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Altered dopaminergic responses in hypertension.
B A Clark1, R M Rosa, F H Epstein
1Department of Medicine, Beth Israel Hospital, Harvard Medical School, Boston, MA 02215.
Hypertension (Dallas, Tex. : 1979)
|June 1, 1992
Summary
Hypertensive individuals show reduced dopamine excretion and impaired response to protein meals, suggesting a renal defect in dopamine production. This may contribute to hypertension pathophysiology.
Area of Science:
- Nephrology
- Cardiovascular Physiology
- Biochemistry
Background:
- Biogenic amine metabolism, particularly dopamine, may play a role in hypertension.
- Altered dopamine metabolism could contribute to the pathophysiology of hypertension.
Purpose of the Study:
- To investigate abnormalities in dopamine excretion in hypertensive subjects.
- To examine the impact of dietary protein on dopamine metabolism in hypertension.
- To assess renal function and hemodynamic responses in normotensive versus hypertensive individuals.
Main Methods:
- Studied seven normotensive and six nonmedicated hypertensive men.
- Administered two meals: 60g protein and a noncaloric broth.
- Measured urinary excretion of dopamine and sodium.
- Assessed baseline renal plasma flow and glomerular filtration rate.
Main Results:
- Hypertensive subjects exhibited higher overall sodium excretion (56%) and tended to have lower overall dopamine excretion (p=0.06).
- Normotensive subjects showed a 23% increase in urinary dopamine after protein meal (p<0.05), which was absent in hypertensive subjects.
- Hypertensive subjects had no significant change in dopamine or sodium excretion after protein meal, unlike normotensive subjects.
Conclusions:
- Hypertensive subjects demonstrate reduced renal dopamine production relative to sodium intake and a blunted dopamine response to protein.
- Findings suggest a potential renal defect in the conversion of DOPA to dopamine in hypertensive individuals.
- These metabolic alterations may contribute to the development or maintenance of hypertension.