Blood pressure in acute and chronic vasopressin excess: studies of malignant hypertension and the syndrome of inappropriate antidiuretic hormone secretion.

We studied 29 patients with malignant hypertension and 28 patients with the syndrome of inappropriate antidiuretic hormone secretion to assess the relation of plasma vasopressin to blood pressure in states of acute and chronic vasopressin excess. In the patients with malignant hypertension, vasopressin levels were elevated (13 +/- 2 pg per milliliter. [+/- S.E.M.]) but did not correlate with arterial pressure; however, in normal volunteers, blood pressure did not rise when vasopressin was increased beyond these levels through infusion of the peptide. In the patients with inappropriate antidiuretic hormone secretion, blood pressure was not elevated, but vasopressin was raised (39 +/- 7 pg per milliliter) and did not correlate with systolic or diastolic pressure. These data do not support the concept that an acute or chronic excess of vasopressin makes an important contribution to the regulation of blood pressure.