Effect of chronic stress and sleep deprivation on both flow-mediated dilation in the brachial artery and the intracellular magnesium level in humans.
BACKGROUND
Chronic mental and physical stress has been suggested to be a trigger for cardiovascular events. In addition, a reduction in levels of intracellular magnesium has been reported to cause vasoconstriction while enhancing platelet-dependent thrombosis.


OBJECTIVE
The purpose of this study was to investigate whether chronic stress affects endothelial function and intracellular magnesium levels in humans.


METHODS
Flow-mediated dilation (endothelium-dependent vasodilation) and sublingual nitroglycerin-induced dilation (0.3 mg, endothelium-independent vasodilation) were measured in the brachial artery in 30 healthy male college students, aged 22 +/- 1 years, using high-resolution ultrasound both before and immediately after a 4-week final term examination period. Erythrocyte magnesium concentration was measured simultaneously. All students had chronic sleep deprivation for 4 weeks, during which sleep lasted < 80% of that on ordinary days; in addition, the students were under great stress to pass the examination. This condition was considered to be chronic stress.


RESULTS
Chronic stress decreased flow-mediated dilation and erythrocyte magnesium concentration (from 7.4 +/- 3.0 to 3.7 +/- 2.3%, p < 0.05; from 5.7 +/- 0.4 to 5.5 +/- 0.4 mg/ml, p < 0.05, respectively). The change in flow-mediated dilation correlated significantly with that of the erythrocyte magnesium concentration (r = 0.43, p < 0.05), but not with nitroglycerin-induced dilation.


CONCLUSIONS
Chronic stress was found to attenuate endothelial function, which may also be associated with a reduction in the intracellular magnesium level in humans.
Takase
Bonpei
B
National Defense Medical College, Internal Medicine-1, Tokorozawa, Saitama, Japan. bonpeit@me.ndmc.ac.jp
Akima
Takashi
T
Uehata
Akimi
A
Ohsuzu
Fumitaka
F
Kurita
Akira
A
D000328:Adult; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology*; D002908:Chronic Disease; D004730:Endothelium, Vascular / Q000503:physiopathology; D006801:Humans; D008274:Magnesium / Q000097:blood*; D008275:Magnesium Deficiency / Q000209:etiology / Q000503:physiopathology; D008297:Male; D005996:Nitroglycerin; D012039:Regional Blood Flow; D012892:Sleep Deprivation / Q000150:complications / Q000503:physiopathology*; D013312:Stress, Physiological / Q000150:complications / Q000503:physiopathology*; D014463:Ultrasonography; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D005996:Nitroglycerin; D008274:Magnesium