Elevated plasma concentration of neuropeptide Y in adolescents with primary hypertension

Neuropeptide Y (NPY) has been recently characterised as a circulating vasoconstrictor peptide which is co-stored with noradrenaline (NA) in sympathetic neurons. We measured NPY by radioimmunoassay and NA by HPLC in plasma of ten healthy volunteers (23-27 years of age) during bicycle ergometry and found a rapid increase of both NPY and NA during exercise. NPY rose from 1.3 +/- 0.5 to 9.6 +/- 7.8 pmol/l and NA from 1.3 +/- 0.3 to 10.8 +/- 5.6 mnol/l (mean +/- SD). Following maximal exercise NA disappeared more rapidly from plasma than NPY. Compared with these healthy volunteers, plasma NPY was found to be elevated in 23 children and adolescents aged 9-18 years with borderline primary hypertension (NPY 3.1 +/- 1.7 pmol/l, P < 0.01). Basal NPY was also elevated when compared with 21 age-matched pediatric controls (P < 0.05). The bicycle ergometry protocol performed in 23 patients separated ten adolescents with normal basal and exercise blood pressure from 13 with high BP also during ergometry. In the latter group, NPY rose to 11.9 +/- 7.3 pmol/l and NA to 12.3 +/- 8.6 nmol/l during exercise. Treatment of the hypertensive patients with the beta-adrenergic blocker atenolol (50 mg per day) lowered basal and exercise BP. Heart rate fell during atenolol treatment from 92 +/- 19 to 72 +/- 15 beats/min. Treatment did not alter plasma concentrations under basal conditions and during exercise (NPY from 2.8 +/- 2.1 to 11.7 +/- 5.3 pmol/l and NA from 2.0 +/- 0.8 to 15.6 +/- 14.1 nmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)