Beta-adrenoceptor blockade potentiates exercise-induced release of atrial natriuretic peptide

The effects of medications on circulating levels of cardiac natriuretic peptides

Circulating cardiac natriuretic peptide levels are being used increasingly in a range of clinical circumstances. Since it is evident that drugs used in the treatment of cardiovascular disorders can modulate natriuretic peptide levels, we here review the literature documenting these effects. Diuretics, blockers of the renin-angiotensin system, vasodilator agents, dopamine-like agonists, amiodarone, and perhaps allopurinol and statins suppress natriuretic peptide levels, most obviously in heart failure. Beta-blockers stimulate natriuretic peptide concentrations in hypertensive subjects, whereas in heart failure they have little effect or are stimulatory in the short term and inhibitory with sustained therapy. Digitalis compounds and aspirin tend to increase natriuretic peptide levels, and calcium channel blocking agents have varying effects depending on the individual drug and duration of administration. The effects of other drugs are less clear. Additional information is needed regarding the effects of medications along with dissection of the role of altered cardiac secretion versus changes in plasma clearance as explanation for drug-induced perturbations in natriuretic peptide concentrations. In the meantime, clinicians need to consider the known effects of medications when interpreting plasma levels of the cardiac natriuretic peptides.

NT-proBNP in severe chronic heart failure: rationale, design and preliminary results of the COPERNICUS NT-proBNP substudy

BACKGROUND

Neither profiles nor prognostic value of cardiac N-terminal proBNP (NT-proBNP) have been prospectively evaluated in a sufficient number of patients with severe chronic heart failure (CHF) treated with carvedilol or placebo.

METHODS

Baseline and follow-up plasma concentrations of NT-proBNP were measured in the European part of the COPERNICUS Trial. This study enrolled patients with an ejection fraction <25% and symptoms of CHF at rest or on minimal exertion, equally randomized to placebo or carvedilol.

RESULTS

NT-proBNP concentrations were increased at baseline (mean+/-S.D.=579+/-822 pmol/l, median=322.5 pmol/l) with a marked decrease during follow-up in the carvedilol, but not in the placebo group. One-year mortality rates were 3.9, 12 and 27.9% in the lower, middle and upper tertiles of NT-proBNP, respectively. When mortality was calculated separately in the placebo and carvedilol group, rates were 0.8, 6.3 and 19.1% in the carvedilol treated but 6.7, 17.9 and 36.9% in the placebo treated patients.

CONCLUSIONS

NT-proBNP was a powerful predictor of subsequent all-cause mortality in patients with severe CHF. This marker should therefore be further evaluated for risk stratification and monitoring of therapy in CHF.

Relationships between the antihypertensive effects of bisoprolol and levels of plasma atrial natriuretic peptide in hypertensive patients

Previous studies have demonstrated that beta-blockade increases the levels of plasma atrial natriuretic peptide (ANP), but relationships between this effect and the antihypertensive action of beta-blockade remain unknown. In this study we investigated the amplitude and determinants of bisoprolol-induced ANP increase and the relationships between this increase and the antihypertensive effect of bisoprolol. Nineteen patients with mild to moderate hypertension were included in the study. In the first phase of the study (cross-over, placebo controlled, randomized phase), the effects of 10 mg bisoprolol on plasma ANP at rest and during exercise were compared to placebo. The antihypertensive action of bisoprolol was then evaluated after a 2-week period of treatment (10 mg/day) using ambulatory blood pressure monitoring. Bisoprolol significantly increased plasma ANP level at rest (from 30.6 +/- 20.5 to 42.8 +/- 35.6; P < 0.05) and also during exercise (from 54.7 +/- 44.3 to 119.1 +/- 159.9; pg/mL +/- SD; P < 0.05). Plasma ANP at rest was not significantly correlated with left ventricular mass. After the 15 days of treatment, the bisoprolol-induced daytime diastolic blood pressure reduction was significantly correlated to the initial bisoprolol-induced plasma ANP increase (r = 0.49, P = 0.035). These results suggest that the antihypertensive effect of beta-blocking agents could be partly mediated by an increase of ANP release.

Calcitonin gene-related peptide, neuropeptide Y and atrial natriuretic peptide distribution in guinea pig heart from paraffin wax-embedded and formalin-cryoprotected tissues

In this study, the distributions of calcitonin gene-related peptide, neuropeptide Y, and alpha-atrial natriuretic peptide 1-28 immunoreactivity, were investigated within different regions of the guinea pig heart by utilising two different methods of tissue fixation for the immunocytochemistry. The results were compared with data obtained through radioimmunoassays. We observed similar concentrations and distributions of alpha-atrial natriuretic peptide in the right atrium, with results of radioimmunoassay and immunocytochemistry, but there were no myocytes containing alpha-atrial natriuretic peptide in the left atrium or ventricles with immunocytochemistry as opposed to radioimmunoassay. The immunoreaction obtained for neuropeptide Y was more intense in the right ventricle than left. Calcitonin gene-related peptide nerve fibres were about twice as abundant in the left atrium than in the right.

Differential effects of antihypertensive drugs on neurohormonal activation: insights from a population-based sample

OBJECTIVES

The clinical course of hypertension or heart failure may be modified by the extent of concurrent neurohormonal activation. Factors that regulate neurohormones in patients with these conditions are complex. In the present study, we examined the relative contribution of antihypertensive therapy to the variability of neurohormonal levels in a well defined population based sample.

DESIGN AND SETTING

Cross-sectional study of a mixed urban and rural population.

SUBJECTS

Middle-aged individuals (n = 646) were analysed in order to elucidate determinants of neurohormone levels by uni- and multivariate comparisons. The assessment included anthropometric, echocardiographic and, if appropriate, genotype information.

RESULTS

The intake of antihypertensive drugs was related to significant alterations of neurohormone levels that, in part, exceeded the contribution of all other variables studied. Multivariate analyses revealed that renin levels were independently related to the intake of beta blockers (n = 80; -8.4 mU L-1; P = 0.001), angiotensin-converting enzyme (ACE)-inhibitors (n = 39; +15.9 mU L-1; P = 0.0001), diuretics (n = 62; +14.3 mU L-1; P = 0.0001), and calcium channel blockers (n = 45; +5.9 mU L-1; P = 0.05). Aldosterone levels were related to ACE-inhibition (-156.5 pmol L-1; P = 0.04) and diuretic treatment (+422.4 pmol L-1; P = 0.0001) in an opposite fashion whereas beta blockers and calcium channel blockers had no significant independent effects. The levels of the atrial natriuretic peptide were significantly related to the use of beta blockers (+3.9 pmol L-1; P = 0.002) and calcium channel blockers (+3.1 pmol L-1; P = 0.05). Finally, serum angiotensinogen levels and ACE activity were not found to be significantly affected by antihypertensive medication but were rather related to gender or genotype.

CONCLUSIONS

The data emphasize that antihypertensive treatment with different classes of drugs may modulate serum levels of neurohormones substantially resulting in distinct patterns of activation. These drug-related effects may require consideration when neurohormonal activation is of functional relevance or when neurohormones serve as prognostic predictors in patients with cardiovascular disorders.

Beta-adrenoceptor blockade potentiates acute exercise-induced release of atrial natriuretic peptide by increasing atrial diameter in normotensive healthy subjects

The role of atrial distension and/or adrenergic mechanisms in the regulation of atrial natriuretic peptide (ANP) secretion, plasma immunoreactive ANP, norepinephrine (NE), epinephrine (E) and left atrial diameter at rest, during and after graded bicycle exercise has been studies in 8 healthy male subjects after single doses of placebo, tertatolol 5 mg (a non-selective beta-adrenoceptor blocker), prazosin 1 mg (an alpha 1-adrenoceptor antagonist) and their combination. Systolic and diastolic left atrial diameters were measured before, during and just after exercise by bidimensional echocardiography. Exercise caused an increase in plasma ANP, which was greater after tertatolol alone, and tertatolol plus prazosin, than after placebo or prazosin alone; the mean area under the plasma ANP concentration curve was increased by 35% after tertatolol alone, by 45% after tertatolol and prazosin compared to placebo, and by 82% and 94%, respectively when compared to prazosin alone. The rise in plasma ANP was more marked during the post-exercise period: 80% after tertatolol alone, 67% after tertatolol and prazosin compared to placebo, and 133% and 115%, respectively, compared to prazosin alone. The rise in plasma ANP was accompanied by an increase in both the systolic and diastolic atrial diameter, which was also significantly greater after tertatolol alone and the combination than placebo, or after prazosin alone. beta-Adrenoceptor blockade alone did not affect the plasma catecholamine concentrations, but the exercise-induced increase in plasma norepinephrine was significantly potentiated by prazosin and by prazosin plus tertatolol, and that of plasma epinephrine by the drug combination.(ABSTRACT TRUNCATED AT 250 WORDS)

The application of nebivolol in essential hypertension: a double-blind, randomized, placebo-controlled study

This randomized, double-blind, placebo-controlled study investigated the effects of nebivolol on blood pressure, plasma renin and vasoactive hormones (aldosterone and atrial natriuretic peptide) and the heart (arrhythmias, left ventricular mass and ejection fraction) in 32 hypertensive Chinese patients aged 25-65 years. Patients received either placebo (3 men, 11 women) or nebivolol 5 mg (5 men, 13 women) once daily for 4 weeks. In the nebivolol group, a significant decrease in blood pressures (P less than 0.001) and heart rate (P less than 0.01) was seen. Nebivolol therapy also suppressed plasma renin and aldosterone concentration (P less than 0.02) but increased plasma atrial natriuretic peptide levels (P less than 0.03). No significant changes in routine blood biochemistry were demonstrated in either group. There was a tendency for left ventricular mass to decline, and left ventricular ejection fraction to rise during nebivolol therapy, but these changes did not reach statistical significance. There was no significant change in ectopic activity. None of the 32 subjects had adverse experiences requiring cessation of therapy. In conclusion, nebivolol in a dose of 5 mg daily is effective and well tolerated in patients with essential hypertension. It suppresses plasma renin and aldosterone and stimulates plasma atrial natriuretic peptide.

Blood pressure, plasma atrial natriuretic peptide and catecholamines during rapid ventricular pacing and effects of beta-adrenergic blockade in coronary artery disease

To study neurohumoral control mechanisms of the hemodynamic response to ventricular tachycardia, arterial blood pressure, plasma atrial natriuretic peptide (ANP) and catecholamine levels were monitored during simulated ventricular tachycardia before and after administration of beta blockade. Tachycardia was simulated by ventricular pacing at 150 beats/min for 150 seconds in 9 patients without and 14 with angiographically demonstrable coronary artery disease (CAD). The effects of intravenous propranolol (0.15 mg/kg) were evaluated in 7 control subjects and in 13 patients with CAD. Arterial blood pressure decreased to its minimum within 5 seconds after onset of pacing in all patients, the decrease being 27 and 30% (p = not significant) in the groups without and with CAD, respectively. Propranolol did not affect the initial decline, but blunted subsequent recovery. The ANP baseline levels were similar in both groups, increasing by 60% (p less than 0.05) and 71% (p less than 0.02) in the groups without and with CAD, respectively, during ventricular pacing. After administration of propranolol the increase in ANP was 180% in both groups. Rapid ventricular pacing did not affect catecholamine levels before propranolol, but after propranolol norepinephrine increased by 71 (p less than 0.02) and 97% (p less than 0.01) in patients without and with CAD, respectively. There was a significant correlation (r = 0.53, p = 0.001) between pacing-induced ANP and norepinephrine changes, but changes in arterial blood pressure did not correlate with those in either of these hormones. Thus, beta-adrenergic blockade blunts blood pressure recovery during simulated ventricular tachycardia. However, this is partly counterbalanced by increased circulating norepinephrine levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of enalapril on plasma atrial natriuretic peptide in late recovery phase of acute myocardial infarction

A 12 week randomised, double blind, placebo controlled study on the effect of enalapril (5-20 mg daily) on the concentration of plasma atrial natriuretic peptide level and activity of the sympathetic nervous system and renin angiotensin system was done on 27 patients who had suffered an uncomplicated acute myocardial infarction two to six months earlier. None of our patients needed drug treatment for heart failure, but their exercise capacity was markedly limited. Plasma neurohormone concentrations at baseline and after 12 weeks of treatment were also compared with those of healthy controls. Concentrations of plasma atrial natriuretic peptide concentrations remained high throughout the study in those patients on beta-blockers. Enalapril treatment had no definite effect on the concentrations of plasma atrial natriuretic peptide or other neurohormone.

Cicletanine does not affect plasma atrial natriuretic peptide concentration in healthy subjects

The effect of 50 and 150 mg cicletanine, a new vasodilator antihypertensive, on plasma atrial natriuretic peptide (ANP), cyclic GMP and antidiuretic hormone has been investigated at rest and during standardized exercise, in a double blind cross over study in healthy subjects. Exercise significantly increased in plasma ANP, cyclic GMP and antidiuretic hormone concentrations, and cicletanine did not affect any of them either at rest or during exercise. Since the alpha-1 adrenoceptor blocker prazosine decreases, beta-adrenoceptor blockers increase and the vasodilator cicletanine does not alter the plasma ANP response to exercise, it is suggested that adrenergic receptors may be directly involved in the regulation of ANP secretion.