The epidemiology of plasma renin

Sex-specific association of low-renin hypertension with metabolic and musculoskeletal health in Korean older adults

Introduction

Low-renin hypertension (LRH) accounts for approximately one-third of patients with hypertension and are more prevalent in women and the older adult population. Previous study has found a link between the renin-angiotensin-aldosterone system (RAAS) and sex hormones. However, there are insufficient data on the relationship between LRH and metabolic or musculoskeletal outcomes in older adults.

Methods and materials

Among the 343 participants from a population-based cohort study conducted between May 2018 and August 2019, a total of 256 (86 men older than 50 years and 170 postmenopausal women) were included. The presence of LRH was defined as plasma renin activity (PRA) <1 ng/mL/h and systolic blood pressure (BP) ≥130 or diastolic BP ≥80 mmHg based on the 2017 ACC/AHA guidelines. Individuals with missing data, and those who had used medications that could affect PRA within the past six months were excluded. Bone mineral density (BMD), trabecular bone score (TBS), and appendicular lean mass (ALM) index were assessed using dual-energy X-ray absorptiometry; degraded TBS was defined as partially degraded to degraded levels (≤1.350). Muscle function was assessed according to the Asian Working Group for Sarcopenia guidelines. PRA was measured using radioimmunoassay.

Results

The median age was 66 [61-72] years, and the body mass index (BMI) was 24.7 [23.0-26.4] kg/m2. Individuals with LRH, accounting for 34.8%, had lower diabetes mellitus; more dyslipidemia; and poorer muscle function, BMD, and TBS than those in the non-LRH group. In addition, PRA was positively correlated with C-peptide, HOMA-IR, TBS, and ALM index. After adjusting for covariates including age and BMI, LRH was negatively associated with femur neck T-score (adjusted β = -0.30, 95% CI [-0.55 to -0.05], p = 0.021) and the presence of LRH was significantly associated with degraded TBS in women (adjusted odds ratio = 3.00, 95% CI [1.36-6.58], p = 0.006).

Conclusion

Our findings suggest that LRH can influence clinical features and metabolic risk in older adults. Notably, LRH in postmenopausal women was linked to lower femur neck T-scores and degraded TBS, indicating sex-specific effects of LRH on bone health. Larger prospective studies are required to elucidate how changes in the RAAS affect metabolic and musculoskeletal outcomes in older adults.

Meningeal interleukin-17-producing T cells mediate cognitive impairment in a mouse model of salt-sensitive hypertension

Hypertension (HTN), a disease afflicting over one billion individuals worldwide, is a leading cause of cognitive impairment, the mechanisms of which remain poorly understood. In the present study, in a mouse model of HTN, we find that the neurovascular and cognitive dysfunction depends on interleukin (IL)-17, a cytokine elevated in individuals with HTN. However, neither circulating IL-17 nor brain angiotensin signaling can account for the dysfunction. Rather, IL-17 produced by T cells in the dura mater is the mediator released in the cerebrospinal fluid and activating IL-17 receptors on border-associated macrophages (BAMs). Accordingly, depleting BAMs, deleting IL-17 receptor A in brain macrophages or suppressing meningeal T cells rescues cognitive function without attenuating blood pressure elevation, circulating IL-17 or brain angiotensin signaling. Our data unveil a critical role of meningeal T cells and macrophage IL-17 signaling in the neurovascular and cognitive dysfunction in a mouse model of HTN.

The spectrum of low-renin hypertension

Low-renin hypertension (LRH) is a frequent condition in patients with arterial hypertension, accounting for 30% of patients. Monogenic forms can cause LRH in a minority of cases. However, in the large majority of patients, LRH is caused by the combined effects of congenital and acquired factors, comprising dietary habits. Several genetic variants have been proposed as co-factors in the pathogenesis of LRH with normal-low serum aldosterone. Emerging evidences support the hypothesis that a large proportion of LRH with normal-high serum aldosterone is associated with subclinical primary aldosteronism (PA). The recent identification of aldosterone-producing cell clusters (APCCs) as the possible cause of subclinical PA, further supported the concept of a continuous spectrum of autonomous aldosterone secretion, from subclinical forms towards overt PA. In this review we describe the main aspects of LRH, focusing on molecular basis, clinical risk profile and patients' management.

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.

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.

Quantification of systemic renin-angiotensin system peptides of hypertensive black and white African men established from the RAS-Fingerprint®

Objective:

The objective of this study was to make use of a quantitative and qualitative approach comparing the systemic renin-angiotensin system (RAS) of hypertensive black and white African men by using RAS equilibrium analysis.

Materials and methods:

This sub-study involved 23 black (n = 15) and white (n = 8) hypertensive men aged 39.5–41 years, living in the North West Province of South Africa. The RAS-Fingerprinting was determined with LC-MS/MS quantification of angiotensin peptides. Blood pressure and other variables were determined with known methods.

Results:

The main finding of this study was the significant lower Ang I (<5.0 and 45.1 pg/ml; p = 0.005) and Ang II (15.6 and 123.9 pg/ml; p ⩽ 0.001) encountered in the hypertensive black African men compared to their white counterparts. Levels of Ang 1-5 (downstream metabolite of Ang 1-7) (1.8 and 3.0 pg/ml), were detected in black and white hypertensive men, respectively.

Conclusions:

The observed differences between circulating RAS components, which are reflected via equilibrium angiotensin levels, point to a distinctive molecular regulation of the RAAS in the two study cohorts. The increased peripheral resistance observed in hypertensive black individuals might take over a dominant role in control of blood pressure in this study population. A novel highly sensitive LC-MS/MS method resolved the issue of peptide recovery variations during sample preparation by using internal standards for each individual angiotensin metabolite.

Association of renin and aldosterone with ethnicity and blood pressure: the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Although variations in plasma renin activity (PRA) and aldosterone have been examined in whites and blacks, the association of these hormones with blood pressure in multiethnic populations has not been described.

METHODS

We measured PRA and aldosterone in 1,021 participants in the Multi-Ethnic Study of Atherosclerosis not taking antihypertensives and examined the association between ethnicity and PRA/aldosterone and the association between PRA/aldosterone with systolic blood pressure (SBP).

RESULTS

Average age was 62 (SD = 9) years, and 49% of participants were women. Median PRA was 0.51 (interquartile range (IQR) = 0.29-0.87) ng/ml/hour, and median aldosterone was 12.6 (IQR = 9.1-17.1) ng/dl. After age and sex adjustment, compared with whites, blacks had 28% lower PRA and 17.4% lower aldosterone, and Hispanics had 20.1% higher PRA but similar aldosterone levels. After multivariable adjustment, compared with whites, only Hispanic ethnicity independently associated with higher PRA (0.18ng/ml/hour; 95% confidence interval (CI) = 0.06-0.31). Blacks had lower aldosterone (-1.7ng/dl; 95% CI = -3.2 to -0.2) compared with whites. After multivariable adjustment, PRA was associated with lower SBP in whites (-3.2mm Hg; 95% CI = -5.2 to -1.2 per standardized unit PRA), Chinese (-3.5mm Hg; 95% CI = -6.2 to -0.80 per standardized unit), and Hispanics (-2.3mm Hg; 95% CI = -4.1 to -0.6 per standardized unit) but not blacks. Aldosterone was associated with higher SBP only in Hispanics (2.5mm Hg; 95% CI = 0.4-4.5 per SD).

CONCLUSIONS

Compared with whites, blacks have lower aldosterone and Hispanics have higher PRA. Aldosterone had significant associations with higher SBP in Hispanics compared with other groups, a finding that may suggest a different mechanism of hypertension.

Bimodal aldosterone distribution in low-renin hypertension

BACKGROUND

In low-renin hypertension (LRH), serum aldosterone levels are higher in those subjects with primary aldosteronism and may be lower in those with non-aldosterone mineralocorticoid excess or primary renal sodium retention. We investigated the hypothesis that the frequency distribution of aldosterone in LRH is bimodal.

METHODS

Of the 3,532 attendees at the sixth examination cycle of the Framingham Offspring Study, 1,831 were included in this cross-sectional analysis after we excluded those with conditions or taking medications such as antihypertensive drugs that might affect renin or aldosterone.

RESULTS

Three hundred three subjects (17%) had untreated hypertension (SBP ≥140 mm Hg or DBP ≥90 mm Hg). LRH, defined as plasma renin ≤5 mU/L, was present in 93 of those 303 hypertensive subjects (31%). Aldosterone values were adjusted statistically for age, sex, and the urinary sodium/creatinine ratio. In the subjects with LRH, the adjusted aldosterone distribution was bimodal (dip test for unimodality, P = 0.008). The adjusted aldosterone distribution was unimodal in the normal subjects (P = 0.98) and in the hypertensive subjects with normal plasma renin (P = 0.94).

CONCLUSIONS

In this community-based sample of white subjects, those with low-renin hypertension had a bimodal adjusted aldosterone distribution. Subjects with normal-renin hypertension and subjects with normal blood pressure had unimodal adjusted aldosterone distributions. These findings suggest 2 pathophysiological variants of LRH, one that is aldosterone-dependent and one that is non-aldosterone-dependent.

End-organ damage in urbanized Africans with low plasma renin levels: the SABPA study

The purpose of this study was to evaluate whether active renin concentration is associated with markers of end-organ damage in urbanized Africans. This study forms part of the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. For this study, 81 men and 74 women were divided into low- and high-renin groups. Ambulatory blood pressure measurements were conducted. A resting 12-lead ECG was determined in order to determine the gender-specific Cornell voltage. Cardiovascular variables were continuously recorded with the Finometer. Carotid-dorsalis pedis pulse wave velocity was obtained with the Complior acquisition system. The carotid intima-media thickness (CIMT) was obtained with the SonoSite MicroMaxx. Blood samples were collected; serum and plasma were stored at -80 °C for analysis. Anthropometric measurements were taken using standard methods. A general health questionnaire was also completed. The urinary creatinine was determined with a calorimetric method and albumin with a turbidimetric method. The serum sodium and potassium were determined by making use of the Konelab TM 20i Sequential Multiple Analyzer Computer (SMAC). The concentration of active renin in the plasma was analyzed by making use of a high-sensitivity radio-immunometric assay. A negative association (r=-0.29, p<0.01) exists between renal function (ACR) and plasma renin in the low-renin group (<6.18 pg/mL), which was not observed in Africans with high-renin levels. It seems evident that low renin in black South Africans may result in sub-clinical renal damage and impaired vascular function in a group of urbanized black South Africans.

A pilot study of telmisartan for visceral adiposity in HIV infection: the metabolic abnormalities, telmisartan, and HIV infection (MATH) trial

Background

Visceral adiposity in the setting of HIV infection and antiretroviral therapy (ART) is not fully understood, and treatment options remain limited. Telmisartan, an angiotensin receptor blocker and partial PPAR-γ agonist, has been shown to decrease visceral fat and improve metabolic and inflammatory parameters in HIV-uninfected subjects.

Methods

HIV-infected subjects with HIV-1 RNA <50 copies/mL on ART and (women/men) waist circumference >94/95 cm or waist: hip ratio >0.88/0.94 received open-label telmisartan 40 mg po daily for 24 weeks. Adipose tissue (AT) volumes were quantified by L4–L5 single slice computed tomography. Metabolic and inflammatory markers were obtained fasting. Thirty-five subjects provided 80% power to detect a 10% 24-week decrease in visceral AT (VAT, two-sided α = 0.05).

Results

Thirty-five subjects enrolled and completed the protocol. At entry (median or %): age 49 years, 43% female, 77% non-white, 91% non-smokers, CD4+ T cell count 590 cells/mm³, BMI 31 kg/m². AT responses were heterogeneous, with statistically significant losses of median (IQR) total (TAT, 2.9% (−9.8, 0.7), p = 0.03) and subcutaneous (SAT, −2.7% (−9.8, 1.1), p = 0.03) AT, but not VAT (−2.7% (−20.5, 14.2), p = 0.53). Significant decreases in waist circumference and waist:hip ratio occurred (both p<0.001) without BMI or weight changes. In an exploratory analysis, significant increases in TNF-α occurred among female subjects without changes in other inflammatory or metabolic markers. No related adverse events occurred.

Conclusions

Telmisartan was well tolerated. Small losses of AT from all depots were observed after 24 weeks of telmisartan therapy. Further study is needed to determine whether HIV-infected patients can receive metabolic benefits from telmisartan.

Trial Registration

ClinicalTrials.gov NCT01088295

Review: Plasma renin and the incidence of cardiovascular disease

Whether renin is involved in the onset of coronary heart disease (CHD) remains unclear. A case-control study in 1972, suggesting a causal association between renin and CHD, has now been followed by three prospective studies. One was based on 1,717 hypertensive subjects in a Work-Site Program in New York. The main results showed an increased risk of CHD the higher the renin level. A second study in occupational groups in North West London, UK, recruited 803 white men not selected according to blood pressure, and found no association. A possible exception was in the minority of those with similar blood pressure levels to participants in the Work-Site Program, in whom the incidence of CHD was higher according to the renin level, but not significantly so. The third study was in Framingham Offspring and included 3,532 participants also not selected according to blood pressure. As in the UK study, there was no clear association between renin and risk of CHD in all participants, or in this study in those with raised blood pressure. The authors considered their results consistent with those of the UK study in finding "no association of renin with overall risk of CHD". Besides the three epidemiological studies, dealing explicitly with renin, other studies in which it has been one of several variables considered have also not found convincing evidence of its involvement in CHD. There is, therefore, little support for the hypothesis that high renin levels increase the risk of CHD, with the possible but uncertain exception of those with raised blood pressure.

Renin angiotensin system inhibition in the older person: a review

The efficacy and safety of rennin angiotensin system (RAS) inhibition for lowering blood pressure in older populations has been demonstrated in a number of clinical trials. Whether a patient's age influences the overall ability of these drugs to lower blood pressure and protect against progress of cardiovascular and kidney disease has been the focus of few clinical trials. Herein, the author's review the mechanism of action of the renin angiotensin cascade and then discuss the clinical evidence surrounding the use of RAS-blocking drugs in the older population.

Function of dynamically stimulated endothelium and renin-angiotensin-aldosterone system in normotensive subjects with a family history of hypertension

AIM

Genetic influences on the acute stimulation of the renin-angiotensin-aldosterone system (RAAS) and on endothelial activation were studied by examining healthy blood donors with and without hypertensive parents.

METHODS

Healthy blood donors were assigned to two groups, according to the presence or absence of a parental history of hypertension. Plasma levels of renin, nitric oxide (NO) and plasminogen activator inhibitor 1 (PAI-1) were studied before and after acute alterations in renal perfusion induced by phlebotomy, and the two groups compared. During phlebotomy, 400-500 mL of blood was extracted from each subject, with that volume varying relative to each subject's body surface area (m(2)).

RESULTS

No statistically significant inter-group differences were observed between the baseline mean levels of plasma renin, NO or PAI-1. After phlebotomy, significant increases were detected in mean plasma renin activity (PRA) and NO levels and in PAI-1 activity (P < 0.001). However, the increases in mean PRA (P < 0.05) level and PAI-1 activity (P < 0.05) were more pronounced in those with hypertensive parents than those without; conversely, the increase in NO levels was more pronounced in the latter group. No statistically or clinically significant difference was found between the mean body mass indices of these two groups. Only two subjects were overweight, and none were obese; the remainder had weights that were normal. We found no significant correlation between body mass index and either NO or PAI-1 level.

CONCLUSION

Post-phlebotomy, PRA and PAI-1 responses were more dramatic, but the NO response less in normotensive subjects having a parental history of hypertension, suggesting that these changes may represent familial, possibly genetic influences before overt hypertension occurs.

Factors correlated with plasma renin activity in general Japanese population

BACKGROUND

The renin-angiotensin-aldosterone system plays a pivotal role in regulation of blood pressure and electrolyte homeostasis and is a target in the treatment of hypertension and renal diseases. However, the factors correlated with plasma renin activity (PRA) are unclarified in general Japanese population. To examine this point, we conducted a community-based cross-sectional study.

METHODS

Subjects of this study were 2,056 individuals (mean age, 61 years; 934 men; 1,122 women) over 40-year-old without antihypertensive medication in Takahata town, Japan. PRA was measured by radioimmunoassay. Estimated 24-h urine sodium (e24hUNa) and potassium excretion were calculated from morning spot urine.

RESULTS

The median value of PRA was higher in men compared to women (1.1 ng/ml/h vs. 0.7 ng/ml/h, P < 0.001). The increased PRA (>2.0 ng/ml/h) were detected in 248 men (26.3%) and 142 women (12.7%). One-factor analysis of variance showed that PRA was correlated with blood pressure, uric acid, hemoglobin, total protein, total cholesterol, low-density lipoprotein cholesterol, serum adiponectin and e24hUNa in men. In women, PRA was correlated with age, blood pressure, total protein, high-density lipoprotein cholesterol (HDL-C), serum insulin, e24hUNa and obesity. Multivariate logistic regression analysis showed that high PRA (>2.0 ng/ml/h) was independently associated with low blood pressures, low e24UNa and high serum total protein both in men and women, smoking only in men and high HDL-C only in women, respectively.

CONCLUSIONS

This study revealed that PRA was higher in men than women and was associated negatively with blood pressures and urine sodium excretion, and positively with total protein, smoking and HDL-C in Japanese population.

Role of central and peripheral aminopeptidase activities in the control of blood pressure: a working hypothesis

Although there is a large body of knowledge on protein synthesis, the available data on protein catabolism, although quite substantial, are still inadequate. This is due to the marked differences in the activity of proteolytic enzymes, compounded by different substrate specificities and multiple environmental factors. Understanding enzyme behavior under physiological and pathological conditions requires the identification of specific proteolytic activities, such as aminopeptidases, as able to degrade certain peptidergic hormones or neuropeptides. Another requirement is the isolation, purification and characterization of the enzymes involved. In addition, systematic studies are needed to determine each enzyme's subcellular location, tissue distribution, and the influence of environmental factors such as diurnal rhythm, age, gender, diet, cholesterol, or steroids. Central and peripheral aminopeptidases may play a role in the control of blood pressure by coordinating the effect of the different peptides of the renin-angiotensin system cascade, acting through the AT(1), AT(2), and AT(4) receptors. Our review of the available data suggests the hypothesis that cholesterol or steroids, particularly testosterone, significantly influence aminopeptidase activities, their substrate availability and consequently their functions. These observations may have relevant clinical implications for a better understanding of the pathophysiology of cardiovascular diseases, and thus for their treatment with aminopeptidase inhibitors.

Hypertension, RAS, and gender: what is the role of aminopeptidases?

Hypertension is the major risk factor for coronary heart disease, stroke, and renal disease. Also, it is probably the most important risk factor for peripheral vascular disease and vascular dementia. Although hypertension occurs in both men and women, gender differences have been observed. However, whether sex hormones are responsible for the observed gender-associated differences in arterial blood pressure, and which is their mechanism of action, remains unclear. Local and circulating renin-angiotensin systems (RAS) are examples of systems that may be involved in the pathogenesis of hypertension. Classically, angiotensin II (Ang II) has been considered as the effector peptide of the RAS, but Ang II is not the only active peptide. Several of its degradation products, including angiotensin III (Ang III) and angiotensin IV (Ang IV) also possess biological functions. These peptides are formed via the activity of several aminopeptidases. This review will briefly summarize what is known about gender differences in RAS-regulating aminopeptidase activities, their relationship with sex hormones, and their potential role in controlling blood pressure acting through local and circulating RAS.

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.

Polymorphism in the Angiotensinogen Gene, Hypertension, and Ethnic Differences in the Risk of Recurrent Coronary Events

The M235T mutation of the human angiotensinogen gene has been shown to be associated with elevated circulating angiotensinogen concentrations and essential hypertension. The frequencies of the 235T allele are significantly different in black and white subjects. We analyzed the independent contribution of the angiotensinogen M235T mutation to the development of recurrent coronary events (coronary-related death, nonfatal myocardial infarction, or unstable angina) in a cohort of 916 black (n=145) and white (n=771) postmyocardial infarction patients who were prospectively studied during an average follow-up of 28 months. The frequency of the 235T allele was significantly higher among black (82%) than among white (44%) patients (P<0.001). There was no evidence for Hardy-Weinberg disequilibrium. During follow-up, 41 cardiac events (28%) occurred in blacks and 197 (26%) in whites (P=0.49). Multivariate Cox proportional hazards regression analysis demonstrated that 235T homozygosity was independently associated with increased risk of coronary events among black (hazard ratio: 2.37; P=0.04) but not white (hazard ratio: 0.93; P=0.68) patients, with a significant ethnic-related interaction effect (P for the difference=0.04). Among hypertensive black patients, the TT genotype was associated with a 3.3-fold (P=0.02) increase in the risk of coronary events. Our findings suggest that homozygosity for the 235T mutation in the angiotensinogen gene is an independent risk factor for coronary events in black postmyocardial infarction patients. The presence of hypertension significantly augments the risk associated with this genetic mutation.

Low-renin hypertension with relative aldosterone excess is associated with impaired NO-mediated vasodilation

Recent studies suggest that hypertension associated with low renin status and hyperaldosteronism is associated with increased risk for end-organ damage and cardiovascular events compared with other forms of hypertension. Additionally, experimental studies have demonstrated impaired nitric oxide-mediated bioactivity in these states. To investigate the relation between renin/aldosterone status and resistance vessel function, we examined plasma renin activity, serum aldosterone level, and forearm blood flow responses to the endothelium-dependent vasodilator methacholine and the endothelium-independent vasodilators sodium nitroprusside and verapamil using venous occlusion plethysmography in 130 volunteers (43 hypertensive, 87 normotensive). Low renin status was associated with impaired responses to methacholine and nitroprusside in patients with hypertension. Peak methacholine response was 8.7+/-5.6 mL/min per dL in the lowest renin quartile (0.1 to 0.3 ng/mL per hour) versus 14.3+/-7.3 mL/min per dL in the highest 3 renin quartiles combined (0.4 to 4.6 ng/mL per hour; P<0.001). Peak nitroprusside response was 5.6+/-2.3 mL/min per dL in the lowest renin quartile versus 13.3+/-4.1 mL/min per dL in the highest 3 renin quartiles combined (P<0.001). Blood pressure and other clinical characteristics were similar in all 4 quartiles. Vasodilator responses to verapamil did not relate to renin activity. Methacholine and nitroprusside responses did not relate to renin status in normotensive controls (P=0.34). Importantly, hypertensive patients with a high aldosterone/renin ratio also had impaired responses to methacholine. This study demonstrates that low-renin hypertension is associated with marked impairment of nitric oxide-mediated vasodilation of resistance vessels in the forearm vasculature of humans. This impairment could contribute to adverse outcomes in patients with low-renin hypertension and relative aldosterone excess.

Plasma sodium and hypertension

Dietary salt is the major cause of the rise in the blood pressure with age and the development of high blood pressure in populations. However, the mechanisms whereby salt intake raises the blood pressure are not clear. Existing concepts focus on the tendency for an increase in extracellular fluid volume (ECV), but an increased salt intake also induces a small rise in plasma sodium, which increases a transfer of fluid from the intracellular to the extracellular space, and stimulates the thirst center. Accordingly, the rise in plasma sodium is responsible for the tendency for an increase in ECV. Although the change in ECV may have a pressor effect, the associated rise in plasma sodium itself may also cause the blood pressure to rise. There is some evidence in patients with essential hypertension and the spontaneously hypertensive rat (SHR) that plasma sodium may be raised by 1 to 3 mmol/L. An experimental rise in sodium concentration greater than 5 mmol/L induces pressor effects on the brain and on the renin-angiotensin system. Such a rise can also induce changes in cultured vascular tissue similar to those that occur in the vessels of humans and animals on a high sodium diet, independent of the blood pressure. We suggest that a small increase in plasma sodium may be part of the mechanisms whereby dietary salt increases the blood pressure.

Links between dietary salt intake, renal salt handling, blood pressure, and cardiovascular diseases

Epidemiological, migration, intervention, and genetic studies in humans and animals provide very strong evidence of a causal link between high salt intake and high blood pressure. The mechanisms by which dietary salt increases arterial pressure are not fully understood, but they seem related to the inability of the kidneys to excrete large amounts of salt. From an evolutionary viewpoint, the human species is adapted to ingest and excrete <1 g of salt per day, at least 10 times less than the average values currently observed in industrialized and urbanized countries. Independent of the rise in blood pressure, dietary salt also increases cardiac left ventricular mass, arterial thickness and stiffness, the incidence of strokes, and the severity of cardiac failure. Thus chronic exposure to a high-salt diet appears to be a major factor involved in the frequent occurrence of hypertension and cardiovascular diseases in human populations.

Evolution of diagnostic criteria for primary aldosteronism: why is it more common in "drug-resistant" hypertension today?

The recent "epidemic" of primary aldosteronism reported in the literature is most likely related to the widespread acceptance that with easy access to accurate measurements of renin and aldosterone, it is no longer necessary to wait until hypokalemia has become profound before embarking on diagnostic testing to attempt to ferret out this most common cause of "essential" hypertension. This is especially true for those who are now classified as "drug resistant" using today's popular drugs, which are particularly ineffective in lowering blood pressure in primary aldosteronism and its variants. Understanding the physiologic consequences of a slowly increasing aldosterone production by autonomous cells will help both the family practitioner and the specialist understand the role of the aldosterone renin ratio (ARR) in the care of the hypertensive patient. In addition, the increasing number of specific genetic mutations that drive sodium retention and lead to low levels of renin activity and familial hypertension must be incorporated into the routine evaluation and care of hypertensive patients and their families.

Renal Effects

Amylin bound to kidney cortex in a distinctive pattern. Binding appeared specific in that it was displaceable with amylin antagonists. It was associated with activation of cyclic AMP (cAMP), and was thereby likely to represent receptor binding and activation. Amylin's principal effects at the kidney included a stimulation of plasma renin activity, reflected in aldosterone increases at quasi-physiological amylin concentrations. It was unclear whether this was a local or a systemic effect. Other renal effects in rats included a diuretic effect and a natriuretic effect. The latter was mainly driven by the diuresis, since urinary sodium concentration did not change. Amylin had a transient effect to lower plasma potassium concentration. This effect was likely to be a consequence of activation of Na+/K+-ATPase, an action shared with insulin and catecholamines. Amylin lowered plasma calcium, particularly ionized calcium, likely due to an antiresorptive effect at osteoclasts. Immunoreactive amylin was detected in the developing kidney. It appeared to have a trophic effect in kidney, and its absence resulted in renal dysgenesis. Neurons in the subfornical organ (SFO), which has a role in fluid/electrolyte homeostasis, were potently activated by amylin. The dipsogenic and renal effects of amylin may be related to effects at the SFO.

Association of Genetic Polymorphisms of Sodium-Calcium Exchanger 1 Gene, NCX1, with Hypertension in a Japanese General Population

The Na+/Ca2+ exchanger (NCX) is a membrane protein involved in calcium homeostasis, catalyzing the exchange of one Ca2+ ion for three Na+ ions across the cell membrane. The Na+/Ca2+ exchange has been suggested to play a role in the pathogenesis of hypertension. Therefore, we examined whether genetic variations in NCX1 were associated with hypertension. Among 15 polymorphisms identified in 96 hypertensive subjects by sequencing the entire exon and promoter regions of NCX1, 7 representative polymorphisms with a minor allele frequency of greater than 4% were genotyped in 1,865 individuals, of whom 787 were hypertensive and 1,072 were normotensive. These subjects were residents of Suita City and were randomly selected as a population for the Suita cohort study. Multivariate logistic regression analysis performed after adjusting for age, body mass index, hyperlipidemia, diabetes mellitus, smoking, and drinking revealed that the -23200T>C and -23181T>C polymorphisms in the 5' upstream region of exon 1c were significantly associated with hypertension in men (-23200T>C: CC vs. TC+TT: odds ratio=0.61; 95% confidence intervals: 0.39 to 0.97; p =0.04) and in women (-23181T>C: CC vs. TC+TT: odds ratio=1.45; 95% confidence intervals: 1.04 to 2.02; p =0.03), respectively. Thus, our study suggests that NCX1 is one of the genes related to susceptibility to essential hypertension in the Japanese general population.

A new mutation, R563Q, of the beta subunit of the epithelial sodium channel associated with low-renin, low-aldosterone hypertension

OBJECTIVE

To determine the relationship between R563Q, a mutation of the renal epithelial sodium channel, and hypertension.

METHODS

Hypertensive patients with low renin and aldosterone, hypokalemia or resistant hypertension were selected for DNA analysis. Genomic DNA encoding the C-terminal domain of the epithelial sodium channel beta subunit from hypertensives and controls was amplified by polymerase chain reaction and screened for the R563Q mutation by digestion with Sfc1 restriction enzyme, or sequenced.

RESULTS

A previously undescribed mutation, R563Q, of the beta epithelial sodium channel was found in 10 of 139 black hypertensives, but was not present in any of 103 black normotensives, a significant (P = 0.0058) difference in frequency. The frequency of the mutation in the subgroup of black low-renin, low-aldosterone hypertensives (four of 14) was significantly (P = 0.0001) greater than in normotensives, and was also greater (P = 0.041) than in normal-high renin hypertensives, suggesting that R563Q is an activating mutation of the epithelial sodium channel. R563Q was also found in seven out of 250 mixed ancestry hypertensives, and was significantly (P = 0.017) associated with low-renin, low-aldosterone hypertension in this population group. The mutation was found in one of 100 mixed ancestry normotensives but not in any of 136 white hypertensives. Of the 18 R563Q patients, 11 had severe hypertension, leading to renal failure in two cases, while only two had hypokalaemia.

CONCLUSIONS

R563Q, a new variant of the beta epithelial sodium channel, is associated with low-renin, low-aldosterone hypertension, in South African black and mixed-ancestry patients. Only a minority of individuals with the R563Q allelle fully express the Liddle's syndrome phenotype.

The neurohormonal natural history of essential hypertension: towards primary or tertiary aldosteronism?

Use of the aldosterone-to-renin ratio has controversially suggested that approximately 10% of hypertensives have primary aldosteronism, and most of these individuals are thought to have idiopathic hyperaldosteronism. The usual renin-angiotensin system control is intact in these individuals and is similar to that in low renin and essential hypertensives, differing only in the degree of sensitivity. There is recent evidence suggesting that hyperaldosteronism relates to aldosterone synthase genetic polymorphism, and also that increased angiotensin II stimulation of the adrenal glands appears to paradoxically upregulate the receptors increasing angiotensin II sensitivity. Taken together, the possibility arises that, in susceptible hypertensives, hyperaldosteronism could be acquired. Indeed, it is well known that renin-driven renovascular hypertension is associated with the development of hyperaldosteronism. Hypothetically, within the wider hypertensive population, these findings set the scene that angiotensin II adrenal sensitivity increases over time until the secretion of aldosterone becomes "autonomous" and hence "tertiary" aldosteronism in a significant proportion of hypertensives.

Both alleles of the M235T polymorphism of the angiotensinogen gene can be a risk factor for myocardial infarction

We have studied the role of three polymorphic genes of the renin-angiotensin system (RAS) as independent risk factors for myocardial infarction (MI) and their correlation with three of the major coronary risk factors: serum cholesterol (CH), hypertension (HT) and smoking (SM). A population of 392 men was genotyped for the M235T polymorphism of the angiotensinogen (AGT) gene, the insertion/deletion of the angiotensin-converting enzyme (ACE) and the all66c of the angiotensin-II type 1 receptor (AT1R), by means of polymerase chain reaction (PCR) and restriction enzyme analysis. It was observed that the T allele frequency increased significantly in the MI with HT, CH, and SM subgroup (0.58 vs 0.31) (p<0.01). In contrast, the M allele frequency was higher in the MI without HT, CH, and SM (0.69 vs 0.42) (p<0.01). A strong association between the MM genotype and MI (p<0.001, odds ratio=4.29, confidence interval=1.95-9.42) was found when age-matched MM control subjects were compared to MI individuals with none of the other known major coronary risk factors. Futhermore, subjects with the MM genotype showed a significantly higher plasma renin activity (PRA) profile than those with the TT genotype (p<0.001). It can be concluded that the M allele is an independent risk factor for MI and the T allele modified the risk when other major risk factors are present.

Angiotensin II-induced hypertension accelerates the development of atherosclerosis in apoE-deficient mice

BACKGROUND

Angiotensin II may contribute to the development and progression of atherosclerotic lesions because of its growth and proinflammatory effects. We sought to determine whether angiotensin II-induced hypertension would augment and accelerate the development of atherosclerotic lesions in apoE-deficient mice.

METHODS AND RESULTS

Angiotensin II (0.7 mg x kg(-1) x d(-1) SC) was administered to apoE-deficient mice via osmotic minipumps. The animals were placed on either standard chow or an atherogenic diet. After 8 weeks, the mean atherosclerotic lesion area in the descending thoracic and abdominal aortas of animals on a standard chow diet was 0.4+/-0.1% compared with 5.2+/-1.2% in those animals maintained on an atherogenic diet (P:<0.0001). In angiotensin II-treated animals on standard chow, the mean lesion area was increased to 11.0+/-2.3%, which was further increased to 69.9+/-9.4% (P:<0.0001) in angiotensin II-treated animals on an atherogenic diet. Similar findings were obtained when tissues from the ascending aorta were analyzed. At 8 weeks in mice receiving a standard chow diet, angiotensin II dramatically increased the atherosclerotic lesion area by 840+/-83 microm(2) (P:<0.0001). Animals on a high-fat diet had a similar marked increase in lesion area in response to angiotensin II (217+/-19 microm(2), P:<0.0001). In contrast, when hypertension was induced with norepinephrine, only a modest effect on the atherosclerotic lesion area was observed.

CONCLUSIONS

Angiotensin II-induced hypertension specifically increased the development of atherosclerosis in apoE knockout mice. This response was seen in animals receiving either standard chow or an atherogenic diet. These studies demonstrate the profound effect of angiotensin II on the development of atherosclerosis.

Glomerular hyperfiltration, high renin, and low- extracellular volume in high blood pressure

Abnormal renovascular resistance and glomerular filtration rate are characteristic of established hypertension and may also be involved in its pathogenesis. To determine renal and body fluid correlates of the predisposition to high blood pressure, we examined 100 healthy young adults with high or low blood pressure. Within each group, half had parents with high blood pressures, and half had parents with low blood pressures. Renal function and hemodynamics, body fluid volumes, and relevant hormones and genotypes were measured. Subjects with high personal and parental blood pressures had the highest levels of glomerular filtration rate (P<0.02) and plasma active renin concentration and low levels of exchangeable sodium and plasma volume (P<0.02). High glomerular filtration rate was not associated with differences in urinary kallikrein or prostaglandins. Polymorphisms of the renin, angiotensin-converting enzyme, and angiotensinogen genes were not associated with differences in glomerular filtration rate or renin. Subjects with high personal, but low parental, blood pressures had low exchangeable sodium and plasma volumes (P<0.02) but normal glomerular filtration rates. In this population, extracellular volume depletion and high renin are correlates of high blood pressure in early adulthood, and glomerular hyperfiltration is a feature of those who also have familial predisposition to high blood pressure.

Sex differences in antihypertensive drug use: determinants of the choice of medication for hypertension

OBJECTIVE

To describe and explain sex differences in antihypertensive drug use.

DESIGN AND METHODS

From 1987 to 1995, two cross-sectional population-based surveys of cardiovascular disease risk factors in The Netherlands were carried out among 56026 men and women aged 20-59 years. Polytomous logistic regression modelling was used to adjust for potential confounders of the association between sex and use of different antihypertensive drugs.

RESULTS

The response rate was 40% for men and 46% for women. Of these respondents, 40% (1041) of the hypertensive men and 59% (1403) of the hypertensive women were being treated pharmacologically; 57% (595) of the treated men and 54% (760) of the treated women were on monotherapy for hypertension with a diuretic (men 14.8%, women 37.2%), a beta-blocker (men 59.0%, women 45.3%), a calcium antagonist (men 8.6%, women 5.0%) or an angiotensin converting enzyme inhibitor (men 17.7%, women 12.5%). Among those on monotherapy for hypertension, women were less likely than men to be using a beta-blocker [prevalence odds ratio (POR), female/male=0.34; 95% confidence interval (CI) 0.24-0.47], a calcium antagonist (POR=0.27, 95% CI 0.15-0.48) or an angiotensin converting enzyme inhibitor (POR=0.34, 95% CI 0.22-0.52) than a diuretic. These sex differences persisted after adjustment for all factors that could have influenced the choice of these antihypertensive drugs (indications and contra-indications for the four antihypertensive drug classes). The sex differences in antihypertensive drug use were smaller among hypertensives with a history of cardiovascular disease (adjusted PORs, female/male, for beta-blockers, calcium antagonists and ACE inhibitors, respectively, compared to diuretics were 0.80 with 95% CI 0.20-3.24, 0.40 with 95% CI 0.10-0.48 and 0.64 with 95% CI 0.12-3.39) than among those without such a history.

CONCLUSIONS

The different patterns of antihypertensive drug use among hypertensive men and women seem irrational, and cannot be explained by factors known to influence antihypertensive drug choice. Among hypertensives with a history of cardiovascular disease, the sex differences were smaller than among those without such a history. Further research is required to explain the sex differences in the choice of antihypertensive drug by prescribers, and to investigate the consequences of these differences for long-term patient outcomes.

Sex differences and age-related changes in human serum aminopeptidase A activity

Given that aminopeptidase A is primarily responsible for cleaving aspartic acid and converting angiotensin II to angiotensin III, the purpose of the present study was to evaluate the activity of aminopeptidase A by determination of glutamate aminopeptidase activity (GluAP) and aspartate aminopeptidase activity (AspAP) (reported respectively as aminopeptidase A and angiotensinase A activities) in human serum during development and ageing, in an apparently healthy population of 139 male and 148 female subjects. To measure GluAP and AspAP we used glutamyl- and aspartyl-2-naphthylamide as substrates. Significant age-related increases were observed in GluAP activity in males and females and in AspAP activity in females. In males, there were no age-related differences in AspAP activity. A significant correlation was observed between age and GluAP activity in the population analysed as a whole or according to sex. No correlation was demonstrated between age and AspAP activity either in the whole population or according to sex. These results may reflect the evolution of the functional status of susceptible circulating substrates during development and ageing.

Association of plasma renin activity and echocardiographic left ventricular hypertrophy with frequency of new coronary events and new atherothrombotic brain infarction in older persons with systemic hypertension

In older hypertensive persons, male gender, prior coronary artery disease, prior atherothrombotic brain infarction (ABI), and echocardiographic left ventricular (LV) hypertrophy are independent risk factors for new coronary events; age, prior ABI, and echocardiographic LV hypertrophy are independent risk factors for new ABI. The data suggest that high plasma renin activity in hypertensive older persons is associated with a high risk of new coronary events and of new ABI through its association with echocardiographic LV hypertrophy.

Pharmacological manipulation of human gastrointestinal blood flow

The splanchnic circulation is one of the largest vascular regions in man. In the past, this has been difficult to study because of methodological problems. The adapting of noninvasive Doppler techniques has made it possible to develop reproducible measurements of coeliac and superior mesenteric artery blood flow, which are the main contributors to the gastrointestinal vasculature. This has resulted in the further understanding of neurogenic and humoral control of this region in a number of physiological and pathophysiological states, and has contributed towards the knowledge of its pharmacological control. These studies are of relevance to cardiovascular homeostasis and, in particular, systemic blood pressure control which depends upon various factors including responses in different vascular regions. In this review the key physiological factors which influence pharmacological studies on this circulation will be discussed. Examples will be provided, in subjects with cardiovascular and neurological disorders, of how administration of endogenous and exogenous substances, including drugs with specific pharmacological effects, alter human gastrointestinal blood flow. These will include insulin, alcohol, the somatostatin analogue octreotide, the central acting sympatholytic clonidine and the angiotensin II-converting inhibitor captopril. The relevance of these studies to subjects with postural hypotension due to sympathetic denervation and to primary hypertension, in particular, will be discussed.

Congestive heart failure in the elderly

Several aspects of congestive heart failure are discussed in the light of international literature and of recent findings of our group. The annual incidence of heart failure in elderly subjects, aged >or=75y, is 13 to 50/1000, while it is 1.6/1000 in people aged 45-54 y. The prevalence of heart failure is about 3% in subjects aged 45-64% in subjects aged more than 65 y and 10% in subjects aged more than 75 y. These data are confirmed by our population based study in elderly subjects. The etiology of congestive heart failure is similar in elderly and middle-aged patients. However, several anatomo-functional, hormonal and autonomic nervous system changes, typical of congestive heart failure, occur during physiologic ageing processes also. These findings may explain the dramatic evolution of congestive heart failure in elderly patients. Moreover, some features of the elderly - e.g. comorbidity, atypical clinical presentations, loss of autonomy, increased iatrogen risk should be considered. No specific drugs exist for the pharmacologic treatment of heart failure in the elderly, so that the geriatric specificity in the treatment of heart failure can be recognized in the art of drug choice and dosage, to obtain the best results with the least side effects. The multiple etiology of congestive heart failure, the comorbidity, the loss of autonomy and the deterioration of cognitive functions suggest the need for multidimensional approach and continuative intervention in elderly patients with heart disease, and in particular with congestive heart failure. Further studies on disease- and age-related changes are necessary to develop new and more potent strategies to secure 'successful ageing'.

Relationship of plasma renin activity with caffeine intake and physical training in mild hypertensive men. HARVEST Study Group

To study the relationship between plasma renin activity (PRA) and coffee consumption, cigarette smoking, alcohol intake and physical activity habits.

SETTING

The multicentre HARVEST trial, involving 17 Hospital Centres in Northeast Italy.

SUBJECTS

351 borderline to mild hypertensive men (mean age +/- SEM 22.7 +/- 0.47 years), never treated for hypertension.

INTERVENTIONS

Office and 24-hour blood pressure measurement, supine and standing PRA levels, and urinary catecholamines output.

MAIN OUTCOME MEASURES

PRA levels according to coffee intake and physical activity status.

RESULTS

Coffee intake showed a major effect on PRA. Supine PRA levels were 40% higher in the subjects abstaining from coffee (n = 94) than in the coffee drinkers and was similar in the moderate (n = 223) and heavy (n = 34) drinkers. A weaker negative association was found between coffee use and PRA on standing. Office and whole-day blood pressure and heart rate, and urinary catecholamines did not differ according to coffee intake. Supine PRA was lower in the subjects performing regular physical activity than in the inactive subjects. Office and whole-day diastolic blood pressure and heart rate, and urinary norepinephrine were lower in the active than in the sedentary men. No relationship was found between PRA measured either in the supine or the upright posture and tobacco or alcohol use. In a multiple linear regression model supine PRA was negatively correlated with age, coffee consumption and physical activity habits.

CONCLUSIONS

Chronic coffee intake and physical training showed an inverse relationship with PRA in mild hypertensive men, while tobacco and alcohol use were unrelated to PRA.

Characteristics and treatment of hypertension in women: a review of the literature

Although there are documented differences between women and men in frequency and severity of hypertension and in the relation between hypertension and cardiovascular risk, few studies have been designed to evaluate efficacy and safety of antihypertensive therapy in women. Efficacy of nonpharmacologic interventions to lower blood pressure may differ between the sexes; women have greater difficulty losing weight than men but may respond better than men to dietary sodium reduction. In general, women and men do not respond differently to antihypertensive therapy; however, there may be differences in response to certain classes of antihypertensives. There are limited data on safety of specific antihypertensive agents in women. In some studies, researchers found a greater incidence of adverse effects in women. Effects on sexual functioning and pharmacokinetic and pharmacodynamic characteristics of antihypertensive drugs in women have been studies inadequately. More data are needed to guide the management of hypertension in women.

Plasma renin activity and ischemic heart disease

BACKGROUND

An earlier prospective study reported an association between high levels of plasma renin activity (as measured by the renin-sodium profile) and the incidence of myocardial infarction in patients with hypertension. We have investigated the relation between plasma renin activity and ischemic heart disease in the Northwick Park Heart Study.

METHODS

The study included 803 white men 40 to 64 years of age selected from industrial workers in London. Plasma renin activity and established risk factors for ischemic heart disease were measured at entry, which was between 1972 and 1978. Ascertainment of the primary clinical end points of fatal or nonfatal myocardial infarction and sudden death from coronary causes was carried out until the end of 1991.

RESULTS

In an analysis of the 86 first coronary events, we found an independent relation between higher systolic blood pressure and coronary end points (relative risk per 1 SD increase in blood pressure, 1.47; 95 percent confidence interval, 1.16 to 1.85; P < 0.001), but no relation between plasma renin activity and coronary end points (relative risk per 1 SD increase in the level of plasma renin activity, 1.04; 95 percent confidence interval, 0.84 to 1.30). In the 242 men who had hypertension of a degree similar to that of the subjects in the earlier prospective study of the renin profile, and in whom 44 of the 86 coronary events occurred, the relative risk of those in the highest as compared with the lowest third for plasma renin activity was 1.26 (95 percent confidence interval, 0.63 to 2.56).

CONCLUSIONS

Our results suggest that there is no association between plasma renin activity and myocardial infarction or sudden death from coronary causes, at least in normotensive men.

Activation of neurohumoral systems in postinfarction left ventricular dysfunction

OBJECTIVES

This study was conducted to evaluate the degree of neurohumoral activation around the time of hospital discharge after myocardial infarction.

BACKGROUND

Because pharmacologic interventions that block the effects of neurohumoral activation improve the prognosis after infarction, we hypothesized that widespread neurohumoral activation persists in some patients until at least the time of hospital discharge and that the determinants of activation vary from one system to another.

METHODS

Five hundred nineteen patients in the Survival and Ventricular Enlargement Study (SAVE) had plasma neurohormones measured before randomization at a mean of 12 days after infarction. All patients had left ventricular dysfunction (left ventricular ejection fraction < or = 40%) but no overt heart failure.

RESULTS

Although all neurohormones except epinephrine were increased compared with values in age-matched control subjects, plasma norepinephrine (301 +/- 193 vs. 222 +/- 87 pg/ml, p < 0.001), renin activity (3.0 +/- 3.7 vs. 1.2 +/- 1.2 ng/ml per h, p < 0.001), arginine vasopressin (1.9 +/- 6.9 vs. 0.7 +/- 0.3 pg/ml, p < 0.001) and atrial natriuretic peptide (75 +/- 75 vs. 21 +/- 9 pg/ml, p < 0.001) values ranged from normal to very high, indicating a wide spectrum of neurohumoral activation. Activation of one system did not correlate with activation of another. The clinical and laboratory variables most closely associated with neurohumoral activation were Killip class, left ventricular ejection fraction, age and use of diuretic drugs. The association between neurohumoral activation and clinical and laboratory variables varied from one neurohormone to another.

CONCLUSIONS

Neurohumoral activation occurs in a significant proportion of patients at the time of hospital discharge after infarction. Which neurohormone is activated and which clinical and laboratory variables determine this activation vary from one neurohormone to another.

Prevention of myocardial infarction

Despite substantial progress in cardiovascular disease prevention, stroke and myocardial infarction remain the leading causes of death throughout the industrialized world. Treatment of high blood pressure, while contributing importantly to this progress, remains inefficient and less than optimally effective, particularly in regard to coronary artery disease events. Therapeutic intervention in the renin-angiotensin system offers promise of progress on both these fronts. Renin-sodium profiles have been shown to permit prognostic stratification of otherwise indistinguishable hypertensive patients. Indeed, low renin subjects, without other cardiovascular risk factors, have a particularly favorable prognosis. Now, the pharmacologic ability to mute the pathologic effects of angiotensin II also offers the genuine possibility that the cardioprotective value of antihypertensive therapy may be significantly improved.