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Diuresis and natriuresis during continuous dopamine-1 receptor stimulation
J M Hughes1, N V Ragsdale, R A Felder
1Department of Internal Medicine, University of Virginia School of Medicine, Charlottesville 22908.
Hypertension (Dallas, Tex. : 1979)
|February 1, 1988
Summary
Long-term stimulation of renal dopamine-1 (DA1) receptors with fenoldopam increases renal plasma flow and causes sustained natriuresis. This study shows DA1 activation enhances sodium excretion without affecting blood pressure or potassium levels.
Area of Science:
- Nephrology
- Pharmacology
- Physiology
Background:
- Renal dopamine-1 (DA1) receptors play a role in regulating renal function.
- Short-term DA1 receptor stimulation increases renal plasma flow and natriuresis.
Purpose of the Study:
- To investigate the effects of long-term (24-hour) DA1 receptor stimulation on renal hemodynamic and tubular function.
- To assess the sustained natriuretic and diuretic response to fenoldopam.
Main Methods:
- A 24-hour intravenous infusion of fenoldopam, a selective DA1 receptor agonist, in 10 healthy male subjects.
- Vehicle-controlled, single-blind protocol with controlled sodium and potassium intake.
- Measurements included urine flow rate, fractional sodium excretion, renal plasma flow, and distal sodium handling.
Main Results:
- Fenoldopam infusion led to a significant increase in urine flow rate and fractional sodium excretion within 5 hours.
- Renal plasma flow increased significantly at 5 hours and remained elevated for 24 hours.
- Distal sodium load increased, and distal sodium reabsorption decreased, indicating enhanced sodium delivery to the distal tubule.
- Glomerular filtration rate, blood pressure, heart rate, aldosterone, and renin activity were unchanged.
Conclusions:
- Selective DA1 receptor activation with fenoldopam produces sustained diuresis and natriuresis.
- Long-term DA1 stimulation enhances renal plasma flow and sodium excretion without significant systemic hemodynamic effects or kaliuresis.