Hypertension in minorities: blacks

Effect of Digoxin Use Among Medicaid Enrollees With Atrial Fibrillation

BACKGROUND

Recently published analysis of contemporary atrial fibrillation (AF) cohorts showed an association between digoxin and increased mortality and hospitalizations; however, other studies have demonstrated conflicting results. Many AF cohort studies did not or were unable to examine racial differences. Our goal was to examine risk factors for hospitalizations and mortality with digoxin use in a diverse real-world AF patient population and evaluate racial differences.

METHODS AND RESULTS

We performed a retrospective cohort analysis of claims data for Medicaid beneficiaries, aged 18 to 64 years, with incident diagnosis of AF in 2008 with follow-up until December 31, 2009. We created Kaplan-Meier curves and constructed multivariable Cox proportional hazard models for mortality and hospitalization. We identified 11 297 patients with an incident diagnosis of AF in 2008, of those, 1401 (12.4%) were on digoxin. Kaplan-Meier analysis demonstrated an increased risk of hospitalization with digoxin use overall and within race and heart failure groups. In adjusted models, digoxin was associated with an increased risk of hospitalization (adjusted hazard ratio, 1.54; 95% confidence interval, 1.39-1.70) and mortality (adjusted hazard ratio, 1.50; 95% confidence interval, 1.05-2.13). Overall, blacks had a higher risk of hospitalization but similar mortality when compared with whites regardless of digoxin use. We found no significant interaction between race and digoxin use for mortality (P=0.4437) and hospitalization (P=0.7122).

CONCLUSIONS

Our study demonstrates an overall increased risk of hospitalizations and mortality with digoxin use but no racial/ethnic differences in outcomes were observed. Further studies including minority populations are needed to critically evaluate these associations.

The 2010 Canadian Cardiovascular Society guidelines for the diagnosis and management of heart failure update: Heart failure in ethnic minority populations, heart failure and pregnancy, disease management, and quality improvement/assurance programs

Since 2006, the Canadian Cardiovascular Society heart failure (HF) guidelines have published annual focused updates for cardiovascular care providers. The 2010 Canadian Cardiovascular Society HF guidelines update focuses on an increasing issue in the western world - HF in ethnic minorities - and in an uncommon but important setting - the pregnant patient. Additionally, due to increasing attention recently given to the assessment of how care is delivered and measured, two critically important topics - disease management programs in HF and quality assurance - have been included. Both of these topics were written from a clinical perspective. It is hoped that the present update will become a useful tool for health care providers and planners in the ongoing evolution of care for HF patients in Canada.

Combination treatment with telmisartan and hydrochlorothiazide in black patients with mild to moderate hypertension

BACKGROUND

Hydrochlorothiazide (HCTZ) is commonly used to treat black patients with hypertension. To avoid the metabolic disturbances associated with high-dose HCTZ, blood pressure control may be achieved by combining low doses with another antihypertensive.

HYPOTHESIS

The study was undertaken to assess the tolerability and antihypertensive dose-response efficacy of telmisartan and HCTZ and their combination in black patients with mild to moderate hypertension (mean supine blood pressure 140/95-200/114 mmHg).

METHODS

Following a 4-week, single-blind, placebo run-in period, 222 black patients were randomized to once-daily treatment with one of 20 different double-blind combinations of telmisartan (0, 20, 40, 80, 160 mg) and HCTZ (0, 6.25, 12.5, 25 mg) for 8 weeks. Blood pressure was measured at baseline and after 2, 4, and 8 weeks.

RESULTS

Telmisartan 80 mg/HCTZ 12.5 mg reduced supine trough diastolic blood pressure (DBP)--primary efficacy parameter--by 13.3 mmHg, and supine trough systolic blood pressure (SBP) by 21.5 mmHg. These reductions represented benefits of 13.7/8.7 mmHg over telmisartan 80 mg and 12.3/8.1 mmHg over HCTZ 12.5 mg (p < 0.01). Telmisartan 40 mg/HCTZ 12.5 mg reduced supine trough SBP/DBP by 14.3/10.0 mmHg, amounting to 12.3/3.3 mmHg more than telmisartan 40 mg and 5.1/4.8 mmHg more than HCTZ 12.5 mg. This reached significance for the comparisons with telmisartan 40 mg for SBP and HCTZ 12.5 mg for DBP (p<0.05). A response surface analysis and therapeutic response rates confirmed the additive antihypertensive effects of telmisartan and HCTZ. All treatments were well tolerated, with side-effect profiles comparable with placebo. Adverse events were mainly transient and of mild to moderate severity.

CONCLUSIONS

Telmisartan 80 mg combined with HCTZ 12.5 mg is effective and well tolerated in black patients with mild to moderate hypertension, providing greater antihypertensive activity than the corresponding monotherapies.

Hitting the target: why existing measures of "religiousness" are really reverse-scored measures of "secularism"

Over 100 measures of religiousness and spirituality are used in research investigating the associations between religion and health. These measures are often used to assess "religiousness in general," but this approach lumps together widely divergent worldviews in ways that can distort religion beyond recognition. The authors suggest that the existing measures of religiousness are perhaps better understood as reverse-coded measures of "secularism." This argument suggests that the existing data regarding religiousness and health might be best interpreted as demonstrating a small, robust health liability associated with a deliberately secular worldview. If true, this conclusion might change the direction of future research, and it would imply that meaningful inferences about the health associations of religious practice will depend on developing tools that measure specific religions in their particularity.

Understanding social disparities in hypertension prevalence, awareness, treatment, and control: the role of neighborhood context

The spatial segregation of the US population by socioeconomic position and especially race/ethnicity suggests that the social contexts or "neighborhoods" in which people live may substantially contribute to social disparities in hypertension. The Chicago Community Adult Health Study did face-to-face interviews, including direct measurement of blood pressure, with a representative probability sample of adults in Chicago. These data were used to estimate socioeconomic and racial-ethnic disparities in the prevalence, awareness, treatment, and control of hypertension, and to analyze how these disparities are related to the areas in which people live. Hypertension was significantly negatively associated with neighborhood affluence/gentrification, and adjustments for context eliminated the highly significant disparity between blacks/African-Americans and whites, and reduced the significant educational disparity by 10-15% to borderline statistical significance. Awareness of hypertension was significantly higher in more disadvantaged neighborhoods and in places with higher concentrations of blacks (and lower concentrations of Hispanics and immigrants). Adjustment for context completely eliminated blacks' greater awareness, but slightly accentuated the lesser awareness of Hispanics and the greater levels of awareness among the less educated. There was no consistent evidence of either social disparities in or contextual associations with treatment of hypertension, given awareness. Among those on medication, blacks were only 40-50% as likely as whites to have their hypertension controlled, but context played little or no role in either the level of or disparities in control of hypertension. In sum, residential contexts potentially play a large role in accounting for racial/ethnic and, to a lesser degree, socioeconomic disparities in hypertension prevalence and, in a different way, awareness, but not in treatment or control of diagnosed hypertension.

Heart Failure Management in African Americans: Meeting the Challenge

Heart failure affects 3% of African Americans. The etiology of disease and prognosis for these patients differs substantially from those for non-African Americans. A history of hypertension is associated with development of heart failure more often in African Americans than in non-African Americans and it also appears that target organ involvement is more severe in African Americans with hypertension than in other patient subgroups. Reviewing the results from large-scale clinical end point studies suggests that optimal treatment for heart failure in African Americans may differ from that of their non-African American counterparts. More importantly, concomitant use of beta blockers and angiotensin-converting enzyme inhibitors may be as effective in African Americans as in non-African Americans. Utilizing angiotensin-converting enzyme inhibitors alone may not represent ideal therapy. Of the drugs studied, especially among the beta blockers, carvedilol may be the most effective to use for this population.

Pharmacologic Agents in the Management of Hypertension-Nisoldipine Coat-Core

Nisoldipine coat-core (CC), a 1,4-dihydropyridine calcium antagonist, is indicated for the treatment of hypertension and may be used alone or in combination with other antihypertensive agents. The CC technology allows for extended delivery of the drug and once-daily dosing. Nisoldipine CC tablets are absorbed across the entire gastrointestinal tract, including the colon. Eighty percent of the total dose is in the slow-release outer coat, while the core has immediate-release characteristics suitable for absorption in the distal gastrointestinal tract. Numerous double-blind, randomized studies of this agent have been done in patients with hypertension. The use of nisoldipine CC reduced both clinic and ambulatory blood pressure to a similar degree when compared with angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, and the calcium antagonists amlodipine and felodipine. The drug has also been studied in hypertensive African Americans and demonstrated equivalent efficacy to amlodipine. Tolerability of the drug is good, with the most common side effect of edema at a rate similar to other dihydropyridine calcium antagonists. Thus, results of more than a decade of clinical trial data support the use of nisoldipine CC as once-daily therapy for the treatment of hypertension.

Heart failure in African Americans

The demographics of the United States are changing, and in the next few decades there will no longer be a racial/ethnic majority population. Increased awareness of cardiovascular disease (CVD) in special populations is warranted as these populations increase. Heart failure carries a substantial burden on those affected, particularly African Americans, who have a disproportionate burden of heart disease. Current treatments for heart failure include angiotensin-converting enzyme inhibitors, beta-blockers, angiotensin II-receptor antagonists, and vasodilating agents. This review discusses the unique characteristics of CVD in African Americans and addresses the need for targeted treatments to reduce the excess burden found in this population.

Treatment of the african-american patient with congestive heart failure

African Americans have a higher burden of cardiovascular disease than white Americans, including a higher prevalence of heart failure. In addition, heart failure in African Americans conforms to a more malignant natural history. Hypertension is most often cited as the sole etiology of heart failure in African Americans. Most of the major trials of pharmacotherapy for the management of chronic heart failure have failed to include significant numbers of African-American patients. Based on the available evidence, there is no reason to withhold standard evidence-based medical therapy for heart failure. Even though there is much controversy as to the efficacy of angiotensin-converting enzyme (ACE) inhibitors and beta blockers in African Americans, in the absence of definitive data they should be used. Recently, the combination of isosorbide dinitrate and hydralazine has been demonstrated to improve survival in African Americans with New York Heart Association class III and IV heart failure, and represents an adjunctive treatment option when added to standard medical therapy consisting of ACE inhibitors, beta blockers, digoxin, diuretics, and aldosterone antagonists. Emerging evidence suggests that this therapy may be targeting a novel mechanism of heart failure progression (ie, nitric oxide bioavailability) found in African Americans.

Comparison of outcomes of white versus black patients hospitalized with heart failure and preserved ejection fraction

Black patients who have heart failure (HF) may have a larger proportion of HF with preserved ejection fraction (PEF) than white patients because of the greater prevalence and severity of hypertension and left ventricular hypertrophy in blacks. However, studies have not systematically evaluated differences by race in patients who have HF-PEF compared with those who have systolic HF (SHF). Therefore, we examined baseline characteristics and long-term outcomes in patients who had HF-PEF compared with those who had SHF, with an emphasis on variation by race, in a biracial cohort of patients treated within the Veterans Health Administration health care system. In a cohort of 448 patients (192 blacks and 256 whites) hospitalized with HF, 27% had HF-PEF. The proportion of HF-PEF was similar in black (25%) and white (29%) patients (p = 0.4). Among patients who had SHF, black patients were younger, had lower prevalences of atrial fibrillation and diabetes, and had less co-morbidities than white patients, whereas there were no significant differences in these variables by race in patients who had HF-PEF. However, among patients who had SHF or HF-PEF, blacks had a lower prevalence of coronary disease, higher systolic and diastolic blood pressures, and higher serum levels of creatinine than white patients. In addition, mortality and readmission rates for HF did not differ by race among patients who had HF-PEF. Overall, patients who had HF-PEF had a high morbidity rate (30% patients were readmitted for HF in </=6 months) and a high mortality rate (44% at 3 years), despite the use of angiotensin-converting enzyme inhibitors by 66% of patients at discharge. This underscores the importance of evaluating other agents for the treatment of patients who have HF-PEF.

The prevention of heart failure in minority communities and discrepancies in health care delivery systems

This article discusses risk factors for cardiovascular disease in the minority community, including hypertension, obesity, diabetes,and diet. The minority community exhibits important population differences regarding risk and outcomes for cardiovascular disease. The complete explanation for these differential outcomes is lacking and likely to be multifactorial in origin; however, disparities in health care (differences in the quality of health care that are not due to access-related factors or clinical needs, to preferences, or to the appropriateness of the intervention) may emanate from decisions made by the patient, provider, or health care system. Hypertension as a disease entity is strikingly pathologic in African Americans. Correspondingly, the incidence of cardiovascular mortality due to hypertensive heart disease is fourfold higher in African Americans than in non-Hispanic whites. Hypertension and heart failure can be treated effectively in the minority community with a regimen of agents not dissimilar from that used for the general population. Treatment regimens should be individualized based on the disease presentation, associated comorbidity, and disease severity and not on something as arbitrary as race.

An assessment of racial differences in clinical practices for hypertension at primary care sites for medically underserved patients

Ethnic disparities in hypertension-related outcomes may relate to differences in medical care. This study assessed primary care sites serving low-income patients to determine if differences in process and treatment indicators might contribute to disparities in outcomes. Eight sites were enrolled with 100,000 patients, collectively. Trained nurses abstracted a random sample of medical records for diagnoses, laboratory data, medications, and demographic variables. Data were obtained on 1250 white and 2786 African-American adults. African Americans were more likely (p<0.01) to be hypertensive (44% vs. 23%) and diabetic (16% vs. 8%) than whites. African Americans were more likely to have serum creatinine, potassium, lipid, and glycosylated hemoglobin values recorded in the medical record than whites (p<0.01). African-American hypertensives were more likely (p<0.05) than white hypertensives to receive calcium channel blockers, angiotensin-converting enzyme inhibitors, diuretics, and combination therapy. Thus, there appeared to be little difference in the level of care between the two groups. Based on the sites examined, ethnic variations in important process and treatment indicators do not explain racial differences in cardiovascular and renal outcomes.

The natural history, epidemiology, and prognosis of heart failure in African Americans

Heart failure is more common in African Americans and appears to be of worse severity. At the time of diagnosis, left ventricular function is more severely impaired and the clinical class is more advanced. The strongest risk factor for heart failure in African Americans appears to be hypertension, which is both more prevalent and more pathologic in African Americans. It is likely that heart failure represents an important end organ effect of hypertension. When affected by heart failure, African Americans experience a greater rate of hospitalization and may be exposed to a higher mortality risk as well. Genomic medicine has yielded a number of candidate single nucleotide polymorphisms that might contribute to the excess pathogenicity of heart failure in African Americans, but much more work needs to be done in larger cohorts. Effective therapy of heart failure must start with the recognition of the different manifestations of heart failure in African Americans. An increased awareness of the risk of hypertension followed by early and effective intervention may reduce the risk of heart failure in this population.

Alpha2-adrenergic receptor-induced vascular constriction in blacks and whites

Black Americans have a reduced hypotensive response to the alpha2-adrenergic receptor agonist clonidine compared with whites, despite similar central sympathoinhibition. This reduced hypotensive response might be explained by greater postsynaptic vascular alpha2-adrenergic receptor vasoconstrictive response. However, clonidine has a low alpha2/alpha1 selectivity ratio. Therefore, to determine the role of altered alpha2-adrenergic receptor vascular sensitivity in ethnic differences in vascular response, we compared local vascular responses with the highly selective alpha2-adrenergic receptor agonist dexmedetomidine in healthy black (n=18) and white (n=19) subjects. Increasing doses of dexmedetomidine (0.001 to 1000 ng/min) were infused into a dorsal hand vein, and the local response was measured with a linear variable differential transformer. Dexmedetomidine caused pronounced venoconstriction, with an average (+/-SD) maximum response of 74.5+/-17.72% but with no difference between blacks and whites. There was substantial intersubject variability in the sensitivity to dexmedetomidine; the dose resulting in 50% (ED50) of maximum vasoconstriction ranged from 0.08 ng/min to 256 ng/min. The geometric mean ED50 was 2.28 ng/min (95% CI, 0.02 to 271.6 ng/min) in blacks and 1.58 ng/min (95% CI, 0.11 to 24.55 ng/min) in whites (P=0.59). Our data indicate that alpha2-adrenergic receptor-induced venoconstriction is similar in blacks and whites. These findings do not support the hypothesis that altered alpha2-adrenergic receptor sensitivity is the explanation for the decreased blood pressure response to systemic administration of clonidine in blacks. The response to dexmedetomidine provides a model that will allow further study of the regulation of alpha2-adrenergic receptor-mediated vascular responses

Survival rates are similar between African American and white patients with heart failure

BACKGROUND

The clinical characteristics of heart failure differ significantly between African American patients and white patients, apparently as a result of differences in the pathobiology of the condition in the races. We investigated the hypothesis that race also influences the survival of patients with heart failure.

METHODS

Data from the University of North Carolina Heart Failure Database were analyzed for 853 patients (44% African American, 32% women) who had symptomatic heart failure (New York Heart Association class 2.8 +/- 0.02 [mean +/- SEM]) with a reduced left ventricular ejection fraction of 26% +/- 0.5% and a body mass index of 27 +/- 0.2. Data on vital status were available in 96.4% of these patients, with a mean length of follow-up of 3.8 +/- 0.1 years.

RESULTS

An unadjusted univariate proportional-hazards analysis suggested similar survival rates between African American patients and white patients in the study population (relative risk, 0.90; 95% CI, 0.73-1.10; P =.293). Adjusted analysis, taking into account the characteristics shown to be of prognostic importance, demonstrated no difference in survival rate between African American patients and white patients (relative risk,1.12; 95% CI, 0.89-1.42; P =.336). The adjusted relative risk of all-cause mortality in the respective races among patients with heart failure caused by ischemic heart disease was 1.21 (95% CI, 0.80-1.84; P =.367).

CONCLUSION

African American and white patients with symptomatic heart failure had similar survival rates in our database.

High prevalence of target organ damage in young, African American inner-city men with hypertension

Young, urban, African American men are at particularly high risk of hypertension and its cardiovascular complications. Left ventricular hypertrophy and renal dysfunction are manifestations of target organ damage from hypertension that predict adverse cardiovascular events. The subjects of this study were 309 African American men, age 18-54 years, with hypertension, residing in inner-city Baltimore. Echocardiograms, electrocardiograms, serum creatinine, and the urinary albumin-creatinine ratio were obtained to evaluate hypertensive target organ damage. Fifty-three percent of the men reported use of antihypertensive medications, of whom 80% were on monotherapy. Calcium channel blockers were used most frequently. The mean echocardiographic left ventricular mass was 211+/-68 g, with a prevalence of echocardiographic left ventricular hypertrophy of 30%. There were 14 men (5%) with extremely high left ventricular mass, >350 grams. Left ventricular systolic dysfunction was seen in 9% of the men with uncontrolled hypertension, and none of the men with controlled hypertension (p=0.02). Renal dysfunction was found in 12% of the subjects, and microalbuminuria or gross proteinuria in 34%. The authors conclude that there is a high prevalence of cardiac and renal abnormalities in inner-city African American men with hypertension, especially in men on antihypertensive therapy with uncontrolled hypertension. It is imperative that cost-effective medications and culturally acceptable health care delivery programs be developed, tested, and integrated into health systems, with strategies specifically relevant to this high-risk population, to decrease the largely preventable morbidity and mortality associated with hypertension.

Church rosters: is this a viable mechanism for effectively recruiting African Americans for a community-based survey?

OBJECTIVES

The purpose of this report is to describe the process, results, and implications in the phone recruitment of African Americans through church rosters for a survey of diet-and blood pressure-related awareness and hypertension prevalence.

DESIGN

The survey was conducted using a non-probability sample of churches and a random selection of participants from church rosters. Recruitment strategies included frequent contact with pastors and church representatives, presentations, standard and tailored recruitment approaches, and bi-annual progress reports. Church representatives provided the rosters and assisted in arranging interviews, which were conducted at church or the participants' homes.

RESULTS

Of 742 randomly selected, 315 (42.4%) were ineligible because of an unavailable or unreachable number, a move, discontinued church membership, death, or other reasons. Of the 344 eligible, 45.8% participated, 30.2% refused, 4.4% agreed to participate but did not, and 19.6% were incompletes (called less than three times before recruitment was terminated). Among participants, 70.4% were female, 58.2% had completed college, and the age range was 19-91 years. The survey's sample size goal of 196 was met.

CONCLUSIONS

In this study population, over 45% who were eligible participated. Rapport established with church representatives and congregations was critical to the sampling process. Using church rosters can be a low-cost, effective recruitment tool. However, key factors to consider when recruiting African Americans in this manner include: trust, study eligibility criteria, roster accuracy, and time, and generalizability.

Race and the response to adrenergic blockade with carvedilol in patients with chronic heart failure

BACKGROUND

The benefits of angiotensin-converting-enzyme inhibitors and beta-blockers may be smaller in black patients than in patients of other races, but it is unknown whether race influences the response to carvedilol in patients with chronic heart failure.

METHODS

In the U.S. Carvedilol Heart Failure Trials Program, 217 black and 877 nonblack patients (in New York Heart Association class II, III, or IV and with a left ventricular ejection fraction of no more than 0.35) were randomly assigned to receive placebo or carvedilol (at doses of 6.25 to 50 mg twice daily) for up to 15 months. The effects of carvedilol on ejection fraction, clinical status, and major clinical events were retrospectively compared between black and nonblack patients.

RESULTS

As compared with placebo, carvedilol lowered the risk of death from any cause or hospitalization for any reason by 48 percent in black patients and by 30 percent in nonblack patients. Carvedilol reduced the risk of worsening heart failure (heart failure leading to death, hospitalization, or a sustained increase in medication) by 54 percent in black patients and by 51 percent in nonblack patients. The ratios of the relative risks associated with carvedilol for these two outcome variables in black as compared with nonblack patients were 0.74 (95 percent confidence interval, 0.42 to 1.34) and 0.94 (95 percent confidence interval, 0.43 to 2.05), respectively. Carvedilol also improved functional class, ejection fraction, and the patients' and physicians' global assessments in both the black patients and the nonblack patients. For all these measures of outcome and clinical status, carvedilol was superior to placebo within each racial cohort (P<0.05 in all analyses), and there was no significant interaction between race and treatment (P> 0.05 in all analyses).

CONCLUSIONS

The benefit of carvedilol was apparent and of similar magnitude in both black and nonblack patients with heart failure.

Psychologic factors as precursors to hypertension

The possibility that certain psychologic factors lead to hypertension has been considered by many investigators over the past 60 years, but prospective studies with suitable methods to evaluate this hypothesis were not available for analysis until the 1990s. There are now five large longitudinal studies demonstrating a relation between symptoms of anxiety or depression and subsequent hypertension incidence. Anger expression, long considered a major psychologic factor in hypertension, has been studied less extensively, and the findings to date are less consistent. While some evidence supports the biological plausibility of psychologic factors as risk factors for hypertension, biobehavioral mechanisms explaining the relationship have not been adequately explored. The results of these recent studies may lead to new intervention trials specifically selecting hypertensive patients with anxiety or depression for treatment with stress reduction or other appropriate psychologic therapies. Such studies would further contribute to the evaluation of anxiety and depression as risk factors for hypertension.

Plasma hydrogen peroxide production in human essential hypertension: role of heredity, gender, and ethnicity

Oxygen free radicals, including hydrogen peroxide, may mediate oxidative stress in target organ tissues and contribute to cardiovascular complications in hypertension. To examine heritability of hydrogen peroxide production, we investigated this trait in a family-based cohort consisting of family members (n=236) ascertained through probands (n=57) with essential hypertension. Significant effects on hydrogen peroxide production were found for gender and ethnicity, with men having greater values than women (P<0.001) and white subjects having greater values than black subjects (P=0.025). Hydrogen peroxide production correlated directly with plasma renin activity (P=0.015), suggesting an important interaction between circulating oxygen radicals and the renin-angiotensin system and a potential mechanism for lower hydrogen peroxide values observed in blacks. Heritability estimates from familial correlations revealed that approximately 20% to 35% of the observed variance in hydrogen peroxide production could be attributed to genetic factors, suggesting a substantial heritable component to the overall determination of this trait. Hydrogen peroxide production negatively correlated with cardiac contractility (r=-0.214, P=0.001) and renal function (r=-0.194, P=0.003). In conclusion, these results indicate that hydrogen peroxide production is heritable and is related to target organ function in essential hypertension. Genetic loci influencing hydrogen peroxide production may represent logical candidates to investigate as susceptibility genes for cardiovascular target organ injury.

Acute hypotensive, natriuretic, and hormonal effects of nifedipine in salt-sensitive and salt-resistant black normotensive and hypertensive subjects

In a randomized double-blind study, we compared the short-term effects of nifedipine (10 mg 3x daily for 1 day) versus placebo on 24-h blood pressure, diuresis, natriuresis, urinary excretion of dopamine and metabolites, and on plasma renin activity (PRA) and plasma aldosterone levels in 18 black hypertensive (HT) patients [eight salt-resistant (HT-SR) and 10 salt-sensitive (HT-SS)], and in 20 black normotensive (NT) subjects (12 NT-SR and eight NT-SS) who were studied randomly with both a high- (HS) and a low-salt (LS) diet. In comparison to placebo, nifedipine significantly decreased 24-h mean BP in all groups either with HS or LS diets (all p<0.05). With HS, greater hypotensive effects were achieved in NT-SS (-10+/-2 mm Hg) versus NT-SR (-3+/-1 mm Hg; p<0.05) and in HT-SS (-18+/-2 mm Hg) versus HT-SR (-12+/-2 mm Hg; p<0.05). In NT-SS and HT-SS, nifedipine induced greater (p<0.05) BP decrease with HS (-10+/-2 and -18+/-2 mm Hg) than with LS (-4+/-1 and -9+/-1 mm Hg, respectively), whereas in NT-SR and HT-SR, the hypotensive effect did not differ between HS and LS. Nifedipine versus placebo significantly increased natriuresis and fractional excretion of sodium in all groups only with HS (p<0.05) but not with LS diets. Only in HT-SS were the hypotensive and natriuretic effects of nifedipine significantly correlated (r = -0.77; p<0.01). Nifedipine produced a similar increase of the urinary excretion of dopamine, L-DOPA, and of DOPAC in all subjects, which did not correlate with hypotensive and natriuretic effects. Nifedipine did not modify plasma levels of renin and of aldosterone except in NT-SS with HS, in whom nifedipine increased PRA levels (p <0.05). We conclude that although nifedipine reduces BP in all groups of NT and HT with LS and HS diets, the effect is greater in salt-sensitive subjects with HS. Although in HT-SS with HS, the short-term natriuretic response to nifedipine may contribute to its hypotensive effects, the diuretic-natriuretic effect of nifedipine is not necessary for the expression of its hypotensive effect. Moreover, it is unlikely that any short-term effects of nifedipine either on the renal dopaminergic system or on the secretion of aldosterone explain nifedipine short-term hypotensive and diuretic-natriuretic effects.

Contribution of nitric oxide to the beneficial effects of enalapril in the fructose-induced hyperinsulinemic rat

We examined accumulating evidence of the positive contribution of nitric oxide to the pharmacological effects of converting enzyme inhibitors in 36 rats rendered hypertensive, hyperinsulinemic, and hypertriglyceridemic by a fructose-enriched diet. We studied the response of blood pressure, insulin, and triglyceride levels to inhibition of either converting enzyme-kininase II, nitric oxide synthase, or both. Two weeks of the converting enzyme inhibitor enalapril (20 mg/kg) reduced blood pressure from 137 +/- 2 to 105 +/- 7 mm Hg, insulin from 7.6 +/- 2.0 to 2.2 +/- 1.1 pg/mL, and triglycerides from 292 +/- 37 to 163 +/- 37 mg/dL. Treatment with NG-nitro-L-arginine methyl ester (100 mg/kg) raised blood pressure from 144 +/- 7 to 170 +/- 8 mm Hg without affecting the other parameters. Two weeks of concomitant treatment with both agents blunted the hypotensive and beneficial metabolic effects of enalapril; thus, final blood pressure (141 +/- 7 mm Hg), insulin (6.4 +/- 2.4 pg/mL), and triglyceride (231 +/- 51 mg/dL) values were no different from those of untreated fructose-fed rats. These data suggest that persistent synthesis of nitric oxide contributes to the vasodilator and metabolic effects of enalapril in the fructose-fed rat model.