Blood pressure and atrial natriuretic peptides correlate throughout the day

Diurnal Variations in Natriuretic Peptide Levels: Clinical Implications for the Diagnosis of Acute Heart Failure

BACKGROUND

Current guidelines recommend interpreting concentrations of NPs (natriuretic peptides) irrespective of the time of presentation to the emergency department. We hypothesized that diurnal variations in NP concentration may affect their diagnostic accuracy for acute heart failure.

METHODS

In a secondary analysis of a multicenter diagnostic study enrolling patients presenting with acute dyspnea to the emergency department and using central adjudication of the final diagnosis by 2 independent cardiologists, the diagnostic accuracy for acute heart failure of BNP (B-type NP), NT-proBNP (N-terminal pro-B-type NP), and MR-proANP (midregional pro-atrial NP) was compared among 1577 daytime presenters versus 908 evening/nighttime presenters. In a validation study, the presence of a diurnal rhythm in BNP and NT-proBNP concentrations was examined by hourly measurements in 44 stable individuals.

RESULTS

Among patients adjudicated to have acute heart failure, BNP, NT-proBNP, and MR-proANP concentrations were comparable among daytime versus evening/nighttime presenters (all P=nonsignificant). Contrastingly, among patients adjudicated to have other causes of dyspnea, evening/nighttime presenters had lower BNP (median, 44 [18-110] versus 74 [27-168] ng/L; P<0.01) and NT-proBNP (median, 212 [72-581] versus 297 [102-902] ng/L; P<0.01) concentrations versus daytime presenters. This resulted in higher diagnostic accuracy as quantified by the area under the curve of BNP and NT-proBNP among evening/nighttime presenters (0.97 [95% CI, 0.95-0.98] and 0.95 [95% CI, 0.93-0.96] versus 0.94 [95% CI, 0.92-0.95] and 0.91 [95% CI, 0.90-0.93]) among daytime presenters (both P<0.01). These differences were not observed for MR-proANP. Diurnal variation of BNP and NT-proBNP with lower evening/nighttime concentration was confirmed in 44 stable individuals (P<0.01).

CONCLUSIONS

BNP and NT-proBNP, but not MR-proANP, exhibit a diurnal rhythm that results in even higher diagnostic accuracy among evening/nighttime presenters versus daytime presenters.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifiers: NCT01831115, NCT02091427, and NCT02210897.

Ethnic, geographic and dietary influences upon vasoactive hormones and blood pressure among Greenland Inuit and Danes

AIM

To study levels of vasoactive hormones and urinary excretion of sodium and potassium between groups of Greenland Inuit and Danes, and to analyse the relationship between these hormones and 24-h blood pressure, including nightly blood pressure dips and pulse pressure.

METHODS

145 Greenlandic participants were categorized in three groups according to degree of westernization, based on dietary habits and current place of residence; 41 Danes were included as controls. Twenty-four-hour blood pressure was measured. Venous plasma concentrations of vasoactive hormones were measured. Urine was collected for 24 hours for analysis of excretion of sodium and potassium.

RESULTS

The Inuit population of Greenland had a lower diastolic blood pressure, a higher pulse pressure and lower nocturnal blood pressure dip than Danes had. Angiotensin II in plasma and urine excretion of potassium were higher among Greenlanders compared with Danes, irrespective of diet and place of residence. Aldosterone and urine excretion of sodium were significantly higher among participants in Denmark compared with participants in Greenland. Brain natriuretic peptide and atrial natriuretic peptide were independently and negatively associated with diastolic blood pressure, and vasopressin was positively associated with systolic blood pressure and pulse pressure. Ethnic differences in the effect of vasoactive hormones or urinary sodium and potassium excretion could not explain the difference in blood pressure.

CONCLUSION

It is suggested that a high dietary intake of potassium and low sodium intake among Greenlanders may affect blood pressure. Further attention should be drawn to the occurrence of high pulse pressure and high activity in the renin-angiotensin system in Inuit populations.

Altered Circadian Relationship Between Serum Nitric Oxide, Carbon Dioxide, and Uric Acid in Multiple Sclerosis

The free radical nitric oxide (NO*) is involved in a variety of diverse biological processes from acting as a vasodilator in the cardiovascular system to being the rate-limiting component in the production of peroxynitrite (ONOO-), a contributor to neurodegenerative disorders such as multiple sclerosis (MS). Uric acid (UA), the end product of purine metabolism in humans and a selective inhibitor of toxic reactions attributed to radicals formed by the interaction of ONOO- and CO2, is generally low in MS patients. We investigated the relationship between serum ONOO-, CO2, and UA in MS patients and normal controls by comparing the circadian characteristics of the NO* metabolites nitrite/ nitrate (NO), CO2, and UA. In this preliminary study, we found the functional relationship ascribed to the circadian timing of the peak and trough levels of NO, CO2, and UA in healthy subjects to be clearly altered in MS patients. These findings suggest that alterations in the temporal relationship between the 24h pattern in serum ONOO- formation and UA may either contribute to or reflect the disease processes in MS.

Circadian patterns in the onset of cardiogenic acute pulmonary edema

BACKGROUND

Circadian patterns of onset favoring the morning hours have been demonstrated for many cardiovascular disorders. Although much is known about cardiogenic acute pulmonary edema (CAPE), the relationship between time of day and CAPE episode onset has not been previously studied.

METHODS

We examined 154 consecutive episodes of CAPE treated at an urban community hospital to determine whether circadian patterns existed in the time these episodes began.

RESULTS

For all episodes, a significant circadian pattern existed, with peak onset between 6:00 and 11:59 A.M. (p < 0.01). When CAPE episodes were analyzed by the most probable precipitant of pulmonary edema, only the pattern for patients with progressive symptoms, showing a peak in the 6:00 and 11:59 A.M. interval, was statistically significant (p < 0.01). Although a similar trend existed for CAPE occurring in association with acute myocardial infarction, the pattern fell short of statistical significance (p = 0.09).

CONCLUSIONS

These data suggest that circadian patterns favoring the morning hours exist for episodes of CAPE, and that patterns may vary depending on the precipitant of the episode.

In vitro circadian ANP secretion by gene transferring cells encapsulated in polycaprolactone tubes: gene chronotherapy

A new insofar as chronobiologic therapeutic approach by atrial natriuretic peptide (ANP) for hypertension and/or congestive heart failure (CHF) is based on the release of ANP from ANP cDNA transfected Chinese Hamster Ovary (CHO) cells encapsulated in polycaprolactone (PCL) tubes. ANP secretion was maintained for at least 6 months. The encapsulated cells remained viable during culturing. Control cells without transferred ANP cDNA were negative. ANP secretion is circadian periodic, peaking around 04:18, shifted to around 07:56 by melatonin treatment. The encapsulation technique, based on principles of chronotherapy, may provide a more efficient gene therapy, applicable for eventual human implantation of gene transferred cells.