Changes in the renin-angiotensin-aldosterone axis in later life

Discovery, validation, and prodrug design of an ACE2 activator for treating bacterial infection-induced lung inflammation

Exacerbated inflammatory responses can be detrimental and pose fatal threats to the host, as exemplified by the global impact of the COVID-19 pandemic, resulting in millions of fatalities. Developing novel drugs to combat the damaging effects of inflammation is essential for both preventive measures and therapeutic interventions. Accumulating evidence suggests that Angiotensin Converting Enzyme 2 (ACE2) possesses the ability to optimize inflammatory responses. However, the clinical applicability of this potential is limited due to the lack of dependable ACE2 activators. In this study, we conducted a screening of an FDA-approved drug library and successfully identified a novel ACE2 activator, termed H4. The activator demonstrated the capability to mitigate lung inflammation caused by bacterial lung infections, effectively modulating neutrophil infiltration. Importantly, to improve the clinical applicability of the poorly water-soluble H4, we developed a prodrug variant with significantly enhanced water solubility while maintaining a similar level of efficacy as H4 in attenuating inflammatory responses in the lungs of mice exposed to bacterial infections. This finding highlights the potential of formulated H4 as a promising candidate for the treatment and prevention of inflammatory diseases, including lung-related conditions.

Factors Associated with the Antihypertensive Effect of Esaxerenone and Serum Potassium Elevation: A Pooled Analysis of Seven Phase III Studies

INTRODUCTION

This study investigated factors associated with the antihypertensive effects of esaxerenone and the incidence of serum potassium elevation in patients with hypertension.

METHODS

Using pooled data from seven phase III studies, the study analyzed factors associated with changes in office systolic (SBP) and diastolic (DBP) blood pressure from baseline to 12 weeks, and factors associated with incidence of serum potassium levels ≥ 5.5 mEq/L in esaxerenone-treated patients.

RESULTS

Overall, 1466 and 1472 patients were included in the full analysis and safety analysis sets, respectively. Male sex (4.02/2.40 mmHg), weight ≥ 78.4 kg (4.62/2.09 mmHg), hypertension duration ≥ 10 years (2.66/1.71 mmHg), prior antihypertensive treatment (2.38/1.40 mmHg), plasma aldosterone concentration ≥ 120 pg/mL (1.66/1.17 mmHg), urinary albumin-to-creatinine ratio (UACR) ≥ 300 mg/gCr (8.94/4.85 mmHg) or 30-299 mg/gCr (5.17/4.15 mmHg), and smoking (2.62/1.27 mmHg) were associated with mean changes in SBP and DBP. Fasting blood glucose ≥ 126 mg/dL (- 2.73 mmHg) was associated with the mean change in SBP only, and older age (65-74 years, - 2.12 mmHg; and ≥ 75 years, - 3.06 mmHg) with mean change in DBP only. Factors significantly associated with incidence of serum potassium levels ≥ 5.5 mEq/L were higher baseline serum potassium (≥ 4.5 mEq/L, odds ratio [OR] 6.702); lower estimated glomerular filtration rate (≥ 90 mL/min/1.73 m², OR 0.148; 60-89 mL/min/1.73 m², OR 0.331 vs 30-59 mL/min/1.73 m², respectively); higher UACR (30-299 mg/gCr, OR 7.317); higher DBP (≥ 100 mmHg, OR 3.248); and grade I hypertension (OR 2.168).

CONCLUSION

Esaxerenone is effective in patients with a broad range of backgrounds, though some factors may predict increased benefit. Regarding elevated serum potassium, careful therapeutic management is recommended for patients with higher baseline serum potassium and reduced renal function.

CLINICAL TRIAL REGISTRATION

UMIN000047026.

Emerging Roles for G Protein-Coupled Estrogen Receptor 1 in Cardio-Renal Health: Implications for Aging

Cardiovascular (CV) and renal diseases are increasingly prevalent in the United States and globally. CV-related mortality is the leading cause of death in the United States, while renal-related mortality is the 8th. Despite advanced therapeutics, both diseases persist, warranting continued exploration of disease mechanisms to develop novel therapeutics and advance clinical outcomes for cardio-renal health. CV and renal diseases increase with age, and there are sex differences evident in both the prevalence and progression of CV and renal disease. These age and sex differences seen in cardio-renal health implicate sex hormones as potentially important regulators to be studied. One such regulator is G protein-coupled estrogen receptor 1 (GPER1). GPER1 has been implicated in estrogen signaling and is expressed in a variety of tissues including the heart, vasculature, and kidney. GPER1 has been shown to be protective against CV and renal diseases in different experimental animal models. GPER1 actions involve multiple signaling pathways: interaction with aldosterone and endothelin-1 signaling, stimulation of the release of nitric oxide, and reduction in oxidative stress, inflammation, and immune infiltration. This review will discuss the current literature regarding GPER1 and cardio-renal health, particularly in the context of aging. Improving our understanding of GPER1-evoked mechanisms may reveal novel therapeutics aimed at improving cardio-renal health and clinical outcomes in the elderly.

Efficacy and Safety of Esaxerenone in Hypertensive Patients with Diabetic Kidney Disease: A Multicenter, Open-Label, Prospective Study

INTRODUCTION

Clinical data of esaxerenone in hypertensive patients with diabetic kidney disease (DKD) are lacking. We evaluated the efficacy and safety of esaxerenone in patients with DKD and an inadequate response to blood pressure (BP)-lowering treatment.

METHODS

In this multicenter, open-label, prospective study, patients were divided into urinary albumin-to-creatinine ratio subcohorts (UACR < 30, 30 to < 300, and 300 to < 1000 mg/gCr). Esaxerenone was initiated at 1.25 mg/day and followed by incremental dose escalation based on BP and serum potassium level monitoring. The treatment period was 12 weeks. The primary endpoint was change in morning home systolic BP/diastolic BP (SBP/DBP) from baseline to end of treatment (EOT). Secondary endpoints included achievement rate of target BP, change in UACR from baseline, and safety.

RESULTS

In total, 113 patients were enrolled. Morning home SBP/DBP significantly decreased from baseline to EOT in the total population (- 11.6/- 5.2 mmHg, both p < 0.001) and in all UACR subcohorts (all p < 0.001). The target BP achievement rate was 38.5%. Significant reductions in bedtime home and office BPs were also shown in the total population and all UACR subcohorts. UACR significantly improved from baseline to EOT in the total (- 50.9%, p < 0.001) and all UACR subcohorts (all p < 0.001). Incidence of serum potassium elevation as drug-related treatment emergent adverse events was 2.7%. The change from baseline in estimated glomerular filtration rate (eGFR) was - 4.8 mL/min/1.73 m².

CONCLUSION

Esaxerenone demonstrated a BP-lowering effect and improved albuminuria. The effects were consistent regardless of the severity of albuminuria without clinically relevant serum potassium elevation and eGFR reduction.

CLINICAL TRIAL REGISTRATION

jRCTs06119002.

The Effects of Acute Exposure to Prolonged Sitting, with and Without Interruption, on Peripheral Blood Pressure Among Adults: A Systematic Review and Meta-Analysis

BACKGROUND

Previous reviews have shown that exposure to acute prolonged sitting can have detrimental effects on several cardiovascular and cardiometabolic health markers. However, to date, there has been no synthesis of peripheral blood pressure data (including systolic blood pressure, diastolic blood pressure and mean arterial pressure), an important and translatable marker of cardiovascular health. Similarly, no previous study has consolidated the effects of sitting interruptions on peripheral blood pressure.

OBJECTIVES

We aimed to (1) assess the effect of exposure to acute prolonged sitting on peripheral blood pressure and (2) determine the efficacy of sitting interruption strategies as a means of offsetting any negative effects. Subgroup analyses by age and interruption modality were performed to explore heterogeneity.

DATA SOURCES

Electronic databases (PubMed, Web of Science and, SPORTDiscus) were searched from inception to March 2021. Reference lists of eligible studies and relevant reviews were also screened.

STUDY SELECTION

Inclusion criteria for objective (1) were: (i) peripheral blood pressure was assessed non-invasively in the upper limb pre-sitting and post-sitting; (ii) studies were either randomised controlled, randomised crossover or quasi-experimental pre-test vs post-test trials; (iii) the sitting period was ≥ 1 h; (iv) pre-sitting and post-sitting measures were performed in the same posture; and (v) participants were adults (aged ≥ 18 years), free of autonomic or neuromuscular dysfunction. Additional criteria for objective (2) were: (i) the interruption strategy was during the sitting period; (ii) there was an uninterrupted sitting control condition; and (iii) the interruption strategy must have involved participants actively moving their upper or lower limbs.

APPRAISAL AND SYNTHESIS METHODS

In total, 9763 articles were identified, of which 33 met inclusion criteria for objective (1). Of those articles, 22 met inclusion criteria for objective (2). Weighted mean difference (WMD), 95% confidence intervals (95% CI), and standardised mean difference (SMD) were calculated for all trials using inverse variance heterogeneity meta-analysis modelling. Standardised mean difference was used to determine the magnitude of effect, where < 0.2, 0.2, 0.5 and 0.8 were defined as trivial, small, moderate and large, respectively.

RESULTS

(1) Prolonged uninterrupted sitting resulted in trivial and small significant increases in systolic blood pressure (WMD = 3.2 mmHg, 95% CI 0.6 to 5.8, SMD = 0.14) and mean arterial pressure (WMD = 3.3 mmHg, 95% CI 2.2 to 4.4, SMD = 0.37), respectively, and a non-significant trivial increase in diastolic blood pressure. Subgroup analyses indicated that the increases in systolic blood pressure and mean arterial pressure were more pronounced in younger age groups. (2) Interrupting bouts of prolonged sitting resulted in significantly lower systolic blood pressure (WMD =  - 4.4 mmHg, 95% CI - 7.4 to - 1.5, SMD = 0.26) and diastolic blood pressure (WMD =  - 2.4 mmHg, 95% CI - 4.5 to - 0.3, SMD = 0.19) compared with control conditions, particularly when using aerobic interruption strategies.

CONCLUSIONS

Exposure to acute prolonged uninterrupted sitting results in significant increases in systolic blood pressure and mean arterial pressure, particularly in younger age groups. Regularly interrupting bouts of prolonged sitting, particularly with aerobic interruption strategies may reduce negative effects.

Proteomic Analysis of Longitudinal Changes in Blood Pressure

Hypertension is the leading risk factor for premature death worldwide. The identification of modifiable causes of hypertension remains an imperative task. We aimed to investigate associations between 79 proteins implicated in cardiovascular disease and longitudinal blood pressure (BP) changes in three Swedish prospective cohorts. In a discovery phase, we investigated associations between baseline circulating protein levels assessed with a proximity extension assay and BP stage progression at follow-up 5 years later among persons without BP-lowering drugs at baseline in two independent community-based cohorts from the Prospective Investigation of the Vasculature in Uppsala Seniors study (PIVUS) and the Uppsala Longitudinal Study of Adult Men (ULSAM). We used an independent cohort, the Malmö Diet and Cancer Study (MDC), for replication. The primary outcome of BP stage progression was defined as per the 2017 AHA/ACC (American Heart Association/ American College of Cardiology) Guideline BP categories. We also investigated associations of protein levels with changes in BP on a continuous scale, and meta-analyzed all three cohorts. Levels of renin were associated with BP stage progression with a 5% false discovery rate (FDR) in the ULSAM (n = 238) and PIVUS (n = 566) cohorts, but we could not replicate this association in the MDC cohort (n = 2659). The association in the discovery cohorts was modest, with an odds ratio for BP stage progression over 5 years of 1.33 (95% confidence interval 1.14 to 1.56) per standard deviation of baseline renin. In conclusion, we could not find any novel robust associations with longitudinal BP increase in a proximity extension assay-based proteomics investigation in three cohorts.

Pharmacokinetic and pharmacodynamic considerations in the treatment of the elderly patient with hypertension

INTRODUCTION

Hypertension is an important risk factor for developing cardiovascular diseases. It is more prevalent in the elderly population. Recently updated American and European guidelines recommend treating every elderly patient with hypertension independent of age, starting with a low dose of antihypertensive drugs. However, little information is available on the optimal dosages of antihypertensive drugs to treat the elderly safely. Areas covered: Comorbidities, co-medication and frailty status can alter the clinical outcome of drug treatment and can cause adverse events in the elderly. Also, due to pharmacokinetic and pharmacodynamic changes the interpatient variability when using antihypertensive drugs is considerable. In this review, an overview is given on the extent to which the previously mentioned parameters are changed in elderly patients and what this means for the exposure to antihypertensive medication. Also, recommendations on the starting dose of the most frequently used antihypertensive drugs are given based on literature data. Expert opinion: We believe that recommendations on starting dosages followed by a stepwise increase of dosages will lead to improved blood pressure control and less adverse drug reactions in the elderly patient. This may improve adherence to antihypertensive therapy.

Glucocorticoid Negative Feedback in Regulation of the Hypothalamic-Pituitary-Adrenal Axis in Rhesus Monkeys With Various Types of Adaptive Behavior: Individual and Age-Related Differences

The study of the mechanisms underlying the increased vulnerability of the individual to stressful environmental factors in different age periods is of great relevance for prevention and effective treatment of stress-dependent diseases that are widespread in the population of aging individuals. The purpose of our study was to investigate the individual and age-related features of the glucocorticoid negative feedback in regulation of the hypothalamic-pituitary-adrenal (HPA) axis, the key adaptive neuroendocrine system, in experiments with physically healthy young and old female rhesus monkeys with administration of mineracorticoid receptor (fludrocortisone) and glucocorticoid receptor (dexamethasone) agonists. We studied the monkeys with increased trait anxiety and depression-like behavior (DAB) characterized, as previously was shown, by the increased vulnerability to acute stress and the animals with normal standard behavior (SB) as the control. The pronounced individual differences in the reaction of HPA axis to fludrocortisone and dexamethasone in young animals were found. Young animals with DAB showed a lower sensitivity of HPA axis to the inhibitory effect of both fludrocortisone and dexamethasone compared with young animals with SB. At the same time, there were no significant intergroup differences in the concentration of ACTH and cortisol in response to placebo injection, i.e., in basal conditions. The old individuals with DAB demonstrated the essential relative resistance of HPA axis to fludrocortisone test and higher basal plasma levels of cortisol and ACTH in the evening (the period of HPA axis low circadian activity) compared to old SB animals. In the same time, the intergroup differences in the response of HPA axis to dexamethasone administration were leveled due to age-related increase in sensitivity of HPA axis to dexamethasone in animals with DAB. These data testify the pronounced intergroup and age differences in the feedback regulation of HPA axis, presumably resulting from unequal individual, and age-related changes in the activity of mineralcorticoid and glucocorticoid receptors in the brain structures supporting the functions of HPA axis. The maximum age disorders in functioning of the negative feedback mechanism in the regulation of HPA axis are characteristic of animals with DAB, which, apparently, underlie the increased vulnerability of these animals to stress exposure.

Role of Aldosterone and Mineralocorticoid Receptor in Cardiovascular Aging

The mineralocorticoid receptor (MR) was originally identified as a regulator of blood pressure, able to modulate renal sodium handling in response to its principal ligand aldosterone. MR is expressed in several extra-renal tissues, including the heart, vasculature, and adipose tissue. More recent studies have shown that extra-renal MR plays a relevant role in the control of cardiovascular and metabolic functions and has recently been implicated in the pathophysiology of aging. MR activation promotes vasoconstriction and acts as a potent pro-fibrotic agent in cardiovascular remodeling. Aging is associated with increased arterial stiffness and vascular tone, and modifications of arterial structure and function are responsible for these alterations. MR activation contributes to increase blood pressure with aging by regulating myogenic tone, vasoconstriction, and vascular oxidative stress. Importantly, aging represents an important contributor to the increased prevalence of cardiometabolic syndrome. In the elderly, dysregulation of MR signaling is associated with hypertension, obesity, and diabetes, representing an important cause of increased cardiovascular risk. Clinical use of MR antagonists is limited by the adverse effects induced by MR blockade in the kidney, raising the risk of hyperkalaemia in older patients with reduced renal function. Therefore, there is an unmet need for the enhanced understanding of the role of MR in aging and for development of novel specific MR antagonists in the context of cardiovascular rehabilitation in the elderly, in order to reduce relevant side effects.

Age-related hearing loss: prevention of threshold declines, cell loss and apoptosis in spiral ganglion neurons

Age-related hearing loss (ARHL) -presbycusis - is the most prevalent neurodegenerative disease and number one communication disorder of our aged population; and affects hundreds of millions of people worldwide. Its prevalence is close to that of cardiovascular disease and arthritis, and can be a precursor to dementia. The auditory perceptual dysfunction is well understood, but knowledge of the biological bases of ARHL is still somewhat lacking. Surprisingly, there are no FDA-approved drugs for treatment. Based on our previous studies of human subjects, where we discovered relations between serum aldosterone levels and the severity of ARHL, we treated middle age mice with aldosterone, which normally declines with age in all mammals. We found that hearing thresholds and suprathreshold responses significantly improved in the aldosterone-treated mice compared to the non-treatment group. In terms of cellular and molecular mechanisms underlying this therapeutic effect, additional experiments revealed that spiral ganglion cell survival was significantly improved, mineralocorticoid receptors were upregulated via post-translational protein modifications, and age-related intrinsic and extrinsic apoptotic pathways were blocked by the aldosterone therapy. Taken together, these novel findings pave the way for translational drug development towards the first medication to prevent the progression of ARHL.

The Pharmacogenomic and Metabolomic Predictors of ACE Inhibitor and Angiotensin II Receptor Blocker Effectiveness and Safety

Hypertension (HTN) is the most common chronic disease in the USA. Hypertensive patients frequently require repeat primary care visits to find an effective drug or drug combination to control their disease. Currently, patients are prescribed drugs for HTN based on race, age, and comorbidities and although the current guidelines are reasonable starting points for prescribing, 50% of hypertensive patients still fail to achieve target blood pressures. Despite numerous strategies to improve compliance, drug effectiveness, and optimization of initial drug choice, effectiveness has remained largely unchanged over the past two decades. Therefore, it is important to pursue alternative strategies to more effectively treat patients and to decrease medical costs. Additional precision medicine work is needed to identify factors associated with effectiveness of commonly used antihypertensive medications. The objective of this manuscript is to present a comprehensive review of the pharmacogenomic and metabolomic factors associated with ACEI and ARB effectiveness and safety.

Pulse wave velocity and myocardial performance index in premature ovarian insufficiency

OBJECTIVE

Epidemiological studies suggest that women with loss of ovarian function at early ages may be especially burdened by cardiovascular disease (CVD). In this study, we aimed to evaluate pulse wave velocity (PWV) and myocardial performance index (MPI) in patients with premature ovarian insufficiency (POI).

DESIGN

We enrolled 51 female patients (mean age 38.9 ± 6.7 years) with POI and 49 healthy subjects (mean age 36.8 ± 5.2 years). All participants underwent a detailed echocardiographic examination and PWV measurement, which is basically the velocity of pulse wave travelling from carotid to femoral artery.

RESULTS

Both groups were similar with regard to age, body mass index (BMI) and left ventricular ejection fraction. When diastolic functions were assessed, patients with POI had higher mean E/E'ratio (9.3 ± 1.9 vs. 7.6 ± 1.6, p < 0.001). POI patients have impaired MPI (0.9 ± 0.5 vs. 0.5 ± 0.2, p < 0.001) comparing to healthy controls but PWV measurements did not differ between two groups (5.7 ± 0.8 vs. 5.6 ± 0.6 m/s, p = 0.48).

CONCLUSIONS

This study showed POI patients might have impaired global left ventricular functions comparing to age matched healthy controls and this might reflect the effects of premature lack of estrogen (E) on women's cardiovascular (CV) system.

Aging-related impairment of urine-concentrating mechanisms correlates with dysregulation of adrenocortical angiotensin type 1 receptors in male Fischer rats

To investigate age-associated impairments in fluid homeostasis, 4-mo (young) and 32-mo (old) Fischer 344/BN male rats were studied before and after a dietary sodium load. Transferring young rats from a low-sodium (LS) to a high-sodium (HS) diet increased water intake and urine volume by 1.9- and 3.0-fold, respectively, while urine osmolality and plasma aldosterone decreased by 33 and 98%. Concomitantly, adrenocortical angiotensin type 1 receptor (AT1R) density decreased by 35%, and AT1bR mRNA decreased by 39%; no changes were observed in AT1aR mRNA. In contrast, the increase in water intake (1.4-fold) was lower in the old rats, and there was no effect of the HS diet on urine volume or urine osmolality. AT1R densities were 29% less in the old rats before transferring to the HS diet, and AT1R densities were not reduced as rapidly in response to a HS diet compared with the young animals. After 6 days on the HS diet, plasma potassium was lowered by 26% in the old rats, whereas no change was detected in the young rats. Furthermore, while plasma aldosterone was substantially decreased after 2 days on the HS diet in both young and old rats, plasma aldosterone was significantly lower in the old compared with the young animals after 2 wk on the LS diet. These findings suggest that aging attenuates the responsiveness of the adrenocortical AT1R to a sodium load through impaired regulation of AT1bR mRNA, and that this dysregulation contributes to the defects in water and electrolyte homeostasis observed in aging.

Screening for primary aldosteronism in an argentinian population: a multicenter prospective study

OBJECTIVES

Primary aldosteronism (PA) is characterized by the autonomous overproduction of aldosterone. Its prevalence has increased since the use of the aldosterone (ALD)/plasma renin activity (PRA) ratio (ARR). The objective of this study is to determine ARR and ARC (ALD/plasma renin concentration ratio) cut-off values (COV) and their diagnostic concordance (DC%) in the screening for PA in an Argentinian population.Design multicenter prospective study.

SUBJECTS AND METHODS

We studied 353 subjects (104 controls and 249 hypertensive patients). Serum aldosterone, PRA and ARR were determined. In 220 randomly selected subjects, 160 hypertensive patients and 60 controls, plasma renin concentration (PRC) was simultaneously measured and ARC was determined.

RESULTS

According to the 95th percentile of controls, we determined a COV of 36 for ARR and 2.39 for ARC, with ALD ≥ 15 ng/dL. In 31/249 hypertensive patients, ARR was ≥ 36. PA diagnosis was established in 8/31 patients (23/31 patients did not complete confirmatory tests). DC% between ARR and ARC was calculated. A significant correlation between ARR and ARC (r = 0.742; p < 0.0001) was found only with PRA > 0.3 ng/mL/h and PRC > 5 pg/mL. DC% for ARR and ARC above or below 36 and 2.39 was 79.1%, respectively.

CONCLUSION

This first Argentinian multicenter study determined a COV of 36 for ARR and 2.39 for ARC. Applying an ARR ≥ 36 in the hypertensive group, we confirmed PA in a higher percentage of patients than the previously reported one in our population. As for ARC, further studies are needed for its clinical application, since DC% is acceptable only for medium range renin values.

Hypothalamic-pituitary-adrenal (HPA) axis and aging

Human aging is associated with increasing frailty and morbidity which can result in significant disability. Dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis may contribute to aging-related diseases like depression, cognitive deficits, and Alzheimer's disease in some older individuals. In addition to neuro-cognitive dysfunction, it has also been associated with declining physical performance possibly due to sarcopenia. This article reviews the pathophysiology of HPA dysfunction with respect to increased basal adrenocorticotropic hormone (ACTH) and cortisol secretion, decreased glucocorticoid (GC) negative feedback at the level of the paraventricular nucleus (PVN) of the hypothalamus, hippocampus (HC), and prefrontal cortex (PFC), and flattening of diurnal pattern of cortisol release. It is possible that the increased cortisol secretion is secondary to peripheral conversion from cortisone. There is a decline in pregnolone secretion and C-19 steroids (DHEA) with aging. There is a small decrease in aldosterone with aging, but a subset of the older population have a genetic predisposition to develop hyperaldosteronism due to the increased ACTH stimulation. The understanding of the HPA axis and aging remains a complex area with conflicting studies leading to controversial interpretations.

Renin-angiotensin-aldosterone system and the aging kidney

Human senescence induces changes in the renin-angiotensin-aldosterone system (RAAS) which consists of a substantial decrease in its plasma activity. Consequently, the distal tubule´s capability of handling sodium and potassium is significantly reduced in the elderly, while distal tubule acidification is slightly delayed but preserved in this age group. Several studies in animal models support the hypothesis that senile renal structural changes could be induced by the local production of angiotensin II, and also that enalapril significantly decreases senile mesangial expansion, glomerulosclerosis and peritubular and medullar interstitial sclerosis. The same applies to several highly prevalent diseases in the elderly, such as hypertension, obesity, cardiac insufficiency, chronic nephropathy and dementia. In conclusion, the relationship between the RAAS and senescence is complex, since not only does aging cause many changes on this hormonal system, but also RAAS overactivity seems to be one of the main inducing mechanisms for normal senescence, and for many prevalent diseases in the elderly.

Recurrent hospitalizations with moderate to severe hyponatremia in older adults and its associated mortality

BACKGROUND

Recurrent hospitalizations with hyponatremia are commonly encountered in older adults admitted to Internal Medicine wards. However, the incidence and the prognostic implication of this phenomenon have never been studied.

METHODS

Medical charts of all older adults (≥75 years) admitted to Internal Medicine wards at a tertiary medical center during 2009-2010 with symptomatic moderate to severe hyponatremia (blood sodium ≤130 meq/l) upon admission were reviewed. The study group included patients with one or more hospitalizations with hyponatremia in the year following the first hospitalization with hyponatremia. The control group included patients with a single hospitalization with hyponatremia. Mortality rates were studied one year following the second hospitalization with hyponatremia in the study group and one year following the single hospitalization with hyponatremia in the control group. Regression analysis was used to study the association between recurrent hospitalizations with hyponatremia and 1-year mortality while controlling for demographics, chronic co-morbidities, albumin serum levels, and the number of hospitalizations.

RESULTS

The cohort included 431 older adults: 301 (69.8%) women; mean age of 84.6±5.6 years. Overall, 120 (27.8%) patients had recurrent hospitalizations with hyponatremia and 125 (29.0%) patients died within a year. 1-Year mortality rates were higher in patients with recurrent hospitalizations with hyponatremia than in patients with a single hospitalization with hyponatremia (42.5% vs. 23.8%; p<0.0001). Regression analysis showed that recurrent hospitalizations with hyponatremia were independently associated with 1-year mortality (odds ratio 1.9; 95% confidence interval 1.1-3.2; p=0.018).

CONCLUSIONS

Recurrent hospitalizations with hyponatremia in older adults are common and associated with 1-year mortality.

Emerging evidence of the importance of rapid, non-nuclear estrogen receptor signaling in the cardiovascular system

Estrogen receptors are classically known as ligand-activated transcription factors that regulate gene transcription in cells in response to hormone binding. In addition to this "genomic" signaling pathway, a "rapid, non-nuclear" signaling pathway mediated by cell membrane-associated estrogen receptors also has been recognized. Although for many years there was little evidence to support any physiological relevance of rapid-signaling, very recently evidence has been accumulating supporting the importance of the rapid, non-nuclear signaling as potentially critical for the protective effects of estrogen in the cardiovascular system. Better understanding of the rapid, non-nuclear signaling potentially provides an opportunity to design "pathway-specific" selective estrogen receptor modulators capable of differentially regulating non-nuclear vs. genomic effects that may prove useful ultimately as specific therapies for cardiovascular diseases.

Long-term re-evaluation of primary aldosteronism after medical treatment reveals high proportion of normal mineralocorticoid secretion

OBJECTIVE

In most cases of primary aldosteronism (PA), An adrenal aldosterone-secreting tumor cannot be reasonably proven, so these patients undergo medical treatment. Controversial data exist about the evolution of PA after medical therapy: long-term treatment with mineralocorticoid antagonists has been reported to normalize aldosterone levels but other authors failed to find remission of mineralocorticoid hypersecretion. Thus, we planned to retest aldosterone secretion in patients with medically treated PA diagnosed at least 3 years before.

DESIGN

Retrospective, cross-sectional study.

METHODS

The same workup for PA as at diagnosis (basal aldosterone to renin activity ratio (ARR) and aldosterone suppression test) was performed after stopping interfering drugs and low-salt diet, in 34 subjects with PA diagnosed between 3 and 15 years earlier, by case finding from subgroups of hypertensive patients at high risk for PA. Criteria for persistence of PA were the same as at diagnosis (ARR (pg/ml per ng per ml per h) >400, aldosterone >150 pg/ml basally, and >100 pg/ml after saline infusion) or less restrictive.

RESULTS

PA was not confirmed in 26 (76%) of the patients and also not in 20 (59%) using the least restrictive criteria suggested by international guidelines. Unconfirmed PA was positively associated with female sex, higher potassium levels, longer duration of hypertension, and follow-up, but not with adrenal mass, aldosterone levels at diagnosis, and treatment with mineralocorticoid antagonists.

CONCLUSIONS

This study suggests that mineralocorticoid hyperfunction in patients with PA after medical treatment may decline spontaneously. Higher potassium concentration and duration of treatment seem to increase the probability of this event.

N-acetylcysteine attenuates renal alterations induced by senescence in the rat

The aim of this study was to evaluate the effects of N-acetylcysteine (NAC) on renal function, as well as on sodium and water transporters, in the kidneys of aged rats. Normal, 8-month-old male Wistar rats were treated (n=6) or not (n=6) with NAC (600 mg/L in drinking water) and followed for 16 months. At the end of the follow-up period, we determined inulin clearance, serum thiobarbituric acid reactive substances (TBARS), serum cholesterol, and urinary phosphate excretion. In addition, we performed immunohistochemical staining for p53 and for ED-1-positive cells (macrophages/monocytes), together with Western blotting of kidney tissue for NKCC2, aquaporin 2 (AQP2), urea transporter A1 (UT-A1) and Klotho protein. At baseline, the two groups were similar in terms of creatinine clearance, proteinuria, cholesterol, and TBARS. At the end of the follow-up period, NAC-treated rats presented greater inulin clearance and reduced proteinuria, as well as lower serum cholesterol, serum TBARS, and urinary phosphate excretion, in comparison with untreated rats. In addition, NAC-treated rats showed upregulated expression of NKCC2, AQP2, and UT-A1; elevated Klotho protein expression, low p53 expression, and few ED-1 positive cells. In conclusion, we attribute these beneficial effects of NAC (the significant improvements in inulin clearance and in the expression of NKCC2, AQP2, and UT-A1) to its ability to decrease oxidative stress, inhibit p53 expression, minimize kidney inflammation, and stimulate Klotho expression.

Sexual dimorphism: the aging kidney, involvement of nitric oxide deficiency, and angiotensin II overactivity

Females develop less age-dependent loss of renal function, which may be in part due to cardiorenal protective effects of estrogens. The impact of androgen level on cardiovascular-renal health is controversial. Estrogen acts through multiple mechanisms, sometimes beneficial, sometimes damaging, which makes it difficult to predict the effect of hormone replacement therapy (HRT) in an aging population. Nitric oxide (NO) deficiency occurs in aging and contributes to age-dependent cardiovascular risk and kidney damage. The increased oxidative stress of aging has effects at multiple sites in the NO biosynthetic pathway to lower NO production/action. Loss of NO together with activated angiotensin promotes some of the decrements in cardiovascular-renal function seen with age, which may be related to actions of the sex steroids.

Could NICE guidance on the choice of blood pressure lowering drugs be simplified?

Reecha Sofat and colleagues argue that prescribing advice needs updating in the light of recent evidence that all classes of blood pressure lowering drugs are broadly equivalent

Angiotensin II type 1 receptor antagonists in the treatment of hypertension in elderly patients: focus on patient outcomes

Hypertension in the elderly is one of the main risk factors of cardiovascular and cerebrovascular diseases. Knowledge regarding the mechanisms of hypertension and specific considerations in managing hypertensive elderly through pharmacological intervention(s) is fundamental to improving clinical outcomes. Recent clinical studies in the elderly have provided evidence that angiotensin II type 1 (AT(1)) receptor antagonists can improve clinical outcomes to a similar or, in certain populations, an even greater extent than other classical arterial blood pressure-lowering agents. This newer class of antihypertensive agents presents several benefits, including potential for improved adherence, excellent tolerability profile with minimal first-dose hypotension, and a low incidence of adverse effects. Thus, AT(1) receptor antagonists represent an appropriate option for many elderly patients with hypertension, type 2 diabetes, heart failure, and/or left ventricular dysfunction.

Podocyte dysfunction in aging--related glomerulosclerosis

We review podocyte molecular structure and function, consider the underlying mechanisms related to podocyte dysfunction and propose that podocyte dysfunction be considered in the evaluation and management of age-associated glomerulosclerosis. With aging, progressive sympathetic activation, increased intrarenal renin-angiotensin system (RAS) activity, endothelin system and oxidative stress and reduced nitric oxide (NO)-availability can damage podocytes. Apoptosis and proliferation are the principal podocyte changes following injury with the latter leading to sclerosis and loss of nephrons. Podocyte loss can be evaluated by either determining their average number in biopsed glomeruli or by estimating podocyte number or their associated molecules in urine sediment. Podocyturia may be considered a marker of active glomerular disease. Preliminary data suggest that antiadrenergic drugs, angiotensin converting enzyme (ACE) inhibitors, RAS blocking drugs, endothelin system inhibitors and reduced oxidative stress can protect podocytes. Thus podocytes appear to play an important role in the pathogenesis, evaluation and therapy of age related glomerulosclerosis.

The elderly as a sensitive population in environmental exposures: making the case

The US population is aging. CDC has estimated that 20% of all Americans will be 65 or older by the year 2030. As a part of the aging process, the body gradually deteriorates and physiologic and metabolic limitations arise. Changes that occur in organ anatomy and function present challenges for dealing with environmental stressors of all kinds, ranging from temperature regulation to drug metabolism and excretion. The elderly are not just older adults, but rather are individuals with unique challenges and different medical needs than younger adults. The ability of the body to respond to physiological challenge presented by environmental chemicals is dependent upon the health of the organ systems that eliminate those substances from the body. Any compromise in the function of those organ systems may result in a decrease in the body's ability to protect itself from the adverse effects of xenobiotics. To investigate this issue, we performed an organ system-by-organ system review of the effects of human aging and the implications for such aging on susceptibility to drugs and xenobiotics. Birnbaum (1991) reported almost 20 years ago that it was clear that the pharmacokinetic behavior of environmental chemicals is, in many cases, altered during aging. Yet, to date, there is a paucity of data regarding recorded effects of environmental chemicals on elderly individuals. As a result, we have to rely on what is known about the effects of aging and the existing data regarding the metabolism, excretion, and adverse effects of prescription medications in that population to determine whether the elderly might be at greater risk when exposed to environmental substances. With increasing life expectancy, more and more people will confront the problems associated with advancing years. Moreover, although proper diet and exercise may lessen the immediate severity of some aspects of aging, the process will continue to gradually degrade the ability to cope with a variety of injuries and diseases. Thus, the adverse effects of long-term, low-level exposure to environmental substances will have a longer time to be manifested in a physiologically weakened elderly population. When such exposures are coupled with concurrent exposure to prescription medications, the effects could be devastating. Public health officials must be knowledgeable about the sensitivity of the growing elderly population, and ensure that the use of health guidance values (HGVs) for environmental contaminants and other substances give consideration to this physiologically compromised segment of the population.

Some considerations about evolution of idiopathic primary aldosteronism

The prevalence of primary aldosteronism has increased since many patients who were previously considered as being affected by low renin essential hypertension are actually satisfying the new diagnostic criteria using plasma aldosterone/ plasma renin activity (PRA) ratio. Many of these cases could be classified as subclinical hyperaldosteronism, having normal aldosterone and low PRA, or in alternative the normal range of aldosterone should be revised. Idiopathic hyperaldosteronism can, in many cases, be considered as an evolutive disease: it can be hypothesized that the biochemical picture can be preceded by essential hypertension and that, after several years, primary aldosteronism can evolve back to essential hypertension due to age-related reduced vascular and adrenal sensitivity to angiotensin II. This effect is also evident after longterm treatment with aldosterone receptors blockers and therefore it possible that aldosterone-receptors blockers are able to normalize the sensitivity of glomerulosa to angiotensin II even after long-term withdrawal. The use of aldosterone receptors blockers prevents cardiovascular complications due to local aldosterone effect at the level of endothelium and mononuclear leukocytes; therefore, these drugs should be also considered for therapy of patients with hypertension. It is not excluded that aldosterone receptor blockers could prevent the onset of idiopathic hyperaldosteronism and its complications in patients with hypertension without primary hyperaldosteronism. From all these considerations it follows that the concept of normal range of aldosterone should be revised and the use of aldosterone receptor blockers should be revisited.

Gender differences in the cardiovascular effect of sex hormones

The higher incidence of cardiovascular disease in men than in women of similar age, and the menopause-associated increase in cardiovascular disease in women, has led to speculation that gender-related differences in sex hormones have a key role in the development and evolution of cardiovascular disease. Compelling data have indicated that sex differences in vascular biology are determined not only by gender-related differences in sex steroid levels, but also by gender-specific tissue and cellular differences that mediate sex-specific responses. In this Review, we describe the sex-specific effects of estrogen and testosterone on cardiovascular risk, direct vascular effects of these sex hormones, and how these effects influence development of atherosclerosis. Cardiovascular effects of exogenous hormone administration are also discussed. Importantly, evidence has indicated that estrogens alone or in combination with progestins in postmenopausal women increase cardiovascular risk if started late after menopause, but that it possibly has beneficial cardiovascular effects in younger postmenopausal women, although data on long-term testosterone therapy are lacking. Hormone therapy should not be considered solely for primary prevention or treatment of cardiovascular disease at this time.

Potential role of progestogens in the control of adipose tissue and salt sensitivity via interaction with the mineralocorticoid receptor

Beside their role in the control of water and electrolyte homeostasis, recent data clearly indicate that aldosterone and the mineralocorticoid receptor (MR) are involved in adipocyte biology. It has been recently shown that aldosterone promotes white and brown adipocyte differentiation in vitro through specific activation of the MR. In addition, a non-epithelial pro-inflammatory role for MR activation has been recently inferred from studies on mineralocorticoid/salt administration in experimental animal models and from clinical studies. The mineralocorticoid system could hence represent a potential target for new therapeutic strategies in obesity and the metabolic syndrome. Progesterone has high affinity for the MR and is a natural antagonist of aldosterone. Differently from classic synthetic progestins, which are devoid of antimineralocorticoid properties, progesterone and new progestogens show remarkable antimineralocorticoid effects. Here, we discuss the potential role of the antimineralocorticoid properties of progestogens in the control of body weight, adipose tissue proliferation and salt sensitivity; their therapeutic use in postmenopausal women, as well as in women affected by polycystic ovary syndrome, may open new and unexpected possibilities in the treatment of related metabolic disorders.

Renin-angiotensin system inhibitors protect against age-related changes in rat liver mitochondrial DNA content and gene expression

Chronic renin-angiotensin system inhibition protects against liver fibrosis, ameliorates age-associated mitochondrial dysfunction and increases rodent lifespan. We hypothesized that life-long angiotensin-II-mediated stimulation of oxidant generation might participate in mitochondrial DNA "common deletion" formation, and the resulting impairment of bioenergetic capacity. Enalapril (10 mg/kg/d) or losartan (30 mg/kg/d) administered during 16.5 months were unable to prevent the age-dependent accumulation of rat liver mitochondrial DNA "common deletion", but attenuated the decrease of mitochondrial DNA content. This evidence - together with the enhancement of NRF-1 and PGC-1 mRNA contents - seems to explain why enalapril and losartan improved mitochondrial functioning and lowered oxidant production, since both the absolute number of mtDNA molecules and increased NRF-1 and PGC-1 transcription are positively related to mitochondrial respiratory capacity, and PGC-1 protects against increases in ROS production and damage. Oxidative stress evoked by abnormal respiratory function contributes to the pathophysiology of mitochondrial disease and human aging. If the present mitochondrial actions of renin-angiotensin system inhibitors are confirmed in humans they may modify the therapeutic significance of that strategy.

Angiotensin II in the elderly: impact of angiotensin II type 1 receptor sensitivity on peripheral hemodynamics

Exercise hyperemia is attenuated in the elderly, which may be attributed to local vasoregulatory pathways within the skeletal muscle vasculature. Therefore, we sought to determine whether healthy aging is associated with changes in angiotensin II (Ang II) receptor sensitivity through measurements of leg blood flow in resting and exercising skeletal muscle. In 12 (n=6 young, 24+/-1 years; n=6 older, 68+/-3 years) healthy volunteers, we determined changes in leg blood flow (ultrasound Doppler) before and during intra-arterial infusion of Ang II (0.8 ng/mL of leg blood flow per minute). Heart rate, arterial blood pressure, common femoral artery diameter, and mean blood velocity were measured at rest and during knee-extensor exercise at 20% and 40% of the maximal work rate (WR(max)). At rest, Ang II infusion decreased leg blood flow to a greater extent in older (-61+/-8%) subjects compared with younger subjects (-31+/-5%). Compared with rest, Ang II-mediated vasoconstriction (leg blood flow) during exercise was diminished in both older and younger subjects at 20% (older: -7+/-5%; younger: -21+/-2%) and 40% WR(max) (older: -5+/-4%; younger: -9+/-3%). These data identify a clear age-related hypersensitivity to Ang II in the resting leg, which may contribute to the recognized decrement in leg blood flow in this cohort. However, the diminished vasoconstriction to Ang II during exercise suggests that the elevation in Ang II type 1 receptor sensitivity documented at rest does not contribute significantly to the blunted exercise hyperemia experienced with advancing age.

Short- and long-term glycaemic control and the state of the renin system in type 1 diabetes mellitus

Renin system blockade in diabetes exerts a strong positive influence on complications, especially nephropathy. In hyperglycaemic diabetic subjects, however, blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors results in a marked rise in plasma renin. We investigated whether glycaemic fluctuations measured in hours, or those measured in weeks by Haemoglobin A(1C) (HbA(1C)) , influenced the plasma renin response to captopril. Fifty-four type 1 diabetic subjects were studied in high-salt balance. After an all night fast and in the supine position, baseline serum glucose level was drawn. Iv. glucose and insulin were then administered to keep serum glucose between 100 and 150 mg/dL (target). When target was reached, captopril 25 mg pre os was administered and plasma renin activity (PRA) and finger stick glucose were drawn, then serially every 45 minutes for 225 minutes. Baseline glucose and baseline PRA were drawn hours apart. Peak PRA corresponded to the renin level at peak captopril effect, 90' after administration. Renin response (RR) = peak PRA - baseline PRA. Correlation of baseline glucose with baseline PRA was weak (r=0.3, p=0.02), but strong with peak PRA (r=0.65; p=0.002). Drop in glucose had a weak, negative correlation with baseline PRA (r=-0.3, p=0.03) but a much stronger one with peak PRA (r=-0.7, p<0.0001). After adjustment for baseline PRA and baseline glucose, mean RR correlated strongly with mean drop in glucose (r=-0.72; p=0.008). Conversely, HbA1C correlated with none of the measures of renin system activation (r=0.05;p=0.7). In type 1 diabetic subjects, short-term hyperglycaemia, but not long-term glycaemic control, enhanced the RR to captopril.

Renin: friend or foe?

Renin maintains blood pressure through vasoconstriction when there is inadequate salt to maintain volume. In populations where blood pressure is more often high than low, and vascular death more common than haemorrhage or dehydration, therapeutic reductions in renin secretion or response are valuable. Whether long-term benefits are due entirely to blood pressure reduction remains unproved. The pathway can be blocked at its rate-limiting step (beta blockade or direct renin inhibition), the synthesis of the active product, angiotensin II, or at the receptor for angiotensin. Because renin and sodium are the two main factors in blood pressure control, and renin levels vary inversely with sodium load, blood pressure control requires a combination of natriuresis and blocking the consequential increase in renin activity. Being a large and stable molecule, renin is among the easiest and cheapest of hormone measurements. Understanding the simple biochemistry and physiology of renin permits optimal use of the drugs acting to raise or suppress this hormone.

Influence of aging on adrenal responsiveness in a population of eleven healthy beagles

The present study aimed at investigating the effects of aging on the adrenal cortex response of cortisol and aldosterone in dogs. A population of healthy adult Beagles was evaluated twice at a five-year interval. At each evaluation, plasma basal cortisol and aldosterone, cortisol and aldosterone following ACTH-stimulation, sodium, and potassium concentrations and arterial blood pressure were measured. We observed significantly (p<0.05) greater sodium, urea and creatinine concentrations with aging. Nevertheless urea and creatinine remained within our laboratory reference ranges. This study showed a highly significant age-related elevation of basal cortisol (p<0.01). Inversely, both aldosterone following ACTH-stimulation levels and difference between aldosterone following ACTH-stimulation and basal aldosterone values plummeted significantly (p<0.01) with aging. In conclusion, the evaluation of the adrenal cortex function in dogs should take in consideration the age of the individuals.

Renin release in response to Renin system blockade: activation of the Renin system in type 1 diabetes mellitus

Activation of the renin-angiotensin system (RAS) in diabetes is thought to contribute to nephropathy. This is suggested by findings of an enhanced renovascular (RPF) response to RAS blockade with angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin receptor blockers (ARBs). An alternative approach to assess RAS activation is the evaluation of renin release following RAS blockade. Forty-four consecutively enrolled Type 1 diabetic patients (28.2+/-1.5 years) and 37 normal subjects (37+/-2.6 years) in high salt balance were given 25 mg of captopril and 16 mg of candesartan p.o. on consecutive days. All subjects were Caucasian. All, except one diabetic patient, had normal renal function. Plasma renin activity (PRA) and renal plasma flow (RPF) were measured for four hours after both drugs, and at eight, and 24 hours after candesartan. As anticipated, both drugs increased PRA. Peak responses (90' after captopril) were 5.6+/-1 ng/mL Ang I/hour in diabetic patients, and 1.7+/-0.9 ng/mL Ang I/hour in normal subjects (p<0.001). Responses to both drugs were correlated in diabetic patients for PRA (r=0.623; p=0.001) and for RPF (r=0.9; p<0.001). When the PRA response to captopril was below the median, the RPF response was limited (22.1+/-17.6 ml/minute/1.73 m2). When it was above the median, the RPF response was also larger (62.2+/-13.9 ml/minute/1.73 m2; p=0.006). Renin response to ACE-I and ARB confirms activation of the RAS in diabetic patients.

Differential effects of aging on fluid intake in response to hypovolemia, hypertonicity, and hormonal stimuli in Munich Wistar rats

A significant proportion of aged humans may have impaired thirst and inadequate fluid intake after a period of fluid deprivation. We have studied the water drinking responses, relative to body weight, of Munich Wistar (MW) rats in response to osmotic, hypovolemic, dehydrational, and angiotensin (Ang)-related stimuli as they aged from 3 to 24 months. Young 3-months-old (m.o.) rats had the largest daily fluid intakes and drinking responses to hypertonic and dehydrational stimuli, suggesting that they have accentuated thirst in comparison with older age groups. There were no differences in daily fluid intake from 6-24 m.o.; however, drinking responses to i.p. injection of hypertonic 0.4 mol/liter NaCl gradually declined over this period so that in 24-m.o. rats the response was only half that of 6-m.o. rats. Water intake after 24-h water deprivation also declined gradually over 24 months. Drinking responses to hypovolemia induced by s.c. injection of colloid (polyethylene glycol) were unchanged in 6- to 15-m.o. rats, then declined precipitously in 18- to 24-m.o. rats. Drinking responses to s.c. Ang II or s.c. isoproterenol were not reduced in 24-m.o. rats, nor was the drinking associated with feeding. Therefore, there are specific impairments of water intake in response to hypertonicity and hypovolemia in aged MW rats, but Ang-related drinking is not reduced. Like aged humans, aged MW rats exhibit high plasma atrial natriuretic peptide levels and impaired cardiovascular reflexes that could contribute to the impairment of thirst with age.

The Role of Angiotensin II Type 1 Receptor Antagonists in Elderly Patients with Hypertension

Hypertension is a major risk factor for stroke and coronary events in elderly people and clinical trials have shown that treatment of hypertension with various drugs can result in a substantial reduction in cerebrovascular and cardiovascular events. The angiotensin II type 1 (AT1) receptor antagonists are the newest class of antihypertensive agents to be used widely in clinical practice. AT1 receptor antagonists can generally be given once-daily. They are also extremely well tolerated with minimal first-dose hypotension and an incidence of adverse effects similar to that seen with placebo. Adverse event rates are significantly lower than with other classes of antihypertensive drugs including ACE inhibitors. These factors result in improved compliance and increased rates of continuance on therapy. AT1 receptor antagonists show similar efficacy in lowering blood pressure to other classes of antihypertensive agents and their antihypertensive effect is potentiated when they are given concomitantly with low-dose thiazide diuretics. AT1 receptor antagonists are eliminated predominantly by the hepatic route but most are not subject to extensive metabolism and interactions with other drugs are uncommon. This is an advantage in the elderly, who are often receiving multiple medications which increases the risk for adverse drug interactions. Dose adjustments are not usually required in the elderly unless there is plasma volume depletion. Although plasma AT1 receptor antagonist concentrations are generally higher in the elderly than in younger subjects, this pharmacokinetic difference may be balanced by decreased activation of the circulating renin-angiotensin-aldosterone system in the elderly. Recent clinical studies in high-risk hypertensive patients with left ventricular hypertrophy or in patients with diabetic nephropathy or heart failure have demonstrated that AT1 receptor antagonists can improve clinical outcomes to a similar or sometimes greater extent than other antihypertensive agents. Many of these studies have included large numbers of older patients and have confirmed the excellent tolerability profile of these drugs. Thus, AT1 receptor antagonists should be considered as a possible first-line treatment or as a component of combination therapy in patients with type 2 diabetes mellitus and microalbuminuria or nephropathy and as an alternative or additional treatment to ACE inhibitors in patients with heart failure or left ventricular dysfunction. AT1 receptor antagonists also appear to reduce the onset of new diabetes compared with some other antihypertensive drugs. The benefits in terms of organ protection have mainly been seen in studies using higher doses of particular AT1 receptor antagonists and it is not certain at present whether these results can be extrapolated to other members of the class. As the elderly are more likely to have developed organ damage related to hypertension or to have heart failure or diabetes as concomitant conditions, AT1 receptor antagonists represent an appropriate option for many elderly patients. The main disadvantage of these drugs is the cost of the medication but this may be offset by their improved tolerability with fewer adverse reactions and thus increased compliance, resulting in better blood pressure control and fewer clinical events. Overall, AT1 receptor antagonists are well tolerated and efficacious for blood pressure-lowering when given as a single daily dose in elderly patients and have many potential benefits in high-risk hypertensive subjects.

Higher serum aldosterone correlates with lower hearing thresholds: a possible protective hormone against presbycusis

Aldosterone hormone is a mineralocorticoid secreted by adrenal gland cortex and controls serum sodium (Na(+)) and potassium (K(+)) levels. Aldosterone has a stimulatory effect on expression of sodium-potassium ATPase (Na, K-ATPase) and sodium-potassium-chloride cotransporter (NKCC) in cell membranes. In the present investigation, the relation between serum aldosterone levels and age-related hearing loss (presbycusis) and the correlation between these levels versus the degree of presbycusis in humans were examined. Serum aldosterone concentrations were compared between normal hearing and presbycusic groups. Pure-tone audiometry, transient evoked otoacoustic emissions (TEOAE), hearing in noise test (HINT) and gap detection were tested for each subject and compared to the serum aldosterone levels. A highly significant difference between groups in serum aldosterone concentrations was found (p = 0.0003, t = 3.95, df = 45). Highly significant correlations between pure-tone thresholds in both right and left ears, and HINT scores versus serum aldosterone levels were also discovered. On the contrary, no significant correlations were seen in the case of TEOAEs and gap detection. We conclude that aldosterone hormone may have a protective effect on hearing in old age. This effect is more peripheral than central, appearing to affect inner hair cells more than outer hair cells.

Heart failure and first dose hypotension after angiotensin converting enzyme inhibitors

The first-dose induced decrease in blood pressure in some patients following the administration of ACE inhibitors is a fact causing some concern among clinicians prescribing these drugs. However, an overview of clinical trials and the authors' own experience clearly point to the possibility of reducing the incidence and/or severity of first-dose hypotension. Apart from appropriate clinical measures to be taken, the choice of the ACE inhibitor seems to be of crucial importance as some (fosinopril, perindopril) produce less hypotension than others. Thus, with due circumspection, ACE inhibitors can safely retain their position as the cornerstone of the treatment of chronic heart failure.

Angiotensin II Receptor mRNA Expression and Vasoconstriction in Human Coronary Arteries: Effects of Heart Failure and Age

Angiotensin II is a potent vasoconstrictor that is implicated in the pathogenesis of hypertension, heart failure and atherosclerosis. In the present study, angiotensin II receptor mRNA expression levels were quantified by real-time polymerase chain reaction and the vasocontractile responses to angiotensin II were characterised by in vitro pharmacology in endothelium-denuded human coronary arteries. Angiotensin II type 1 (AT(1)) and type 2 (AT(2)) receptor mRNA expression levels were significantly down-regulated in arteries from patients with heart failure as compared to controls. The angiotensin II-induced vasoconstriction diminished with increasing age in patients with heart failure (r(2)=0.31, P<0.05). Also, the AT(1) receptor mRNA expression levels decreased with increasing age in patients with heart failure (r(2)=0.74, P<0.05), while no such correlation could be shown in the control group (r(2)=0.04, P=n.s.). The AT(2) receptor mRNA expression levels did not correlate with age in patients with heart failure or controls. In conclusion, the diminished angiotensin II vasoconstriction with age in heart failure patients is most likely due to a lower density of AT(1) receptors and may result from a longer period of exposure to heart failure in older patients.

The renin-angiotensin-aldosterone system and Alzheimer s disease?

Epidemiological studies from the last decade have begun to produce evidence that the perceived joint occurrence of vascular disease and Alzheimer's disease (AD), both common elderly disorders more often believed to occur by chance due to their high prevalence, may now actually have a more pathological significance. The following review discusses some of this evidence and the implications for cognitive decline and the development of AD and how a well-known cardiovascular risk factor gene, the apolipoprotein E (APOE) gene, plays a significant role in the molecular genetics of AD. It also introduces and discusses recent and compelling evidence for the involvement of another well-known cardiovascular risk factor gene, the angiotensin-converting enzyme (ACE1) gene, in the pathogenesis of AD. This role is suggested in terms of recent molecular genetic association evidence implicating the ACE1 insertion/deletion (indel) polymorphism, a more recent large haplotype study that greatly extends the ACE1 indel evidence and incorporates knowledge accrued from previous cardiovascular disease-focused ACE1 haplotype studies. Finally, this paper discusses very recent biological evidence that further supports a role for ACE1 and hypothesises a number of readily testable mechanisms by which the ACE1 enzyme and other components of the renin-angiotensin-aldosterone system may be implicated in increased risk and/or the progression of AD.

Sex and the renin angiotensin system: implications for gender differences in the progression of kidney disease

Two recognized risk factors implicated in the pathogenesis of progressive renal disease are overactivation of the renin angiotensin system and male gender. The peptide hormone, angiotensin II, produced by the renin angiotensin system cascade, plays a crucial role in maintaining blood pressure and electrolyte homeostasis. Medications that block the action of angiotensin II by either inhibiting its synthesis or by blocking its ability to bind its receptor are in wide clinical use because of their ability to significantly retard the progression of kidney disease. Analysis of data from national end-stage renal disease registries, clinical trials, and experimental animal models suggest that the progression of chronic kidney disease from several etiologies is more rapid in men than in women. In this review, we examine the data supporting the hypothesis that modulation of the activity of the renin angiotensin system by sex steroids markedly contributes to the gender differences observed in the pathophysiology of progressive kidney disease.

Interaction between the C(-344)T polymorphism of CYP11B2 and age in the regulation of blood pressure and plasma aldosterone levels: cross-sectional and longitudinal findings of the Olivetti Prospective Heart Study

OBJECTIVE

To study the interaction between the C(-344)T polymorphism and known determinants (age, body mass and dietary sodium) of blood pressure and plasma aldosterone.

DESIGN

Cross-sectional and longitudinal (1980-1995) survey of male workers in southern Italy.

SETTING

Medical centre of the Olivetti factories.

PARTICIPANTS

In 1995, the C(-344)T polymorphism was characterized in 811 untreated men. A subgroup of 280 participants already seen in 1980 was the object of longitudinal analysis.

MAIN OUTCOME MEASURES

Blood pressure, demographic, anthropometric and biochemical variables (serum and urinary electrolytes and plasma aldosterone) and frequency of the C(-344)T polymorphism.

RESULTS

In the whole population, there was no difference among genotypes for any of the variables examined. However, multiple regression showed a significant interaction between age (but not body mass or sodium intake) and genotype with regard to systolic (P = 0.03) and diastolic ( P= 0.02) pressure variability independently of covariates. Diastolic pressure increased linearly with age in carriers of the T allele (TT, P<0.001 and TC, P= 0.005), but not in CC homozygotes ( P= 0.848). In T carriers - but not in CC homozygotes - blood pressure and serum potassium increased and plasma aldosterone and serum sodium decreased across quintiles of age (P< 0.001 for all trends). In the longitudinal study, diastolic pressure increased significantly over time only in T carriers (TC+TT: +2.6 +/- 0.6, versus CC: -0.4 +/- 1.5 mmHg, P= 0.04).

CONCLUSION

Inter-individual variation of blood pressure and plasma aldosterone is affected by the interaction of C(-344)T polymorphism and ageing, thus supporting a role for this variant in mechanisms affecting blood pressure regulation.

Polymorphisms of genes encoding components of the sympathetic nervous system but not the renin-angiotensin system as risk factors for orthostatic hypotension

OBJECTIVE

The genetic background of orthostatic hypotension, an important risk factor for future cardiovascular morbidity and mortality, was investigated.

DESIGN AND METHODS

The study subjects comprised 415 community-dwelling individuals, who were free from any cardiovascular complications, aged 50 years or older (mean age 70.5 +/- 9 years). Basal systolic blood pressure (SBP) was measured twice in supine posture after resting for more than 10 min. The orthostatic change in SBP was determined at 1 min and 3 min after standing up. The maximum change in SBP after standing was determined. Orthostatic hypotension was defined as a decline in SBP greater than 20 mmHg. The polymorphisms of genes encoding components of the renin-angiotensin system and sympathetic nervous system, which play pivotal roles in postural change in blood pressure regulation, were determined.

RESULTS

There were no significant associations between the maximum change in SBP, the prevalence of orthostatic hypotension and gene polymorphisms of angiotensin-converting enzyme I/D, angiotensinogen M235T and angiotensin II type 1 receptor A1166C. On the contrary, polymorphism of the Gs protein alpha-subunit (GNAS1) T131C was significantly associated with the maximum change in SBP after standing [1.9 +/- 16 versus -3.6 +/- 16 mmHg (TT + TC versus CC), P = 0.008]. The prevalence of orthostatic hypotension was significantly different among GNAS1 genotypes (chi squared = 10.12, P = 0.011) and G-protein beta 3 subunit (GNB3) genotypes (chi squared = 6.12, P = 0.020). Multiple logistic regression analysis showed that both GNAS1 CC genotype [odds ratio (OR) = 2.79, 95% confidence interval (CI) 1.35-5.79, P = 0.006] and GNB3 C allele (OR = 1.78, 95% CI 1.06-3.00, P = 0.030) were independent risks for orthostatic hypotension.

CONCLUSIONS

These findings indicate that genes encoding sympathetic nervous components could be involved in the predisposition for orthostatic hypotension.

Endocrine response to surgical stress in three patients over 100 yr

PURPOSE

To report the change of plasma epinephrine, norepinephrine, cortisol, plasma renin activity, plasma aldosterone and plasma atrial natriuretic peptide during general anesthesia in three centenarian patients.

CLINICAL FEATURES

Three patients aged 101, 101 and 102-yr, underwent a screw fixation of femoral fracture under general anesthesia. Plasma concentrations of epinephrine, norepinephrine, cortisol, renin activity, aldosterone and atrial natriuretic peptide were measured before the induction of anesthesia, 15 min after incision and 60 min after the end of surgery. Plasma epinephrine concentrations in the three patients increased from 419, 344 and 377 pg x ml(-1) before anesthesia to 688, 534 and 478 pg x ml(-1) 15 min after skin incision. Plasma norepinephrine concentrations increased markedly from 408, 513 and 606 pg x ml(-1) before anesthesia to 2950, 1864 and 1574 pg x ml(-1) 15 min after skin incision. The cortisol response to surgery was similar to that of young adults. Plasma aldosterone and renin activity was low throughout anesthesia. Plasma atrial natriuretic peptide increased from 353, 367 and 109 pg x ml(-1) before induction to 479, 487 and 168 pg x ml(-1) 15 min after skin incision.

CONCLUSION

Plasma norepinephrine concentration in patients over 100 yr increased markedly during anesthesia, while plasma renin activity and aldosterone were lower.