Effects of chronic administration of vitamin E on haemodynamic responses to postural stress or cold pressor test in apparently healthy young men.
OBJECTIVE
We sought to investigate the possible effect of chronic administration of vitamin E on haemodynamic responses to sympathetic stimulation and to test the hypothesis that chronic administration of vitamin E increases susceptibility to orthostatic intolerance.


METHODS
Sympathetic stimulation was assessed by responses in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), forearm blood flow (FBF; venous occlusion plethysmography) and forearm vascular resistance (FVR) evoked by postural stress (600 head-up tilt; HUT) or cold pressor test (CPT) in 30 healthy young men before and after 4 weeks of vitamin E administration. CPT was induced by immersing a hand in water at 40 degrees C for 2 minutes.


RESULTS
Administration of vitamin E reduced SBP (p<0.001), DBP (p<0.001), MAP (p<0.001), HR (p<0.001) and FVR (p<0.05) but increased FBF (p<0.01). Before vitamin E administration HUT increased HR (p<0.001). Conversely, HUT led to a decrease in HR (p<0.05) after vitamin E administration. The decreases in SBP (p<0.05) and FBF (p<0.05) with concomitant increases in DBP (p<0.001), MAP (p<0.001) and FVR (p<0.001) induced by HUT before vitamin E administration, were similar to those induced by HUT after vitamin E administration. The increases in SBP (p<0.001), DBP (p<0.001), MAP (p<0.001), HR (p<0.05), FVR (p<0.001) and a decrease in FBF (p<0.001) induced by CPT before vitamin E administration, were attenuated following vitamin E administration in these subjects.


CONCLUSIONS
These results demonstrate that chronic administration of vitamin E significantly reversed HUT-induced tachycardia and prevented CPT-induced vascular and pressor responses. These findings suggest that vitamin E may exert cardioprotective effect presumably through enhanced cardiac vagal tone that may not be associated with poor orthostatic tolerance in young men.
Olatunji
L A
LA
Department of Physiology, College of Health Sciences, University of Ilorin, P.M.B. 1515, Ilorin 240001, Nigeria.
Soladoye
A O
AO
D000975:Antioxidants / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D003080:Cold Temperature; D019587:Dietary Supplements; D005542:Forearm / Q000098:blood supply*; D006801:Humans; D008297:Male; D054971:Orthostatic Intolerance; D011187:Posture / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D013312:Stress, Physiological; D013564:Sympathetic Nervous System / Q000502:physiology; D018667:Tilt-Table Test; D014655:Vascular Resistance / Q000187:drug effects* / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology; D014810:Vitamin E / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology*
D000975:Antioxidants; D014815:Vitamins; D014810:Vitamin E