Defect in the excretion of a vasoactive polypeptide fraction A possible genetic marker of primary hypertension.

A polypeptide fraction isolated from the urine of normotensive subjects lowers the blood pressure (BP) in a rabbit bioassay (mean BP decrease 33.8% +/- 0.6%, SEM). Patients with primary hypertension exhibit reduced or no activity (mean BP decrease 8.8% +/- 1.2%). In contrast, patients with secondary forms of hypertension show activity like normotensives (mean BP decrease 33.4% +/- 1.0%). The results of the bioassay in the two patient groups correlate well with the family incidence of hypertension (68% and 37% for primary and secondary hypertension respectively). Cases with borderline hypertension fall into two groups; a larger one with vasoactivity inthe bioassay and lower family incidence of hypertension; and a smaller group reacting like patients with primary hypertension. Only the latter group may represent an initial stage of primary hypertension. In normotensive children and young men, an inactive fraction was found in 31% and 28% respectively. These inactive groups had twice the family incidence of hypertension compared to the groups with vasoactivity. These results suggest the existence of a possible genetic marker of primary hypertension and may offer the possibility to detect the disease before its manifestation.