Intervention Study to Compare the Natriuretic Effects of Enalapril on Low and High Salt Diet

Study Overview
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Brief Summary
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The kidney plays a crucial role in maintaining salt balance by two opposing physiological mechanisms: the renal dopaminergic system which enhances salt excretion and the renin-angiotensin system (RAS) which causes salt retention. Salt-sensitive hypertension occurs when this balance is altered or abnormal. We hypothesized that this balance is influenced by salt intake: therefore dietary salt affects the natriuretic response to the renal dopaminergic agonist Fenoldopam, and the Angiotensin Converting Enzyme inhibitor, Enalapril. In this trial we study normal salt balance mechanisms in salt resistant adults with normal blood pressure.

Detailed Description
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Eight adults of both genders and all races were studied in this double blind placebo controlled cross over study with randomization of the order of interventions. After 5 days each on low salt (about 1 gram/day) and high salt (about 6 grams/day)diet, with a washout period of at least four weeks in between, every subject was treated with Enalapril and Placebo on two consecutive days, followed by a Fenoldopam infusion for three hours, during which natriuresis and renal function testing were performed.

Official Title
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Paracrine Regulation of Renal Function by Dopamine in Normotensive Humans

Conditions
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Salt-sensitive Hypertension

Intervention / Treatment
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* Drug: Fenoldopam


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Volunteers Healthy Normal Blood Pressure Exclusion Criteria: Renal Impairment Obesity Salt sensitive increase in blood pressure

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Enalapril<br>2.5 mg every 12 hours for two doses | Drug: Fenoldopam<br>* Intravenous infusion at 0.5 mics/Kg/min for three hours<br>* Other names: Corlopam;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Urinary sodium excretion | All subjects received placebo/enalapril in a randomized counterbalanced fashion in both phases. Phase 1 was on low salt, while Phase 2 was on high salt. All subjects received a 3 hour fenoldopam infusion, during which time urinary sodium excretion was measured as the primary outcome bvariable. | During the trial: a 3 hour fenoldopam infusion | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Renal Plasma Flow | In order to explain physiologically the effects of fenoldopam on urinary sodium excretion on high and low salt diet, with and wothout enalapril, renal plasma flow was measured during the infusion using PAH clearance | During 3 hour fenoldopam infusion | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Salt, Balance, Renin Angiotensin System, Fenoldopam\blood Pressure, Sodium