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 HPL C in plasma of ten healthy volunteers (23-27 years of age) during bicy cle ergometry and found a rapid increase of both NPY and NA during exe rcise. 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 exerc ise NA disappeared more rapidly from plasma than NPY. Compared with th ese healthy volunteers, plasma NPY was found to be elevated in 23 chil dren and adolescents aged 9-18 years with borderline primary hypertens ion (NPY 3.1 +/- 1.7 pmol/l, P < 0.01). Basal NPY was also elevated wh en compared with 21 age-matched pediatric controls (P < 0.05). The bic ycle ergometry protocol performed in 23 patients separated ten adolesc ents with normal basal and exercise blood pressure from 13 with high B P 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 th e hypertensive patients with the beta-adrenergic blocker atenolol (50 mg per day) lowered basal and exercise BP. Heart rate fell during aten olol treatment from 92 +/- 19 to 72 +/- 15 beats/min. Treatment did no t alter plasma concentrations under basal conditions and during exerci se (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). These results suggest that NPY is stimulat ed during the early course of primary hypertension in adolescents.