• Systolic and diastolic arterial pressures, heart rate, cardiac output, systemic vascular resistances [ Time Frame: Between administration time and 24 hours after treatment ] [ Designated as safety issue: No ]
• Central aortic pressures, Augmentation Index (Aix) [ Time Frame: Between administration time and 12 hours after treatment ] [ Designated as safety issue: No ]
• Arterial stiffness: Carotid-femoral Pulse Wave Velocity [ Time Frame: Between administration time and 12 hours after treatment ] [ Designated as safety issue: No ]
• Humeral diameter and distensibility [ Time Frame: Between administration time and 12 hours after treatment ] [ Designated as safety issue: No ]
• Plasma electrolytes, blood glucose, serum creatinine [ Time Frame: Between administration time and 24 hours after treatment ] [ Designated as safety issue: Yes ]
• Plasma renin, aldosterone, norepinephrine, epinephrine, hydrocortisone, fludrocortisone concentrations [ Time Frame: Between administration time and 24 hours after treatment ] [ Designated as safety issue: No ]
• Urinary electrolytes excretion [ Time Frame: Between administration time and 24 hours after treatment ] [ Designated as safety issue: No ]

Septic shock (associated with relative adrenal insufficiency) is characterized by decreased arterial responsiveness to catecholamines. The association of hydrocortisone and fludrocortisone has demonstrated an improvement in survival in septic shock patients. If hydrocortisone has shown to increase vascular responsiveness, the role of fludrocortisone remains to be elucidated. The purpose of our study is to investigate the effect of a physiological dose of fludrocortisone and/or hydrocortisone on phenylephrine-mean arterial pressure dose-response relationship in healthy volunteers with aldosterone suppression induced by intravenous sodium loading.

• Drug: Fludrocortisone
• Drug: Hydrocortisone
• Drug: Placebo of Fludrocortisone
• Drug: Placebo of Hydrocortisone

• Experimental: Fludrocortisone and Hydrocortisone
• Experimental: Fludrocortisone and placebo of Hydrocortisone
• Experimental: Placebo of Fludrocortisone and Hydrocortisone
• Placebo Comparator: Placebo of Fludrocortisone and placebo of Hydrocortisone

Inclusion Criteria:

• Men between 20 and 30 years
• Body Mass Index between 18 kg/m² and 25 kg/m²
• Normal clinical examination
• Normal biological variables
• Normal electrocardiogram and echocardiography
• Written, voluntary informed consent.

Exclusion Criteria:

• Any history of significant allergy
• Subjects with abnormal renal, pulmonary, cardiovascular, endocrine or hepatic function
• Medication during the study
• Alcohol consumption more than 30g/day or drug addiction
• Positive serology for hepatitis B virus (HBV), hepatitis C virus (HCV) or HIV.