Dopexamine is a structural and synthetic analog of dopamine that exerts systemic and gut vasodilation and stimulates cardiac contraction. In experimental models, dopexamine has been shown to exert anti-inflammatory properties and to protect the hepatic ultra structure. The combination of dopexamine and norepinephrine could therefore constitute an interesting alternative in treating septic shock patients. This study will test the efficacy (on gastric mucosal blood flow, hepatic damage and oxidative stress) and safety of the combination of dopexamine and norepinephrine (compared to those of epinephrine alone) in the treatment of patients with septic shock.