Neurohypophyseal dysfunction during septic shock.

Septic shock is characterized by vasodilation and hypotension despite increased vasoconstrictors. While nitric oxide is known to be responsible for vasodilation, failure of vascular smooth muscle to constrict may be due in part to low plasma levels of vasopressin, a neurohypophyseal hormone. In the initial phase of septic shock, vasopressin concentration usually increases but then decreases to a significantly lower concentration after onset of septic shock. In this review, we discuss the neural mechanisms for the regulation of vasopressin secretion during septic shock.