FoxOs are lineage-restricted redundant tumor suppressors and regulate endothelial cell homeostasis

Since the discovery of adrenomedullin in 1993 several hundred papers have been published regarding the regulation of its secretion and the multiplicity of its actions. It has been shown to be an almost ubiquitous peptide, with the number of tissues and cell types synthesizing adrenomedullin far exceeding those that do not. In Section II of this paper we give a comprehensive review both of tissues and cell lines secreting adrenomedullin and of the mechanisms regulating gene expression. The data on circulating adrenomedullin, obtained with the various assays available, are also reviewed, and the disease states in which plasma adrenomedullin is elevated are listed. In Section III the pharmacology and biochemistry of adrenomedullin binding sites, both specific sites and calcitonin gene-related peptide (CGRP) receptors, are discussed. In particular, the putative adrenomedullin receptor clones and signal transduction pathways are described. In Section IV the various actions of adrenomedullin are discussed: its actions on cellular growth, the cardiovascular system, the central nervous system, and the endocrine system are all considered. Finally, in Section V, we consider some unresolved issues and propose future areas for research.

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Adrenomedullin, a Multifunctional Regulatory Peptide

Potassium is the most abundant cation in the intracellular fluid, and maintaining the proper distribution of potassium across the cell membrane is critical for normal cell function. Long-term maintenance of potassium homeostasis is achieved by alterations in renal excretion of potassium in response to variations in intake. Understanding the mechanism and regulatory influences governing the internal distribution and renal clearance of potassium under normal circumstances can provide a framework for approaching disorders of potassium commonly encountered in clinical practice. This paper reviews key aspects of the normal regulation of potassium metabolism and is designed to serve as a readily accessible review for the well informed clinician as well as a resource for teaching trainees and medical students.

Regulation of Potassium Homeostasis

ContextAtrial fibrillation (AF) is responsible for considerable morbidity and mortality, making identification of modifiable risk factors a priority. Increased pulse pressure, a reflection of aortic stiffness, increases cardiac load and may increase AF risk.ObjectiveTo examine relations between pulse pressure and incident AF.Design, Setting, and ParticipantsProspective, community-based observational cohort in Framingham, Mass, including 5331 Framingham Heart Study participants aged 35 years and older and initially free from AF (median age, 57 years; 55% women).Main Outcome MeasuresIncident AF.ResultsAF developed in 698 participants (13.1%) a median of 12 years after pulse pressure assessment. Cumulative 20-year AF incidence rates were 5.6% for pulse pressure of 40 mm Hg or less (25th percentile) and 23.3% for pulse pressure greater than 61 mm Hg (75th percentile). In models adjusted for age, sex, baseline and time-dependent change in mean arterial pressure, and clinical risk factors for AF (body mass index, smoking, valvular disease, diabetes, electrocardiographic left ventricular hypertrophy, hypertension treatment, and prevalent myocardial infarction or heart failure), pulse pressure was associated with increased risk for AF (adjusted hazard ratio [HR], 1.26 per 20-mm Hg increment; 95% confidence interval [CI], 1.12-1.43; P<.001). In contrast, mean arterial pressure was unrelated to incident AF (adjusted HR, 0.96 per 10-mm Hg increment; 95% CI, 0.88-1.05; P = .39). Systolic pressure was related to AF (HR, 1.14 per 20-mm Hg increment; 95% CI, 1.04-1.25; P = .006); however, if diastolic pressure was added, model fit improved and the diastolic relation was inverse (adjusted HR, 0.87 per 10-mm Hg increment; 95% CI, 0.78-0.96; P = .01), consistent with a pulse pressure effect. Among patients with interpretable echocardiographic images, the association between pulse pressure and AF persisted in models that adjusted for baseline left atrial dimension, left ventricular mass, and left ventricular fractional shortening (adjusted HR, 1.23; 95% CI, 1.09-1.39; P = .001).ConclusionPulse pressure is an important risk factor for incident AF in a community-based sample. Further research is needed to determine whether interventions that reduce pulse pressure will limit the growing incidence of AF.

https://jamanetwork.com/journals/jama/articlepdf/205664/joc70008_709_715.pdf

Pulse pressure and risk of new-onset atrial fibrillation

Renin and angiotensin

Adrenomedullin (AM) is a vasodilator peptide having a wide range of biological actions such as reduction of oxidative stress and inhibition of endothelial cell apoptosis. The AM gene is expressed in vascular walls, and AM was found to be secreted from cultured vascular endothelial cells, smooth muscle cells, and adventitial fibroblasts. Plasma AM levels in patients with arteriosclerotic vascular diseases are elevated in possible association with the severity of the disease. When administered over a relatively short period, AM dilates blood vessels via an endothelium-dependent or independent mechanism. Experiments in vitro have shown that AM exerts multiple actions on cultured vascular cells, which are mostly protective or inhibitory against vascular damage and progression of arteriosclerosis. Either prolonged infusion or overexpression of AM suppressed intimal thickening, fatty streak formation, and perivascular hyperplasia in rodent models for vascular remodeling or atherosclerosis. Intimal thickening induced by periarterial cuff was more severe in AM gene-knockout mice than their littermates, suggesting a protective role for endogenous AM. Moreover, AM has recently been suggested to possess angiogenetic properties. Collectively, a body of evidence suggests that AM participates in the mechanism against progression of vascular damage and remodeling, thereby alleviating the ischemia of tissues and organs.

Adrenomedullin: a protective factor for blood vessels.

Adrenomedullin (AM) and atrial and brain natriuretic peptides (ANP and BNP) exert vasodilator and natriuretic actions and are thought to share roles in counteracting the progression of hypertension or heart failure as circulating or locally-acting hormones. However, little data is available with regard to their roles in subjects who have no apparent cardiovascular diseases. The present study was carried out to identify the factors that affect plasma levels of AM, ANP and BNP in the general population. We measured the plasma levels of AM, ANP and BNP in 184 local residents who had a scheduled regular health checkup, and compared the findings with those for other clinical parameters. Univariate analyses showed that the plasma levels of AM, ANP and BNP were significantly correlated with age. The plasma levels of ANP and BNP were also significantly correlated with systolic blood pressure (SBP) and with pulse pressure (PP), an indicator of the stiffness of the great vessels. Multivariate analyses conducted using a stepwise method revealed that age was a significant, independent variable for the plasma levels of AM, ANP and BNP. In addition, PP was a significant factor for the plasma levels of ANP and BNP, while the plasma AM was significantly associated with body mass index (BMI). Thus, the plasma levels of AM, ANP and BNP all increased in association with aging, and those of ANP and BNP increased in association with PP, suggesting possible relationships between the plasma levels and age-related changes in the cardiovascular system. (Hypertens Res 2002; 25: 887-892)

Plasma Levels of Adrenomedullin and Atrial and Brain Natriuretic Peptides in the General Population: Their Relations to Age and Pulse Pressure

Adrenomedullin (AM), a potent vasodilator and natriuretic peptide, is found in human blood. To investigate the pathophysiological role of AM in essential and malignant hypertension (EHT and MHT), we measured the plasma concentrations of AM in patients with EHT of WHO stage I or II (n = 42) and in those with MHT (n = 9) by a specific radioimmunoassay, and compared these concentrations with those in normotensive controls (n = 46). The plasma concentrations of atrial and brain natriuretic peptides (ANP and BNP) in these subjects were also measured by immunoradiometric assays, and their relations to plasma AM were examined. The plasma AM level in the EHT patients (7.15+/-0.21 pmol/l, mean+/-SEM) was significantly (p < 0.01) higher than that in the normotensive controls (6.14+/-0.25 pmol/l), and a further elevation was observed in the MHT patients (14.1+/-3.8 pmol/l). Similar elevations of plasma ANP and BNP were seen in the two patient groups. The plasma AM level significantly (p < 0.01) correlated with not only the systolic (r = 0.44) and diastolic (r = 0.46) blood pressures, but also with the plasma levels of ANP (r = 0.43) and BNP (r = 0.43). The elevated plasma concentration of AM in the MHT patients decreased significantly (p < 0.05) after antihypertensive treatment, and the plasma ANP and BNP levels similarly declined. These results suggest that AM may participate, along with ANP and BNP, in mechanisms counteracting a further elevation of blood pressure in patients with EHT and MHT.

Plasma adrenomedullin and natriuretic peptides in patients with essential or malignant hypertension.

Guanylin and uroguanylin are intestinal peptides that stimulate guanylate cyclase C and cause chloride secretion. These peptides show topological instability due to two disulfide bonds. The disulfi...

https://www.physiology.org/doi/pdf/10.1152/ajpgi.1999.277.5.G960

Marked increase of guanylin secretion in response to salt loading in the rat small intestine

Aims The present study investigates the expression and localization of interleukin (IL)-10, an important anti-inflammatory cytokine, in atherectomy specimens from patients with stable and unstable angina.

Methods and results Twenty-two patients with stable angina and 21 with unstable angina who underwent directional coronary atherectomy for de novo lesions were studied. The atherectomy specimens were morphologically assessed and immunohistochemically stained with antibodies for IL-10, macrophages, smooth muscle cells, and endothelial cells. The localization and immunopositive areas were evaluated using an image analysing system. Immunoreactivity for IL-10 was detected in coronary plaques, especially in macrophages. Immunopositive areas of macrophages and IL-10, as well as the incidence of thrombus formation, were significantly greater in specimens from patients with unstable angina than in those from patients with stable angina (macrophages, P <0.001; IL-10, P <0.05; thrombus formation, P <0.05; respectively). Even after adjustment, IL-10 expression and the incidence of thrombus formation were significantly greater in the unstable angina group ( P <0.05, each). The immunoreactivities for smooth muscle cells and endothelial cells did not differ between the two groups.

Conclusion IL-10 was more frequently expressed in specimens from patients with unstable angina. This finding might contribute to a better understanding of plaque instability.

Toshihiro Kita

Papers

Adrenomedullin: a protective factor for blood vessels.

Plasma Levels of Adrenomedullin and Atrial and Brain Natriuretic Peptides in the General Population: Their Relations to Age and Pulse Pressure

Plasma adrenomedullin and natriuretic peptides in patients with essential or malignant hypertension.

Marked increase of guanylin secretion in response to salt loading in the rat small intestine

Increased expression of interleukin-10 in unstable plaque obtained by directional coronary atherectomy