MELATONIN AND CORONARY HEART-DISEASE

The observation of raised nocturnal urinary norepinephrine excretion i n patients with coronary heart disease (CHD), together with results of animal experiments showing a suppression of sympathetic activity by m elatonin, were the reasons for this investigation. In 15 patients with CHD and 10 controls the concentrations of serum melatonin, serotonin and N-acetylserotonin were determined in samples gained by venopunctur e at 14.00 h and 02.00 h. The melatonin secretion was significantly lo wer at 02.00 h in the patients with CHD than in the controls. Moreover the serotonin concentration was significantly lower at 14.00 h in the patients with CHD, and somewhat, but not significantly, lower at 02.0 0 h than in the controls. On the other hand, the serum concentrations of N-acetylserotonin showed a tendency towards higher levels in the CH D patients than in the controls. The causes and consequences of the di minished secretion during the night in patients with CHD are discussed .