An influence of melatonin on circadian blood pressure rhythm in hypertensive subjects with lack of nocturnal blood pressure decline

Abstract

Background Melatonin may influence autonomic nervous system and affect circadian blood pressure rhythm. The aim of the study was to investigate and influence of endogenous plasma melatonin an catecholamines on circadian blood pressure in hypertensive subjects with lack of nocturnal blood pressure decline.

Material and methods The study included 21 dippers (D) (M 7/F 14, age 55.4 ± 10.7 yrs) and 12 non-dippers (ND) (M 4/F 8 age 59 ± 6.4 yrs) divided according to systolic and mean blood pressure nocturnal decline < 10% of daytime values. Ambulatory BP monitoring (SpaceLabs 90207) was performed and blood samples for melatonin (MT) (RIA, pg/mL), noradrenaline (NA) (HPLC, pg/mL) and adrenaline (A) (HPLC, pg/mL) determination were withdrawn every 4 hours during day and night time.

Results MT was significantly lower in ND as compared to D at 02 AM, (19.7 ± 14.4 vs 63.3 ± 33.2; P < 0.001, respectively), 06 AM (20.0 ± 12.2 vs 45.1 ± 25.0; P < 0.004, respectively) and 02 PM (5.4 ± 2.3 vs 7.6 ± 2.3, P < 0.015, respectively) while no differences were found in MEL between groups at 10 AM (6.5 ± 2.2 vs 8.4 ± 7.0), 06 PM (5.9 ± 2.3 vs 8.6 ± 5.1) and 10PM (15.1 ± 14.5 vs 26.4 ± 25.4, respectively). NA as well as A were similar in ND and D.

Conclusions Dippers and non-dippers are characterized by different diurnal profile of melatonin. Melatonin may play a role in regulation of circadian blood pressure rhythm, however its influence is not exerted by catecholamines.