Effect of B-type natriuretic peptide-guided treatment of chronic heart failure on total mortality and hospitalization: an individual patient meta-analysis.

AIMS: Natriuretic peptide-guided (NP-guided) treatment of heart failure has been tested against standard clinically guided care in multiple studies, but findings have been limited by study size. We sought to perform an individual patient data meta-analysis to evaluate the effect of NP-guided treatment of heart failure on all-cause mortality. METHODS AND RESULTS: Eligible randomized clinical trials were identified from searches of Medline and EMBASE databases and the Cochrane Clinical Trials Register. The primary pre-specified outcome, all-cause mortality was tested using a Cox proportional hazards regression model that included study of origin, age (<75 or ≥75 years), and left ventricular ejection fraction (LVEF, ≤45 or >45%) as covariates. Secondary endpoints included heart failure or cardiovascular hospitalization. Of 11 eligible studies, 9 provided individual patient data and 2 aggregate data. For the primary endpoint individual data from 2000 patients were included, 994 randomized to clinically guided care and 1006 to NP-guided care. All-cause mortality was significantly reduced by NP-guided treatment [hazard ratio = 0.62 (0.45-0.86); P = 0.004] with no heterogeneity between studies or interaction with LVEF. The survival benefit from NP-guided therapy was seen in younger (<75 years) patients [0.62 (0.45-0.85); P = 0.004] but not older (≥75 years) patients [0.98 (0.75-1.27); P = 0.96]. Hospitalization due to heart failure [0.80 (0.67-0.94); P = 0.009] or cardiovascular disease [0.82 (0.67-0.99); P = 0.048] was significantly lower in NP-guided patients with no heterogeneity between studies and no interaction with age or LVEF. CONCLUSION: Natriuretic peptide-guided treatment of heart failure reduces all-cause mortality in patients aged <75 years and overall reduces heart failure and cardiovascular hospitalization.

B-type natriuretic peptide forms within the heart, coronary sinus, and peripheral circulation in humans: evidence for degradation before secretion.

BACKGROUND: The B-type natriuretic peptides (BNP and N-terminal pro-BNP) are secreted by the heart and, in the case of BNP, serve to maintain circulatory homeostasis through renal and vascular actions and oppose many effects of the renin-angiotensin system. Recent evidence suggests that in patients with severe heart failure, circulating immunoreactive BNP is made up mainly of metabolites that may have reduced bioactivity. We hypothesized that BNP may be degraded before it even leaves the heart. METHODS: Peripheral venous plasma plus atrial and ventricular tissue, obtained from explanted hearts at the time of transplantation, were collected from 3 patients with end-stage heart failure. In a separate study, plasma was collected from the coronary sinus and femoral artery of 3 separate patients undergoing cardiac catheterization. Plasma C18 reverse-phase extracts were separated on reverse-phase HPLC, and the collected fractions were subjected to RIAs with highly specific antisera directed to the amino- and carboxy-terminal ends of BNP(1-32). RESULTS: ProBNP, BNP(1-32), and 2 major BNP metabolites were present in atrial and ventricular tissue, where BNP(1-32) represented 45% and 70% of total processed BNP, respectively. Neither BNP(1-32) nor the 2 metabolites were detected in peripheral venous plasma. Nor was BNP(1-32) detected in matching coronary sinus and femoral artery plasma from the 3 patients undergoing cardiac catheterization. CONCLUSIONS: BNP(1-32) is partly degraded within the hearts of patients with end-stage heart failure, and even in patients with relatively well-preserved left ventricular systolic function, only BNP metabolites enter the systemic circulation.

Haemodynamic, endocrine and renal actions of adrenomedullin 5 in an ovine model of heart failure.

AM5 (adrenomedullin 5), a newly described member of the CGRP (calcitonin gene-related peptide) family, is reported to play a role in normal cardiovascular physiology. The effects of AM5 in HF (heart failure), however, have not been investigated. In the present study, we intravenously infused two incremental doses of AM5 (10 and 100 ng/min per kg of body weight each for 90 min) into eight sheep with pacing-induced HF. Compared with time-matched vehicle control infusions, AM5 produced progressive and dose-dependent increases in left ventricular dP/dt(max) [LD (low dose), +56 mmHg/s and HD (high dose), +152 mmHg/s] and cardiac output (+0.83 l/min and +1.81 l/min), together with decrements in calculated total peripheral resistance (-9.4 mmHg/min per litre and -14.7 mmHg/min per litre), mean arterial pressure (-2.8 mmHg and -8.4 mmHg) and LAP (left atrial pressure; -2.6 mmHg and -5.6 mmHg) (all P<0.001). HD AM5 significantly raised PRA (plasma renin activity) (3.5-fold increment, P<0.001), whereas plasma aldosterone levels were unchanged over the intra-infusion period and actually fell in the post-infusion period (70% decrement, P<0.01), resulting in a marked decrease in the aldosterone/PRA ratio (P<0.01). Despite falls in LAP, plasma atrial natriuretic peptide and B-type natriuretic peptide concentrations were maintained relative to controls. AM5 infusion also induced significant increases in urine volume (HD 2-fold increment, P<0.05) and urine sodium (2.7-fold increment, P<0.01), potassium (1.7-fold increment, P<0.05) and creatinine (1.4-fold increment, P<0.05) excretion and creatinine clearance (60% increment, P<0.05). In conclusion, AM5 has significant haemodynamic, endocrine and renal actions in experimental HF likely to be protective and compensatory in this setting. These results suggest that AM5 may have potential as a therapeutic agent in human HF.

Stickiness to hydrophobic surfaces varies widely among peptides and proteins.

To determine whether there are differences in stickiness to hydrophobic surfaces among peptides and proteins under immunoassay conditions, peptides and proteins were radio-labeled with (125)I and competitive adsorption with human serum albumin (HSA) in polystyrene or polypropylene tubes was used to determine the IC (50), the concentration of HSA required to reduce the adsorption of the labeled polypeptides to 50% of maximal. Stickiness was defined as log(10)(10(9) IC (50)). Stickiness varied significantly between the labeled polypeptides (p < 0.00001) and ranged (±sem) from 0.99 ± 0.07 for angiotensin II to 5.30 ± 0.07 for tyr(0)-urocortin II. The stickiness of HSA and γ globulin was 1.62 ± 0.09 and 1.92 ± 0.05, respectively. No significant difference in stickiness between polystyrene and polypropylene was found. We conclude that some peptides are sufficiently sticky to risk adsorptive loss during sampling and analysis, and there may exist peptides so sticky that they remain uncharacterized.

B-type natriuretic peptide signal peptide circulates in human blood: evaluation as a potential biomarker of cardiac ischemia.

BACKGROUND: The diagnosis of cardiac necrosis such as myocardial infarction can be difficult and relies on the use of circulating protein markers like troponin. However, there is a clear need to identify circulating, specific biomarkers that can detect cardiac ischemia without necrosis. METHODS AND RESULTS: Using specific immunoassay and tandem mass spectrometry, we show that a fragment derived from the signal peptide of B-type natriuretic peptide (BNPsp) not only is detectable in cytosolic extracts of explant human heart tissue but also is secreted from the heart into the circulation of healthy individuals. Furthermore, plasma levels of BNPsp in patients with documented acute ST-elevation myocardial infarction (n=25) rise to peak values ( approximately 3 times higher than the 99th percentile of the normal range) significantly earlier than the currently used biomarkers myoglobin, creatine kinase-MB, and troponin. Preliminary receiver-operating characteristic curve analysis comparing BNPsp concentrations in ST-elevation myocardial infarction patients and other patient groups was positive (area under the curve=0.97; P<0.001), suggesting that further, more rigorous studies in heterogeneous chest pain patient cohorts are warranted. CONCLUSIONS: Our results demonstrate for the first time that BNPsp exists as a distinct entity in the human circulation and could serve as a new class of circulating biomarker with the potential to accelerate the clinical diagnosis of cardiac ischemia and myocardial infarction. Clinical Trial Registration- URL: http://www.anzctr.org.au. Unique identifier: ACTRN12609000040268.

Population-wide dietary sodium restriction: a cautious view.

"What I tell you three times is true"-Lewis Carroll. How many times have we been told that reducing dietary sodium intake will improve the health of whole populations? But is there adequate evidence to support this idea? Some recent studies have indicated that caution is needed. Targeting those most likely to benefit should prevent inadvertent harm and free the rest of the population from yet another nagging plea to alter their lifestyle.

Renal and cardiac function for long-term (10 year) risk stratification after myocardial infarction.

Aims To determine whether combined renal and cardiac function after acute myocardial infarction (MI) predicts 10 year mortality and heart failure (HF). Methods and results Estimated glomerular filtration rate (eGFR), plasma amino terminal pro-brain natriuretic peptide (NT-proBNP), and radionuclide ventriculography were obtained in 1063 patients with MI between 24-96 h of symptom onset. Mortality and HF were documented over follow-up of 9.3 years. Estimated GFR, NT-proBNP, and left ventricular ejection fraction (LVEF) each independently predicted 10 year mortality. Reduced eGFR (below 60 mL/min/1.73 m(2)) combined with increased NT-proBNP (above 1000 pg/mL) was associated with higher mortality rate compared with preserved eGFR together with lower NT-proBNP (60 vs. 14%, P < 0.001). Similar results for mortality were identified for eGFR combined with LVEF (dichotomized about 50%) (58 vs. 17%, P < 0.001). Corresponding analysis combining eGFR and NT-proBNP to predict HF yielded rates of 34 and 7% for high- and low-risk groups, respectively (P < 0.001). Similar risk stratification for HF was observed when combining eGFR with LVEF (35 vs. 7%, P < 0.001). Conclusion Ten year rates of mortality and HF are 5-10 times higher when lower eGFR is present together with increased NT-proBNP or depressed LVEF.

Intermedin (adrenomedullin-2): a potential protective role in human aortic endothelial cells.

BACKGROUND/AIMS: Intermedin (IMD) is a novel peptide with significant vasodilator and cardiac protective actions similar to the related peptide adrenomedullin (ADM). Unlike those of ADM the actions and expression of IMD in endothelial cells are poorly characterised. ADM expression can be increased during cardiovascular disease/stress in vitro and in vivo where it may have a role in several cardiovascular protective actions. To characterise IMD mRNA expression cultured human aortic endothelial cells (HAEC) were stressed by removing serum and bicarbonate, and the addition of hydrogen peroxide. The responses were compared to those of ADM mRNA. We also compared the effects of ADM and IMD on caspase activity and cell viability, and investigated if IMD actions could be altered by a CGRP receptor antagonist. METHODS/RESULTS: Using the cell immunoblot assay, immunoreactive IMD was shown to be secreted by HAEC. IMD mRNA expression was also detected in HAEC grown in endothelial growth media (but at markedly lower levels than that of ADM). Absence of bicarbonate, a redox-mediated regulator of endothelial response to various stresses, increased IMD mRNA and ADM mRNA expression. However IMD mRNA, but not ADM mRNA, was markedly increased over time in HAEC in conditions of cell stress including incubation with serum-free Dulbecco's modified Eagle's medium (DMEM) and in response to hydrogen peroxide (H2O2). These vigorous responses in IMD mRNA expression were further enhanced by incubation in 5% serum in DMEM without bicarbonate, but in a selective manner since ADM expression was suppressed by serum. We also observed that IMD mRNA was markedly increased and ADM mRNA suppressed in HAEC following a period of suspension and replating. Finally, we observed that IMD, like ADM, increased cell viability in HAEC in DMEM without serum but only IMD reduced caspase activity, perhaps via and a yet to be defined receptor system. CONCLUSION: HAECs express IMD mRNA and secrete IMD peptide. IMD mRNA expression is markedly dependent on metabolic conditions and is selectively regulated in a contrary fashion to ADM mRNA. IMD mRNA expression in endothelial cells is markedly sensitive to oxidative stress, and IMD peptide itself has antiapoptotic activity in human endothelial cells. Our data suggest that IMD has a different role to ADM and may perform a protective function in humans.

Ouabain, a circulating hormone secreted by the adrenals, is pivotal in cardiovascular disease. Fact or fantasy?

Substantial evidence points to the presence in human plasma of an inhibitor of the sodium/potassium pump which plays a central role in the pathophysiology of circulatory disorders, including essential hypertension. Studies from the 1980/90s claimed that this inhibitor was identical or very similar in structure to plant-derived ouabain and was synthesized by the adrenal cortex. However, the physical evidence in studies reporting isolation and identification of ouabain in human plasma appears insecure on closer examination. Additionally, reported circulating levels of immunoreactive ouabain in humans vary greatly, the ability of the human adrenal glands to secrete ouabain is questionable and the original commercial assay for measuring immunoreactive ouabain is no longer available. We submit that the position of ouabain as an endogenous, adrenally produced regulator of the sodium pump is of such importance that the current evidence needs either to put on a more secure footing or to lose its current status.

Serum 25-hydroxyvitamin D is not related to cardiac natriuretic peptide in nulliparous and lactating women.

BACKGROUND: Vitamin D deficiency is associated with heightened risk of cardiovascular disease. Potential mechanisms include involvement of vitamin D in regulation of renin-angiotensin system and manufacture and secretion of cardiac natriuretic peptides. Our aim was to document relationships between 25 hydroxyvitamin [25(OH)D] and N-terminal pro B-type natriuretic peptide (NT-proBNP) and plasma renin activity (PRA) levels and to document the effect of vitamin D administration on NT-proBNP and PRA levels in vitamin D deficient subjects. METHODS: Serum 25(OH)D, parathyroid hormone (PTH), plasma or serum NT-proBNP and PRA levels were measured at baseline in nulliparous and lactating women and after 2 months of oral vitamin D2 (2,000 IU/day or 60,000 IU/month) supplementation to lactating women. RESULTS: Baseline levels of 25(OH)D were low (<50 nmol/L) in most women whereas PRA and NT-proBNP levels were within the normal range. There were no significant correlations between baseline 25(OH)D or PTH with NT-proBNP and PRA. Vitamin D administration over a 2-month period in lactating women was associated with a decline in NT-proBNP (by 9.1 +/- 2.0 pmol/L; p < 0.001) and PRA (by 0.32 +/- 0.17 nmol/L/hr; p = 0.064). However, there were no significant correlations between the changes from baseline in 25(OH)D and either NT-proBNP (r = -0.04, p = 0.8) or PRA (r = -0.04, p = 0.8). CONCLUSION: We found no significant correlations between 25(OH)D or PTH with NT-proBNP and PRA in vitamin D deficient women. Further information is required to clarify the effects of vitamin D administration on cardiac structure and function.

Plasma aldosterone levels during hospitalization are predictive of survival post-myocardial infarction.

AIMS: Plasma aldosterone levels have been shown to be associated with adverse clinical outcomes after ST-elevation myocardial infarction (STEMI). We investigated whether aldosterone levels in patients presenting with STEMI or non-STEMI, are predictive of mortality during prolonged follow-up. METHODS AND RESULTS: Aldosterone levels were assayed in plasma taken from 583 patients within 24-96 h following acute myocardial infarction (MI). The median plasma aldosterone level was 108 pmol/L and all values were below the upper limit of the normal range (800 pmol/L) except for five patients (0.9%). Aldosterone tertile was significantly associated with increasing plasma levels of NTproBNP (N-terminal pro-B-type natriuretic peptide), BNP (B-type natriuretic peptide), epinephrine, and endothelin-1 (P or=25.3% mortality, P >or= 0.026). CONCLUSION: Plasma aldosterone levels post-MI are independent predictors of survival and hospitalization for heart failure over a 5-year-follow-up period.

Urocortin 1 exhibits potent inhibition of cardiac sympathetic nerve activity in conscious sheep.

OBJECTIVES: Urocortin 1 (Ucn1) and the sympathetic nervous system both participate in cardiac and circulatory regulation, but little is known about their possible interactions. METHODS: We report the effects of Ucn1 on the cardiac sympathetic nerve activity (CSNA), haemodynamics and plasma catecholamines in normal sheep. RESULTS: Bolus intravenous administration of Ucn1 at 2.5 and 10 microg in seven sheep had no significant effect on haemodynamic parameters, including heart rate, mean arterial pressure (MAP) and cardiac output. At these doses, however, Ucn1 administration reduced CSNA, with burst frequency (P = 0.011), burst incidence (P = 0.015) and burst area (P = 0.012) all significantly reduced in a dose-related manner compared with a time-matched control. At higher doses (25 and 100 microg; n = 5 sheep), Ucn1 induced significant rises in heart rate (P < 0.001) and cardiac output (P = 0.03) and reduced peripheral resistance (P = 0.03), but had no effect on MAP. Ucn1 administration at the higher doses reduced CSNA, with burst incidence (P < 0.001), burst area/min (P = 0.001) and burst area/100 beats (P < 0.001) all significantly reduced in a dose-related manner compared with a time-matched control. There was no change in plasma catecholamines at any dose. CONCLUSION: The present study shows that Ucn1 induces potent inhibition of sympathetic traffic to the heart at doses both above and below the threshold for direct actions of Ucn1 on the myocardium. These findings suggest an important role for Ucn1 in cardiovascular homeostasis and warrant further investigation for potential therapeutic applications in acute myocardial injury and heart disease.

Urocortin 2 combined with angiotensin-converting enzyme inhibition in experimental heart failure.

Ucn2 (urocortin 2) is a recently discovered peptide with therapeutic potential in heart failure. As any new treatment is likely to be used in conjunction with standard ACEI (angiotensin-converting enzyme inhibitor) therapy, it is important that the combined effects of these agents are assessed. In the present study, we investigated the effects of Ucn2 and an ACEI (captopril) administered for 3 h, both separately and together, in eight sheep with pacing-induced heart failure. Ucn2 and captopril alone both increased CO (cardiac output; Ucn2>captopril) and decreased arterial pressure (captopril>Ucn2), left atrial pressure (Ucn2>captopril) and peripheral resistance (Ucn2=captopril) relative to controls. Compared with either treatment alone, combined treatment further improved CO and reduced peripheral resistance and cardiac preload, without inducing further falls in blood pressure. In contrast with the marked increase in plasma renin activity observed with captopril alone, Ucn2 administration reduced renin activity, whereas the combined agents resulted in intermediate renin levels. All active treatments decreased circulating levels of aldosterone (Ucn2+captopril>Ucn2=captopril), endothelin-1 and the natriuretic peptides (Ucn2+captopril=Ucn2>captopril), whereas adrenaline (epinephrine) fell only with Ucn2 (Ucn2+captopril=Ucn2), and vasopressin increased during captopril alone. Ucn2, both separately and in conjunction with captopril, increased urine output, sodium and creatinine excretion and creatinine clearance. Conversely, captopril administered alone adversely affected these renal indices. In conclusion, co-treatment with Ucn2 and an ACEI in heart failure produced significantly greater improvements in haemodynamics, hormonal profile and renal function than achieved by captopril alone. These results indicate that dual treatment with these two agents is beneficial.

Regulation of endothelin-1 release from human endothelial cells by sex steroids and angiotensin-II.

It is well documented that there are gender differences in the incidence and patterns of cardiovascular disease; males have a higher incidence of cardiovascular disease than premenopausal women. We have therefore investigated whether the sex hormones, estradiol and testosterone, could directly influence the secretion of vascular peptides from human aortic endothelial cells (HAEC). Previously we have shown that testosterone can increase the number of HAECs that secrete adrenomedullin. In this study we investigated sex hormone regulation of endothelin-1 in HAEC. Several studies have observed a reduction in endothelin-1 secretion from endothelial cells in the presence of estradiol, the effect being more marked for stimulated cells. Studies on the actions of testosterone are much fewer and inconclusive. In this study we observed that estradiol did not change the number of cells secreting endothelin-1 during 4h incubation under basal conditions but decreased the number of secreting cells stimulated with angiotensin-II. Testosterone induced an increase in the number of cells secreting endothelin-1 (p=0.03). Complementary incubations revealed that testosterone up-regulated endothelin-1 mRNA at 1-3h (p<0.05). These results, together with our previous observations, indicate that angiotensin-II, testosterone and estradiol have parallel effects on the production of endothelin-1 as on adrenomedullin in HAEC. We conclude that there is potential for coordinated modulation by sex steroids and angiotensin-II of vasoactive peptide production in human endothelial cells.

Interrelationships between B-type natriuretic peptides and vitamin D in patients on maintenance peritoneal dialysis.

OBJECTIVE: Experimental evidence suggests that vitamin D deficiency impairs cardiac structure and function. Our objective was to observe relationships between circulating levels of the cardiac natriuretic peptides and vitamin D levels in patients on chronic peritoneal dialysis. METHOD: Measurements were made of circulating levels of 25-hydroxyvitamin D [25(OH)D] and plasma B-type natriuretic peptide (BNP) levels in patients receiving chronic peritoneal dialysis. RESULTS: Both BNP and the 1-76 amino-terminal fragment of pro-BNP correlated inversely with 25(OH)D levels (rs = -0.60, p = 0.007, and rs = -0.64, p = 0.003, respectively) in patients on peritoneal dialysis. CONCLUSIONS: Vitamin D deficiency in chronic renal failure may impair cardiac function, as manifested by elevated levels of B-type cardiac natriuretic peptides.

Does the hormone "endogenous ouabain" exist in the human circulation?

Studies in the early 1990s suggested that a hormone identical to ouabain or an isomer of ouabain is secreted by the adrenal glands into the circulation and plays a role in the regulation of arterial pressure and cardiac and renal function. This hormone, known as endogenous ouabain (EO), was claimed to contribute to the pathophysiology of a number of disorders including heart failure, renal failure, pregnancy-induced, and essential hypertension. However, some research groups have been unable to confirm the presence of EO in the human circulation and the issue remains in dispute. In that the implications are of considerable importance to clinicians who, like the authors, lack biochemical expertise, it would be useful if the dispute could be addressed by disinterested scientists with long-standing and acknowledged expertise in analytical chemistry who could opine as to whether the evidence is, or is not, sufficient to state categorically that EO does (or does not) exist in the circulation in man. This brief review does not present new data but, rather, recommends that adjudication is needed regarding this important issue. © 2018 BioFactors, 44(3):219-221, 2018.

Introduction of metoprolol increases plasma B-type cardiac natriuretic peptides in mild, stable heart failure.

BACKGROUND: The effect of beta-blockade on the cardiac natriuretic peptides is poorly understood but could contribute to their beneficial treatment effect and may be relevant to clinical use of plasma brain natriuretic peptide (BNP)/N-terminal pro brain natriuretic peptide (NTproBNP) measurements in risk stratification and in titration of anti-heart failure therapy. METHODS AND RESULTS: Sixteen men with mild, stable heart failure (NYHA class II to III; left ventricular ejection fraction <40%) underwent serial blood sampling for plasma natriuretic peptide levels and received infusions of atrial natriuretic peptide (ANP) and BNP before and 6 weeks after the introduction and uptitration of metoprolol or 6 weeks unchanged therapy in a randomized, parallel-group design. Plasma natriuretic peptides (BNP, NTproBNP, ANP, and NTproANP) were increased by metoprolol (P<0.01 for all). The natriuretic responses to ANP and BNP infusions were sustained with the introduction of metoprolol despite reduced renal perfusion pressure. The levels of the noninfused natriuretic peptide were increased by both ANP and BNP infusions, and this effect was enhanced by metoprolol. The early plasma half-life (t(1/2)alpha) of BNP was prolonged by metoprolol (5.6+/-0.45 to 11+/-1.3 versus 5.7+/-0.8 to 6.6+/-1.3 minutes in control subjects; P=0.019). CONCLUSIONS: Plasma cardiac natriuretic peptide levels increase significantly with the introduction of metoprolol in heart failure as a result of effects on secretion and clearance. Natriuretic responses to NP infusions are sustained with beta-blockade despite reduced renal perfusion pressure. Clinicians should be aware that the introduction of metoprolol causes a rise in plasma BNP/NTproBNP that is unrelated to deterioration in clinical status and must be considered when measurements are undertaken for risk stratification or titration of treatment.

Regulation of adrenomedullin release from human endothelial cells by sex steroids and angiotensin-II.

It is well documented that there are gender differences in the incidence and patterns of cardiovascular diseases but the reasons are unclear. Sex steroids may modulate the behaviour of vascular endothelial cells, which in turn act by paracrine processes to alter adjacent vascular smooth muscle activity. We hypothesised that the sex steroids alter the percentage of vascular endothelial cells that secrete the vasodilator peptide, adrenomedullin and modify the adrenomedullin-stimulating action of angiotensin-II. The percentage of adrenomedullin-secreting human aortic endothelial cells was determined using the cell immunoblot method. Cells were incubated with selected concentrations of angiotensin-II, oestradiol and testosterone alone and sex steroids in combination with angiotensin-II. Adrenomedullin mRNA expression in endothelial cells was quantified by real-time PCR. It was observed that at 4 h, angiotensin-II increased the percentage of adrenomedullin-secreting cells in a concentration-dependent manner. Testosterone at physiological concentrations was observed to increase the number of adrenomedullin-secreting cells whilst oestradiol had no effect. Addition of testosterone to angiotensin-II resulted in less than additive increases in the number of cells secreting adrenomedullin. Oestradiol reduced the angiotensin-II-induced increase in adrenomedullin-secreting cells. Adrenomedullin mRNA expression was significantly increased by testosterone and there was also a trend for an increase in adrenomedullin mRNA expression, which occurred when cells were incubated with angiotensin-II. Our results point to a complex interplay between the sex steroids and angiotensin-II in regulating adrenomedullin production by human endothelial cells, which may contribute to gender-related differences in vascular disease in humans.

Hypothesis: Correction of low vitamin D status among Arab women will prevent heart failure and improve cardiac function in established heart failure.

Vitamin D deficiency is common in Arab countries particularly among women. This is the result of a low dietary intake of the vitamin, limited exposure to sunlight (a paradox in view of the high sunshine figures), skin colour, obesity and high parity. Apart from its adverse effects on bone in women and their offspring, vitamin D deficiency has the potential to cause or exacerbate heart failure through a number of mechanisms including activation of the renin-angiotensin system and increased arterial pressure. Accordingly, we propose that ensuring adequate vitamin D levels in Arab women will have a much greater impact on health than just the prevention of bone disease. In particular, we suggest that prevention and correction of vitamin D deficiency will reduce the incidence of heart failure and, for Arab women with established heart failure and vitamin D deficiency, improve cardiac function.