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

Paracrine Regulation of Renal Function by Dopamine in Normotensive Humans

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.

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.

Inclusion Criteria:

• Volunteers
• Healthy
• Normal Blood Pressure

Exclusion Criteria:

• Renal Impairment
• Obesity
• Salt sensitive increase in blood pressure