Elevated Neuropeptide Y Plasma Concentration in Non-dippers With Essential Hypertension

Abstract

Background The aim of the study was to investigate the relationship between biochemical indices of sympathetic activity and diurnal blood pressure rhythm in patients with essential hypertension.
Material and methods The study included 68 patients with mild-to-moderate essential hypertension (EH) (mean age 40 ± 1 yrs; 20 F, 48 M). The control group consisted of 25 healthy normotensive volunteers (C) (mean age 38 ± 1 yrs; 8 F, 17 M). Twenty-four hour ambulatory blood pressure monitoring was obtained using the SpaceLabs 90207. Blood samples for NPY and catecholamines were taken. Urine for catecholamines determination was collected.
Results In patients with EH NPY, plasma concentration was significantly higher as compared to C. Plasma catecholamine and urine catecholamine excretion was similar in patients with EH and in C. Patients with EH were divided into two groups: dippers (46 pts) and non-dippers (22 pts). In EH, the NPY plasma concentration was significantly higher in non-dippers than in dippers (10,6 ± 1 vs. 8,6 ± 1 fmol/mL, respectively, p < 0,05). No differences in plasma catecholamine and urine catecholamine excretion were found between dippers and non-dippers. Urine catecholamine excretion during nighttime was significantly lower as compared to day-time excretion in dippers and non-dippers. No differences between the groups were found with regard to day-time and night-time catecholamine excretion.
Conclusion NPY may play a role in diurnal blood pressure rhythm disturbances in non-dippers with EH. Catecholamines appear not to influence non-dipper phenomenon.