive peptide adrenomedullin. A stable ADM protein surrogate (pro-ADM) was markedly elevated in SCLS acute sera compared to remission samples or sera from healthy controls. Monocytes and endothelial cells (ECs) from SCLS subjects expressed significantly more ADM in response to proinflammatory stimuli compared to healthy control cells. Application of ADM to ECs elicited protective effects on vascular barrier function, suggesting a feedback protective mechanism in SCLS.

CONCLUSIONS

Since ADM has established hypotensive effects, differentiating between these dual actions of ADM is crucial for therapeutic applications aimed at more common diseases associated with increased ADM levels.

Prognostic Value of Adrenomedullin and Natriuretic Peptides in Uroseptic Patients Induced by Ureteroscopy

The aim of this paper is to investigate whether urosepsis is related to irrigation pressure of ureteroscopy (URS) and evaluate the prognostic value of adrenomedullin (ADM) and atrial and brain natriuretic peptides (ANP and BNP) in URS-induced uroseptic patients. From July 2008 to October 2013, we enrolled 332 patients with untreated unilateral ureteral obstruction (UUO). The UUO group included three subgroups of, respectively, 118, 132, and 82 patients who underwent URS under intermittent stable irrigation pressure of, respectively, 80, 120, and 160 mmHg. The plasma concentrations of ADM, ANP, and BNP were measured in all subjects. URS was performed for all UUO patients; the values of the three peptides were measured again after URS. Irrigation pressure and stone size were independent risk factors of urosepsis. After URS, the plasma concentrations of ADM, ANP, and BNP were significantly higher in uroseptic patients. Moreover, the concentrations were significantly higher depending on the disease severity. Plasma concentrations of the three peptides were correlated with plasma ET concentration in the uroseptic patients. The areas under receiver operating characteristic (ROC) curve of ADM, ANP, and BNP for predicting urosepsis were 0.811, 0.728, and 0.764, respectively. In conclusion, ADM, along with ANP and BNP, is valuable for prognosis in urosepsis secondary to URS which is associated with irrigation pressure.

Biomarkers for the early diagnosis of bacterial infection and the surveillance of hepatocellular carcinoma in cirrhosis

The early detection of bacterial infections and hepatocellular carcinoma (HCC) could ameliorate the prognosis of cirrhosis. C-reactive protein and procalcitonin are under investigation in the setting of cirrhosis as markers of sepsis. In the attempt to discriminate bacterial infection from systemic inflammation, the role of novel biomarkers such as lypopolysaccharide binding-protein, mid-regional fragment of pro-adrenomedullin and delta neutrophil index are currently in development. Concerning HCC, many studies attempted to evaluate biomarkers in the hope of ameliorating the accuracy of the surveillance based on ultrasound. The use of α-fetoprotein (AFP) has been extensively investigated, as well as other biomarkers expressed in the serum of HCC patients like lens culinaris agglutinin-reactive fraction of AFP, des-γ-carboxy prothrombin, glypican-3, α-l-fucosidase and their combined use.

Less increase of copeptin and MR-proADM due to intervention with selenium and coenzyme Q10 combined: Results from a 4-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens

Intervention with selenium and coenzyme Q10 have recently been found to reduce mortality and increase cardiac function. The mechanisms behind these effects are unclear. As selenium and coenzyme Q10 is involved in the anti-oxidative defence, the present study aimed to evaluate effects of selenium and coenzyme Q10 on copeptin and adrenomedullin as oxidative stress biomarkers. Therefore 437 elderly individuals were included and given intervention for 4 years. Clinical examination and blood samples were undertaken at start and after 18 and 48 months. Evaluations of copeptin and MR-proADM changes were performed using repeated measures of variance. Cardiovascular mortality was evaluated using a 10-year-period of follow-up, and presented in Kaplan-Meier plots. A significant increase in copeptin level could be seen in the placebo group during the intervention period (from 9.4 pmol/L to 15.3 pmol/L), compared to the active treatment group. The difference between the groups was confirmed in the repeated measurement of variance analyses (P = 0.031) with less copeptin increase in the active treatment group. Furthermore, active treatment appeared to protect against cardiovascular death both in those with high and with low copeptin levels at inclusion. Less increase of MR-proADM could also be seen during the intervention in the active treatment group compared to controls (P = 0.026). Both in those having an MR-proADM level above or below median level, significantly less cardiovascular mortality could be seen in the active treatment group (P = 0.0001, and P = 0.04 respectively). In conclusion supplementation with selenium and coenzyme Q10 during four years resulted in less concentration of both copeptin and MR-proADM. A cardioprotective effect of the supplementation was registered, irrespective of the initial levels of these biomarkers, and this protection was recognized also after 10 years of observation.

Influence of bed rest on plasma galanin and adrenomedullin at presyncope

BACKGROUND

The role of hormones in reduced orthostatic tolerance following long-term immobilization remains uncertain. We have previously shown that plasma concentrations of adrenomedullin and galanin, two peptides with vasodepressor properties, rise significantly during orthostatic challenge. We tested the hypothesis that bedrest immobilization increases the rise in adrenomedullin and galanin during orthostatic challenge leading to presyncope.

MATERIALS AND METHODS

We measured baseline (supine), presyncope and recovery (10 min postpresyncope, supine) levels of adrenomedullin and galanin in 8 healthy men, before and after 21 days of -6° head-down bed rest (HDBR). Presyncope was elicited using a combined head-up tilt and graded lower body negative pressure protocol. Orthostatic tolerance was defined as the time taken from the commencement of head-up tilt to the development of presyncope.

RESULTS

Orthostatic tolerance time after HDBR reduced by 8·36 ± 5·39 min (P = 0·0032). HDBR increased plasma adrenomedullin concentration to orthostatic challenge (P = 0·0367). Compared to pre-HDBR, a significant rise in post-HDBR presyncopal (P < 0·001) and recovery adrenomedullin concentration (P < 0·01) was demonstrated. In contrast, we observed no change in pre- and post-HDBR galanin levels to orthostatic challenge.

CONCLUSIONS

Bedrest immobilization appears to affect adrenomedullin levels in that greater increases in adrenomedullin occur at presyncope following bedrest immobilization. Due to its peripheral vasculature hypotensive effect, the greater levels of adrenomedullin at presyncope following bedrest immobilization may have contributed to the reduced orthostatic capacity postbedrest.

Pathophysiological functions of adrenomedullin and natriuretic peptides in patients with primary aldosteronism

To measure the plasma concentrations of adrenomedullin (ADM),atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP), and investigate their pathophysiological functions in patients with primary aldosteronism (PA). Between June 2006 and December 2012, we recruited 25 patients with untreated PA, 30 patients with untreated low-renin essential hypertension (EH), and 35 healthy control subjects. The plasma concentrations of ADM, ANP, and BNP were measured in all the subjects. After 4 weeks of effective antihypertensive therapy with slow-release nifedipine, the three peptides were measured again in the PA and low-renin EH subjects. Unilateral laparoscopic adrenalectomy was performed in all the PA patients; 2 weeks after surgery, the three peptides were measured again. The PA patients had significantly higher plasma concentrations of ADM, ANP, and BNP than the low-renin EH and control subjects. The low-renin EH and control subjects significantly differed in the concentrations of the three peptides between low-renin EH and control subjects. ADM was the most important peptide associated with aldosterone or blood pressure in the PA patients. Plasma ADM concentration was not only correlated with plasma aldosterone concentrations, but also with systolic and diastolic blood pressures, and plasma ANP and BNP concentrations in the PA patients. By contrast, ADM concentration was not related to blood urea nitrogen levels, serum creatinine levels, and glomerular filtration rates. After antihypertensive treatment, the concentrations of the three peptides significantly decreased in the low-renin EH patients, but remained unchanged in the PA subjects. However, these concentrations significantly decreased 2 weeks after laparoscopic adrenalectomy in the PA subjects. ADM, ANP, and BNP possibly participate in the mechanisms counteracting further elevation of blood pressure or plasma volume expansion resulting from aldosterone hypersecretion in PA patients. An ADM/aldosterone local regulatory mechanism may be involved in regulating adrenal adenoma functions.

Adrenomedullin attenuates aortic cross-clamping-induced myocardial injury in rats

BACKGROUND

In this study we investigate the effects of adrenomedullin on myocardial injury after ischemia-reperfusion (I/R) after abdominal aortic surgery.

METHODS

Thirty-two Wistar rats were randomized into 4 groups (n = 8) as follows: control group (sham laparotomy), the aortic I/R group, aortic I/R plus adrenomedullin group (underwent aortic I/R periods, and received a bolus intravenous injection of .05 μg/kg/min adrenomedullin), and the control plus adrenomedullin group.

RESULTS

Biochemical analysis showed that aortic I/R significantly increased (P < .05) the plasma levels of troponin-I and tumor necrosis factor-α, and the myocardial tissue levels of malondialdehyde, superoxide dismutase, catalase, and angiotensin II, whereas aortic I/R plus adrenomedullin significantly decreased these same factors (P < .05). Aortic I/R significantly increased (P < .05) myocardial tissue levels of nitric oxide whereas aortic I/R plus adrenomedullin significantly increased the same factor (P < .05).

CONCLUSIONS

These results indicate that adrenomedullin has protective effects against myocardial injury induced by abdominal aortic I/R in rats.

Adrenomedullin ameliorates the development of atherosclerosis in apoE-/- mice

Adrenomedullin (ADM) is a multifunctional peptide regulating cardiovascular homeostasis. We studied the role of ADM in the pathogenesis of atherosclerosis by investigating changes in ADM and its receptors - calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) - in aorta of apoE-/- mice and the effect of exogenous ADM administration. ApoE-/- mice were fed an atherogenic diet for 4 weeks, and apoE-/-+ADM mice were additionally given subcutaneous injections of ADM, 300ng/kg/h, for 4 weeks. ApoE-/- mice fed an atherogenic diet showed hyperlipidemia, a large plaque area and increased vessel wall thickness. The mRNA expression and protein level of ADM/ADM receptors were increased in the aorta, compared with C57BL/6J mice. The elevated mRNA level of CRLR and RAMPs correlated positively with ADM mRNA level. Radioimmunoassay revealed a higher plasma and aorta ADM content, by 61.6% and 285% (both P<0.01), respectively, in apoE-/- mice than that in C57BL/6J mice. Exogenous ADM significantly ameliorated dyslipidemia in apoE-/- mice. ADM-treated mice showed fewer aortic plaques, decreased plaque area, by 76% (P<0.01), and reduced ratio of plaque area to luminal area, by 65% (P<0.01), and ultrasonography revealed significantly reduced intima-media thickness of the ascending branch and abdominal aorta. The results suggest that atherosclerotic apoE-/- mice fed an atherogenic diet showed upregulated endogenous ADM and its receptors, and exogenous ADM treatment ameliorated the dyslipidemia and vascular atherosclerotic lesions. ADM/ADM receptors might be an important protective system against atherosclerosis and could become a new target of prevention and therapy for atherosclerosis.

Cloning of prepro-adrenomedullin and mRNA expression in cats

The objective of this paper was to evaluate the sequence of feline prepro-adrenomedullin (AM) and its tissue distribution and to investigate whether expression of feline AM mRNA increases in association with spontaneous cardiomyopathy. The feline prepro-AM cDNA sequence and deduced amino acids were 564 base pairs and 188 residues, respectively. The cDNA sequences of feline prepro-AM including AM and proadrenomedullin N-terminal 20 peptide showed high homology with those of other mammalian species. The mRNA expression of AM was detectable in various normal tissues. The mRNA levels of AM were elevated in hearts with cardiomyopathy compared with normal hearts. This study suggests that AM has an important role as a neurohumoral factor in cats with spontaneous heart diseases.

Gene expression of adrenomedullin in canine normal tissues and diseased hearts

The purposes of this study were to determine the tissue distribution of canine adrenomedullin (AM) and to determine whether increased canine AM mRNA expression is associated with congestive heart failure (CHF) due to mitral regurgitation (MR). Canine AM mRNA expression was detectable in various normal tissues, including cardiovascular tissues. In addition, the AM mRNA expression in the left atrium of dogs with MR was significantly higher than that in normal subjects. In conclusion, AM is a potential neurohumoral factor in dogs with CHF due to MR.

Effects of adrenomedullin on systolic and diastolic myocardial function

Adrenomedullin (AM) effects were studied in rabbit papillary muscles by adding increasing concentrations (10(-10) to 10(-6)M) either alone or after pre-treatment with l-NNA, indomethacin, AM22-52 (AM receptor antagonist), CGRP(8-37) (CGRP receptors antagonist), KT5720 (PKA inhibitor), as well as after endocardial endothelium (EE) removal. Passive length-tension relations were constructed before and after a single concentration of AM (10(-6)M). AM concentration-dependently induced negative inotropic and lusitropic effects, and increased resting muscle length (RL). At 10(-6)M, AT, dT/dt(max) and dT/dt(min) decreased 20.9+/-4.9%, 18.3+/-7.3% and 16.7+/-7.8%, respectively, and RL increased to 1.010+/-0.004L/L(max). Correcting RL to its initial value resulted in a 26.6+/-6.4% decrease of resting tension, indicating decreased muscle stiffness, also patent in the down and rightward shift of the passive length-tension relation. The negative inotropic effect of AM was dependent on its receptor, CGRP receptor, PKA, the EE and NO, while the effects of AM on myocardial stiffness were abolished by EE damage and NO inhibition. This latter effect represents a novel mechanism of acute neurohumoral modulation of diastolic function, suggesting that AM is an important regulator of cardiac filling.

Adrenomedullin is increased by pulsatile shear stress on the vascular endothelium via periodic acceleration (pGz)

Periodic acceleration (pGz) is produced by a platform which moves the supine body repetitively in a headward to footward direction. The imparted motion produces pulsatile shear stress on the vascular endothelium. Pulsatile shear stress on the vascular endothelium has been shown to elicit production of a host of cardioprotective, cytoprotective mediators. The purpose of this study was to ascertain if pGz also enhances production of adrenomedullin (AM) in normal healthy swine. Twelve pigs (weight range 20-30 kg) were anesthetized, intubated and placed on conventional mechanical ventilation. All animals were secured to the motion platform. In one group (pGz) (n=7) was activated for 1h, and monitored for an additional 3h. A control group (CONT) (n=5) served as time control. Arterial blood gases, hemodynamic measurements, and serum for AM, interleukin 4, 6 and thromboxane B(2) (TBXB2) were measured at baseline, immediately after pGz, and 3h after pGz had been discontinued. There was no significant change from baseline value in IL-4, IL-6 or TBXB2. Mean arterial blood pressure decreased in pGz-treated animals from 115+/-10 at baseline to 90+/-8 after 60 min of pGz (p<0.01). AM levels increase from 776+/-176 pg/ml baseline to 1160+/-68 pg/ml immediately after pGz, and remained elevated to 1584+/-160 pg/ml, 3h after pGz (p<0.01 vs. BL). This is the first report of AM-enhanced production using a non-invasive method of increasing pulsatile shear stress on the vascular endothelium. pGz increases production of AM in normal healthy swine. These changes are independent of IL-4, IL-6 or TBXB2 production.

Mice heterozygous for adrenomedullin exhibit a more extreme inflammatory response to endotoxin-induced septic shock

Adrenomedullin (AM) is a highly conserved peptide that can act as a potent vasodilator, anti-microbial factor and anti-inflammatory factor. Several studies have implicated diverse roles for AM in regulating the inflammatory and hemodynamic responses to septic shock. Moreover, during sepsis the receptors that mediate AM signaling [calcitonin receptor-like receptor (calcrl) and receptor activity modifying proteins (RAMP) 2 and 3] undergo dynamic and robust changes in their expression. Although numerous studies have used animal models to study the role of administered or increased AM in septic animals, genetic studies to determine the consequences of reduced AM during septic shock have not yet been performed. Here, we used a murine model of lipopolysaccharide (LPS)-induced septic shock to assess the inflammatory response in mice heterozygous for the AM gene. Following LPS challenge, AM(+/-) mice had higher expression of TNF-alpha and IL-1beta than LPS-treated wild-type (WT) controls. Consequently, serum TNF-alpha was also significantly elevated in LPS-treated AM(+/-) mice compared to WT LPS-treated mice. We also observed higher serum levels of liver enzymes, suggesting more advanced end-organ damage in mice with genetically reduced AM. Finally, we found that RAMP2 and calcrl expression levels were markedly reduced in LPS-treated mice, whereas RAMP3 expression was significantly elevated. Importantly, these changes in receptor gene expression were conserved in AM(+/-) mice, demonstrating that AM peptide itself does not impact directly on the expression of the genes encoding its receptors. We, therefore, conclude that during septic shock the dynamic modulation of AM and its receptors primarily functions to dampen the inflammatory response.

AMELIORATION OF CARDIAC FUNCTION IN CHRONIC MYOCARDIAL INFARCTED RATS FOLLOWING ADMINISTRATION OF VECTOR pcDNA3.1AM

1. The present study was designed to examine the cardiovascular effects of intravenously administered pcDNA3.1AM, a recombinant non-virus vector carrying a rat adrenomedullin (AM) gene translation fragment, in rats with chronic cardiac dysfunction induced by ligation of the left descending coronary artery. 2. Haemodynamic parameters were recorded by intraventricular catheterization. In situ hybridization and polymerase chain reaction (PCR) were performed to identify the distribution of the introduced vector. The concentration of AM was determined by radioimmunoassay. 3. Progressive cardiac dysfunction was observed following coronary artery ligation, as indicated by a significant reduction in mean arterial pressure (MAP) and increases in both central venous pressure (CVP) and end-diastolic pressure of the left ventricle (LVEDP; P < 0.01). Administration of pcDNA3.1AM significantly attenuated the progressive cardiac dysfunction and lowered the elevated CVP and LVEDP. The introduced vector was widely distributed in different organs, including the lungs, kidney, heart, liver, spleen and brain. However, intense staining of pcDNA3.1 AM was observed in the lungs and kidneys. The introduced vector was localized mainly in the endothelial cells of blood vessels. Radioimmunoassay showed elevated levels of AM in the plasma and lung and heart after surgery, but there was no significant further increase in the concentration of AM after pcDNA3.1AM delivery. 4. The present study has provided some novel findings on the potential beneficial effects of AM gene delivery on chronic cardiac function in rats. Expression of AM by a non-virus vector may also have therapeutic value against cardiac dysfunction in vivo.

Adrenomedullin ameliorates lipopolysaccharide-induced acute lung injury in rats

Adrenomedullin (AM), an endogenous peptide, has been shown to have a variety of protective effects on the cardiovascular system. However, the effect of AM on acute lung injury remains unknown. Accordingly, we investigated whether AM infusion ameliorates lipopolysaccharide (LPS)-induced acute lung injury in rats. Rats were randomized to receive continuous intravenous infusion of AM (0.1 microg x kg(-1) x min(-1)) or vehicle through a microosmotic pump. The animals were intratracheally injected with either LPS (1 mg/kg) or saline. At 6 and 18 h after intratracheal instillation, we performed histological examination and bronchoalveolar lavage and assessed the lung wet/dry weight ratio as an index of acute lung injury. Then we measured the numbers of total cells and neutrophils and the levels of tumor necrosis factor (TNF)-alpha and cytokine-induced neutrophil chemoattractant (CINC) in bronchoalveolar lavage fluid (BALF). In addition, we evaluated BALF total protein and albumin levels as indexes of lung permeability. LPS instillation caused severe acute lung injury, as indicated by the histological findings and the lung wet/dry weight ratio. However, AM infusion attenuated these LPS-induced abnormalities. AM decreased the numbers of total cells and neutrophils and the levels of TNF-alpha and CINC in BALF. AM also reduced BALF total protein and albumin levels. In addition, AM significantly suppressed apoptosis of alveolar wall cells as indicated by cleaved caspase-3 staining. In conclusion, continuous infusion of AM ameliorated LPS-induced acute lung injury in rats. This beneficial effect of AM on acute lung injury may be mediated by inhibition of inflammation, hyperpermeability, and alveolar wall cell apoptosis.

Omapatrilat enhances adrenomedullin's reduction of cardiomyocyte cell death

The objective of this study was to determine whether adrenomedullin, a vasodilator peptide, modulates the process of cell death in cardiomyocytes and whether its effect would be enhanced by the endopeptidase inhibitor omapatrilat, which reduces adrenomedullin degradation. Further, we sought to determine whether the effect of adrenomedullin involved an action to preserve mitochondrial transmembrane potential (DeltaPsi(m)). Cardiomyocytes in culture were treated with agents that interrupted the mitochondrial electron transport chain, inhibiting glycolysis and oxidative phosphorylation. Cell death was evaluated by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay and DeltaPsi(m) was assessed by fluorescent microscopy. Cytochrome c loss from mitochondria and appearance in cytosol was determined by Western blotting. Potassium cyanide (KCN) plus deoxyglucose or antimycin A, for 24 h, produced significant (p<0.01) concentration-dependent reductions in cell viability or increases in cell death. Adrenomedullin reduced cell death produced in this manner and the effect of adrenomedullin was enhanced by treatment with omapatrilat. In contrast, there was no additional reduction in cell death by lisinopril treatment. Omapatrilat plus adrenomedullin reduced the KCN plus deoxyglucose-induced increase in cytosolic cytochrome c. A likely mechanism centers on the ability of adrenomedullin plus omapatrilat to prevent the decline in mitochondrial DeltaPsi(m) produced by KCN plus deoxyglucose treatment. In summary, adrenomedullin plus omapatrilat limited the decline in mitochondrial DeltaPsi(m) that accompanies interruption of mitochondrial metabolism and limited the extent of cell death in cardiomyocytes treated with KCN plus deoxyglucose or antimycin. Adrenomedullin plus the endopeptidase inhibitor omapatrilat may be a useful strategy to protect cardiomyocytes from cell death, in conditions associated with impairment of mitochondrial function.

The myocardial response to adrenomedullin involves increased cAMP generation as well as augmented Akt phosphorylation

In this work we aimed to observe (1) the changes in adrenomedullin (AM) and its receptor system - calcitonin receptor-like receptor (CRLR) and receptor activity modifying proteins (RAMPs) - in myocardial ischemic injury and (2) the response of injuried myocardia to AM and the phosphorylation of Akt to illustrate the protective mechanism of AM in ischemic myocardia. Male SD rats were subcutaneously injected with isoproterenol (ISO) to induce myocardial ischemia. The mRNA levels of AM, CRLR, RAMP1, RAMP2 and RAMP3 were determined by RT-PCR. Protein levels of Akt, phosphor-Akt, CRLR, RAMP1, RAMP2 and RAMP3 were assayed by Western blot. Results showed that, compared with that of the controls, ISO-treated rats showed lower cardiac function and myocardial injury. The mRNA relative amount of AM, CRLR, RAMP1, RAMP2 and RAMP3 in the myocardia of ISO-treated rats was increased. The elevated mRNA levels of CRLR, RAMP1, RAMP2 and RAMP3 were positively correlated with AM content in injured myocardia. The protein levels of CRLR, RAMP1, RAMP2 and RAMP3 in injured myocardia were increased compared with that of control myocardia. AM-stimulated cAMP generation in myocardia was elevated in the ISO group, and was antagonized by AM(22-52) and CGRP(8-37). Western blot analyses revealed that AM significantly enhanced Akt phosphorylation in injured myocardia, which was blocked by pretreatment with AM(22-52) or CGRP(8-37). Ischemia-injured myocardia hyper-expressed AM and its receptors - CRLR, RAMP1, RAMP2 and RAMP3 - and the response of ischemic myocardia to AM was potentiated, and the level of Akt phosphorylation was also increased, which suggests that changes in cardiac AM/AM receptor might play an important role in the pathogenesis of myocardial ischemic injury.

Effect of adrenergic blockade on plasma adrenomedullin concentration during static handgrip in patients with heart failure

Our previous study showed that static handgrip caused increases in the plasma adrenomedullin (ADM) both in patients with heart failure (HF) and healthy subjects. The present study was designed to determine the role of the sympathetic nervous system in mediating plasma ADM changes during handgrip in patients with HF. Twelve male HF patients (II class NYHA) treated with carvedilol, a non-selective adrenergic blocker (TC) and 12 patients untreated with carvedilol (UC) performed two 3-min bouts of static handgrip at 30% of maximal voluntary contraction, alternately with each hand. At the end of both exercise bouts and in 5 min of the recovery period, plasma ADM and catecholamines were determined. In addition, heart rate, blood pressure and stroke volume (SV) were measured. The baseline plasma ADM, noradrenaline (NA) and adrenaline (A) levels were similar in the two groups of patients, while SV was higher (P<0.05) in TC than in UC. During exercise plasma ADM concentrations were lower (P<0.05) in TC than in UC, but the handgrip-induced increases in plasma ADM did not differ between the groups. Plasma ADM correlated with NA concentrations (r = 0.764) and with SV (r = -0.435) and increases in plasma ADM expressed as percentage of baseline values correlated with those of plasma NA (r = 0.499), diastolic BP (r = 0.550) and total peripheral resistance (r = 0.435). The study suggests that the sympathetic nervous system may be involved in the stimulation of ADM secretion during static exercise either directly or by changes in the haemodynamic response.

Plasma adrenomedullin levels in patients with polycystic ovary syndrome

OBJECTIVE

To evaluate adrenomedullin levels in patients with polycystic ovary syndrome (PCOS).

DESIGN

Prospective study.

SETTING

Department of obstetrics and gynecology in a university hospital.

PATIENT(S)

Thirty-eight women with PCOS and 29 healthy control subjects were enrolled in the study.

INTERVENTION(S)

Plasma adrenomedullin, serum androstenedione, free T, T, DHEAS, SHBG, thyrotropin, PRL, FSH, LH, and E2 were measured in each subject. Insulin resistance was estimated by fasting insulin level, fasting glucose:insulin ratio and 75-g glucose tolerance test for 2 hours.

MAIN OUTCOME MEASURE(S)

Plasma adrenomedullin levels and correlations among adrenomedullin and gonadotropins, female sex steroids, androgens, and insulin resistance.

RESULT(S)

There was no significant difference concerning plasma adrenomedullin concentrations between the groups. In patients with PCOS, fasting glucose, fasting insulin, body mass index, and free T were inversely correlated with the plasma adrenomedullin. Plasma adrenomedullin was significantly correlated with glucose:insulin ratio. After controlling for body mass index, there were no significant correlations between the above-mentioned parameters.

CONCLUSION(S)

Adrenomedullin may play a role in regulating the insulin metabolism in patients with PCOS.

Plasma adrenomedullin relation with Doppler-derived dP/dt in patients with congestive heart failure

BACKGROUND

Increased circulating adrenomedullin (AM) concentration has been reported in congestive heart failure (HF) and considered as a possible marker of cardiac dysfunction.

HYPOTHESIS

The study was undertaken to assess the relationship between circulating AM concentration and left ventricular (LV) functional state, estimated by echo-Doppler techniques in patients with mild to moderate HF and different degrees of LV dysfunction.

METHODS

Plasma AM, B-type natriuretic peptide (BNP), and N-terminal (NT) proBNP levels were measured in 55 patients with HF (New York Heart Association [NYHA] I n = 8, II n = 26, III n = 21) and in 20 controls; dP/dt was calculated by the Doppler tracing of the mitral regurgitation jet.

RESULTS

The study was completed in 51 patients. Adrenomedullin levels were higher than in controls (19.2 +/- 1.4 vs. 13.3 +/- 0.7, p < 0.005) and elevated in proportion to NYHA functional class. B-type natriuretic peptide and NT-proBNP were 344 +/- 67 vs. 12 +/- 2 pg/ml and 2196 +/- 623 vs. 52 +/- 4 pg/ml, respectively (p < 0.0001); dP/dt was better related to AM (r = 0.582, p < 0.001) than to the other peptides. Adrenomedullin was significantly (p < 0.001) different between patients grouped according to the dP/dt cut-off predictive of event-free survival.

CONCLUSIONS

The combination of depressed contractility and increased AM may provide a clue for further characterization of the severity of LV dysfunction in HF, independent of baseline LV ejection fraction.

Effects of Adrenomedullin on Cardiac Oxidative Stress and Collagen Accumulation in Aldosterone-Dependent Malignant Hypertensive Rats

We examined the effects of adrenomedullin on cardiac oxidative stress and collagen accumulation in aldosterone-dependent malignant hypertensive rats. Spontaneously hypertensive rats (SHRs) were treated with one of the following combinations for 4 weeks: tap water and vehicle [0.5% ethanol, subcutaneously (s.c.), n = 5], 1% NaCl in drinking water and vehicle (n = 8), 1% NaCl and aldosterone (0.75 microg/h s.c., n = 8), and 1% NaCl, aldosterone, and adrenomedullin (1.3 microg/kg/h s.c., n = 8). Systolic blood pressure (SBP) and left ventricular (LV) weight were higher in aldosterone-treated SHRs than vehicle- or vehicle/1% NaCl-treated SHRs. Thiobarbituric acid reactive substances (TBARS) levels and NADPH oxidase activity in LV tissues of aldosterone-treated SHRs were also higher than those of vehicle- or vehicle/1% NaCl-treated SHRs, and these changes were associated with increases in LV mRNA levels of p22phox, gp91phox, fibronectin, collagen types I and III, as well as collagen content. Treatment with adrenomedullin did not alter SBP or LV weight but attenuated aldosterone-induced increases in TBARS levels, NADPH oxidase activity, and mRNA levels of p22phox, gp91phox, fibronectin, collagen types I and III, as well as collagen content in LV tissues. These data suggest that NADPH oxidase-mediated reactive oxygen species production is involved in the pathogenesis of cardiac collagen accumulation in aldosterone-dependent malignant hypertensive rats and that the cardioprotective effects of adrenomedullin are mediated through the suppression of this pathway.

Increased Production of Adrenomedullin in Glomeruli from Anti-Glomerular Basement Membrane Glomerulonephritis Rats Treated with Methylprednisolone

BACKGROUND/AIMS

Adrenomedullin (AM) has anti-proliferative and apoptotic effects on mesangial cells (MCs). Both effects play an important role in the progression of glomerulonephritis (GN). Glucocorticoids are widely used for the treatment of GN; however, the relationship between AM regulation in MCs or glomeruli and glucocorticoid treatment has not been clarified.

METHODS

Using the cultured rat MCs, AM secretion induced by methylprednisolone (m-PSL), and MC proliferation and apoptosis caused by AM were examined. In addition, the role of AM receptor antagonist, AM(22-52), was also investigated. Then, we made an anti-glomerular basement membrane (GBM) GN rat model and compared the AM expression and production in each glomeruli obtained from the control or m-PSL-treated anti-GBM GN rats.

RESULTS

In the cultured rat MCs, AM secretion was increased by m-PSL. MC proliferation was inhibited, while MC apoptosis was increased by AM. MC apoptosis was inhibited by the addition of AM(22-52). M-PSL therapy ameliorated the progression of anti-GBM GN rats. AM expression and production were increased in the glomeruli from m-PSL-treated rats compared to the controls.

CONCLUSION

Considering the anti-proliferative and apoptotic effects of AM on MCs, increased AM in the glomeruli might participate in the improvement of glomerular lesions in anti-GBM GN rats treated with m-PSL.

Mitochondrial regulation of hypoxia-induced increase of adrenomedullin mRNA in HL-1 cells

Hypoxia upregulates the expression of the cardioprotective peptide adrenomedullin in cardiomyocytes. We characterized this pathway in murine HL-1 cardiomyocytes. Inhibition of mitochondrial complexes I, III, and IV largely, but not completely, reduced hypoxic adrenomedullin mRNA increase in gas-impermeable culture plates. Complex III inhibition was also effective in permeable culture plates, so that this effect is unlikely due to intracellular oxygen redistribution, whereas complex I blockade was ineffective in permeable plates. Complex II does not participate in this effect, as shown by chemical and siRNA inactivation. ROS scavenging by nitroblue tetrazolium and general flavoprotein inhibition by diphenyleniodonium nearly abrogated the hypoxic adrenomedullin mRNA increase. Thus, ROS production by flavoproteins is crucial for hypoxic upregulation of adrenomedullin mRNA in murine HL-1 cardiomyocytes. These ROS originate both from the mitochondrial complex III and from additional, presumably extramitochondrial, sources. Mitochondrial oxygen consumption appears to have impact on oxygen availability at these extramitochondrial sensors.

Potentiated response to adrenomedullin in myocardia and aortas in spontaneously hypertensive rat

Adrenomedullin (AM) is a multifunctional regulatory peptide, and endogenous AM is an important factor in regulating cardiovascular and renal homeostasis as a potent cardio-reno-protective factor. To illustrate the protective mechanism of adrenomedullin (AM) on the cardiovascular system by observing (1) the changes in mRNA and protein levels of AM and its receptor-calcitonin receptor-like receptor (CL) and receptor activity-modifying proteins (RAMPs)-in myocardia and aortas of spontaneously hypertensive rats (SHRs) and (2) the response of cardiovascular tissue to AM. The AM content and cyclic adenosine monophosphate (cAMP) production in myocardia and aortas were measured in SHRs and Wistar Kyoto (WKY) rats (11-week-old) by radioimmunoassay (RIA). The mRNA levels of brain natriuretic peptide (BNP), AM, CL, RAMP1, -2, -3 were determined by semi-quantitative RTPCR. Protein levels of CL, RAMP1, -2, -3 were assayed by Western blotting. SHRs had severe hypertension, and the tail-blood pressure was 76.7% higher, the ratio of heart weight to body weight (heart coefficient) 45.5% higher, and the BNP gene expression 4.5-fold higher than that of WKY rats (all p < 0.01). The AM-ir content in plasma, myocardia and aortas of SHRs increased by 42.5%, 68.3% and 80.4%, respectively (all p < 0.01) compared with WKY rats. Furthermore, the mRNA levels of AM, CL, RAMP1, RAMP2 and RAMP3 were elevated by 46% (p < 0.01), 62% (p < 0.05), 51.2% (p < 0.01), 41% (p < 0.01) and 54% (p < 0.01), respectively, in myocardia and by 72%, 87%, 155%, 53% and 74% (all p < 0.01), respectively, in aortas. The elevated mRNA level of CL, RAMP1 RAMP2 and RAMP3 correlated positively with that of AM mRNA in hypertrophic myocardia (r= 0.943, 0.621, 0.688 and 0.633, respectively, all p < 0.01) and aortas (r = 0.762, 0.892, 0.828 and 0.736, respectively, all p < 0.01). The protein levels of CL, RAMP1, RAMP2 and RAMP3 in myocardia and aortas of SHRs were increased compared with that of WKY rats. The response to AM was potentiated in myocardia and aortas in SHRs, and the production of cAMP was increased by 47% and 65% (both p < 0.01), respectively. AM-stimulated cAMP generation in myocardia and aortas was blocked by both AM(22-52), the specific antagonist of AM, and calcitonin gene-related peptide (CGRP)(8-37), the antagonist of the CGRP1 receptor. In myocardia and aortas of SHRs, the gene expressions and protein levels of AM, CL, RAMP1, RAMP2 and RAMP3 were increased, and the response to AM was potentiated. AM-stimulated cAMP generation in myocardia and aortas was blocked by both AM(22-52) and CGRP(8-37). The results suggest that the changes of AM and its receptors in cardiovascular tissue, and the increased response of cardiovascular tissue to AM might importantly impact the pathogenesis of hypertension.

Hypertension induced by nitric oxide synthase inhibitor increases responsiveness of ventricular myocardium and aorta of rat tissue to adrenomedullin stimulation in vitro

In this work, we aimed to observe the changes in adrenomedullin (ADM) and its receptor-calcitonin receptor-like receptor (CL), receptor activity-modifying protein (RAMP) 1, RAMP2 and RAMP3-in cardiac ventricles and aortas of hypertensive rats, and the responsiveness of injured cardiovascular tissue to ADM, then to illustrate the protective mechanism of ADM on the cardiovascular system. Male SD rats were subjected to treatment with chronic N(G)-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase. The ADM contents and cAMP production in myocardia and aortas were measured by RIA. The mRNA levels of ADM, CL, and RAMP1-3 were determined by RT-PCR. L-NNA induced severe hypertension and cardiomegaly. The ir-ADM content in plasma, ventricles and aortas in L-NNA-treated animals increased by 80%, 72% and 57% (all p<0.01), respectively. Furthermore, mRNA levels of ADM, CL, RAMP2 and RAMP3 were elevated by 91%, 33%, 50% and 72.5% (all p<0.01), respectively, in ventricles and by 95%, 177%, 74.7% and 85% (all p<0.01), respectively, in aortas. mRNA level of RAMP1 was elevated by 129% (p<0.01) in aortas but no significant difference in ventricles. The elevated mRNA levels of RAMP2 and RAMP3 were positively correlated with that of ADM in hypertrophic ventricles (r=0.633 and 0.828, p<0.01, respectively) and the elevated mRNA levels of CL, RAMP2 and RAMP3 were positively correlated with that of ADM in aortas (r=0.941, 0.943 and 0.736, all p<0.01, respectively). The response of ventricular myocardia and aortas to ADM administration potentiated, and the production of cAMP was increased by 41% and 68% (both p<0.01), respectively. ADM-stimulated cAMP generation in ventricular myocardia and aortas was blocked by administration of both ADM22-52, the specific antagonist of ADM receptor, and CGRP8-37, the antagonist of the CGRP1 receptor. The results showed an increased in cardiovascular ADM generation and an up-regulation of the gene expression of ADM and its receptor-CL, RAMP1-3 during hypertension, augmented responsiveness of ventricular myocardia and aortas of hypertensive rats to ADM, suggesting that these receptors may play a role in the cardiovascular adaptation in response to sub-chronic NO-inhibition.

Polymorphism of angiotensin converting enzyme is associated with severe circulatory compromise in febrile neutropenic children with cancer

Angiotensin converting enzyme (ACE) gene insertion(I)/deletion(D) polymorphism influences the outcome of a number of cardiovascular diseases. ACE I/D polymorphism was investigated by PCR in 207 pediatric cancer patients and 144 controls. ACE I/D distribution of patients and controls was similar. The frequency of the D allele and the prevalence of the deletion (DD) genotype were significantly (P < 0.05) higher among patients with severe circulatory compromise requiring treatment in the intensive care unit (ICU) than among the other patients and controls. Patients with the DD and ID genotypes spent significantly (P < 0.05) longer time in the ICU than patients with the II genotype.

Adrenomedullin induces heme oxygenase-1 gene expression and cGMP formation in rat vascular smooth muscle cells

Adrenomedullin (ADM) is a potent vasodilatory peptide. It regulates blood pressure by increasing cyclic adenosine monophosphate (cAMP) and guanosine-3',5'-monophosphate (cGMP). We sought to investigate the effect of ADM on heme oxygenase-1 (HO-1) gene expression and cGMP formation in cultured rat vascular smooth muscle cells (VSMCs). ADM treatment, 10(-9) and 10(-8) mol/L, increased cGMP production, and it increased the intracellular cGMP content of platelets coincubated with VSMCs. It increased cGMP content by 158.8% and 273.5%, respectively; increased HO-1 activity by 49.5% and 87%, respectively; augmented HO-1 protein levels by 66% and 126%, respectively; upregulated the steady-state level of HO-1 mRNA by 73% and 159%, respectively, and increased HO-1 mRNA transcription synthesis by four- and seven-fold, respectively. These results suggest that ADM induces HO-1 gene expression and cGMP formation in rat VSMCs.

Adrenomedullin: regulator of systemic and cardiac homeostasis in acute myocardial infarction

During and following acute myocardial infarction, a variety of endogenous mediators are elevated, one of which is adrenomedullin (AM). AM is a multifunctional peptide that has been identified as having a putative beneficial role following an ischemic insult at both systemic and local levels. Classically described as a potent vasodilator, natriuretic, and diuretic agent, experimental infarct models also demonstrate AM to exhibit antiproliferative and antiapoptotic functions in the myocardium, counterregulating the effects of mediators such as angiotensin-II and endothelin-1. Less well documented are the angiogenic and inflammatory modulating potentials of AM, which may also contribute toward reducing adverse ventricular remodeling. The review examines clinical and experimental studies, looking at the effects of AM and cellular mechanisms that could be involved in mediating cardioprotective effects and ultimately optimizing left ventricular remodeling. Finally, the possibility of enhancing endogenous actions of AM by pharmacological intervention is considered.