Pressor response to norepinephrine in essential hypertension. A study in families.

Study of pressor response to graded, increased doses of infused norepinephrine in patients with essential hypertension, their normotensive siblings, and normotensive control subjects unrelated to the patients and without a family history of hypertension indicated an increased response in the two former groups. Comparison of the dose-response curves in the three groups showed that the difference in response was due to a reduced threshold to norepinephrine in patients and their siblings and not to differences in the slopes of the dose-response curves. These alterations were not paralleled by differences in heart rate responses.