Ray CA.

Circulation. 1999 Nov 2; 100: I-136.

Penn State Univ, Hershey, PA, USA.

Previous studies have suggested that melatonin may alter sympathetic outflow in humans. The purpose of the present study was to determine the effect of melatonin on sympathetic nerve activity at rest and during orthostatic stress in humans. Fifty minutes after receiving a 3 mg tablet of melatonin or placebo (separate day), muscle sympathetic nerve activity (MSNA), arterial pressure, and heart rate were measured for 10 min at rest and during 5 min of lower body negative pressure (LBNP) at -10 and -40 mmHg (n = 11). MSNA at rest was increased from 22 +/- 2 bursts during the placebo trial to 28 +/- 2 bursts/min with melatonin (p < 0.05). Heart rate was significantly lower with melatonin (59 +/- 3 to 63 +/- 4 beats/min) whereas mean arterial pressure was not significantly different between trials (93 +/- 3 mmHg). During LBNP, MSNA responses were attenuated during both the -10 and -40 mmHg levels (p < 0.03). Specifically, for the placebo trial MSNA increased 33 +/- 8% and 251 +/- 70% during -10 and -40 mmHg, respectively, but only increased 8 +/- 7% and 111 +/- 35% during -10 and -40 mmHg, respectively, following melatonin. These findings indicate that melatonin can alter sympathetic outflow at rest and impair reflex sympathetic changes to orthostatic stress in humans.

Publication Types:

• Meeting Abstracts

Keywords:

• Animals
• Autonomic Pathways
• Bed Rest
• Blood Pressure
• Heart Rate
• Humans
• Lower Body Negative Pressure
• Melatonin
• Muscles
• Reflex
• Rest
• Salicylates
• Stress
• Sympathetic Nervous System
• bismuth subsalicylate
• NASA Discipline Cardiopulmonary
• Non-NASA Center

Other ID:

• 20601157

UI: 102184897

From Meeting Abstracts