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The interaction of norepinephrine excretion with blood pressure and race in children
J H Pratt1, A K Manatunga, R R Bowsher
1Department of Medicine, Indiana University School of Medicine, Indianapolis.
Insights
Higher blood pressure in Black children is not linked to greater sympathetic nervous system (SNS) activity. Norepinephrine excretion was lower in Black children, suggesting potential SNS suppression or increased sensitivity.
Area of Science:
- Pediatric Health
- Cardiovascular Research
- Neuroscience
Background:
- Sympathetic nervous system (SNS) activity plays a role in blood pressure regulation.
- Racial disparities in blood pressure are well-documented in pediatric populations.
- Urinary norepinephrine is a biomarker for estimating SNS activity.
Purpose of the Study:
- To investigate the relationship between urinary norepinephrine excretion and blood pressure in children.
- To determine if race influences the relationship between SNS activity and blood pressure.
- To explore potential mechanisms behind racial differences in blood pressure.
Main Methods:
- Study included 50 Black and 49 White normotensive children aged 9-14 years.
- Blood pressure was measured, and overnight urine samples were collected.
- Urinary norepinephrine excretion was quantified using radioenzymatic assay and normalized to urinary creatinine.
Main Results:
- Black children exhibited higher age-adjusted systolic and diastolic blood pressure compared to White children.
- Nocturnal urinary norepinephrine excretion correlated positively with diastolic blood pressure in both racial groups.
- Norepinephrine excretion rates were significantly lower in Black children than in White children.
Conclusions:
- Elevated blood pressure in Black children is unlikely due to increased SNS activity.
- Lower norepinephrine excretion in Black children may indicate suppressed SNS activity, possibly due to plasma volume expansion.
- Alternatively, Black children might exhibit heightened sensitivity to SNS influences.
Objective:
The purpose of this study was to examine the relationship between urinary norepinephrine excretion and blood pressure, and to determine the influence of race on this relationship. Urinary norepinephrine was used to estimate renal and systemic sympathetic nervous system (SNS) activity.
Design:
Fifty black and forty-nine white normotensive children aged 9-14 years had their blood pressure measured, and provided an overnight urine sample.
Methods:
Urinary norepinephrine was measured by radioenzymatic assay. Excretion rates of norepinephrine were expressed per milligram urinary creatinine.
Results:
Black children had age-adjusted mean diastolic and systolic blood pressure which was higher than in white children. For both blacks and whites, nocturnal urinary norepinephrine excretion rates were positively related to age-adjusted mean diastolic blood pressure, but not to systolic blood pressure. Norepinephrine excretion was significantly lower in black children compared with white children.
Conclusion:
These findings suggest that the higher blood pressures in black children were not causally related to greater SNS activity. The SNS may have been suppressed in black children, possibly by a greater expansion of plasma volume, alternatively, black children may have been more sensitive to the influences of the SNS than white children.