OBJECTIVETo investigate the effect of plasma neuropeptide Y (NPY), neurotensin (NT) and their relationships on the diurnal rhythm of BP and target organ damage for essential hypertension.

METHODSAmbulatory BP monitoring (ABPM) for 24 hours was performed in ninety patients with essential hypertension and thirty healthy subjects. The patients were divided into two groups: 55 dippers and 35 non-dippers according to the ABPM results. Plasma NPY and NT levels in subjects were measured at 8:00, 16:00 and 2:00 o'clock by using radioimmunoassay method. Target organ functions were measured.

RESULTSThe plasma NPY level was higher and NT was lower in patients with hypertension those in normal controls (P < 0.001). Compared with dippers, non-dippers had a higher NPY and a lower NT plasma levels, especially appearing at 2:00 o'clock. The patients with left ventricular hypertrophy, stroke or kidney damage had a higher NPY and a lower NT levels compares with those without target organ damage.

CONCLUSIONThe changes in plasma NPY and NT may contribute to disturbance of the diurnal rhythm of blood pressure in patients with essential hypertension, especially in those with target organ damages, which may serve as a pathophysiologic mechanism for target organ damages in hypertension.