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Acute influence of oral vitamin C on the vasoconstrictor responses to local cooling and tyramine in human skin
Author(s) -
Yamazaki Fumio
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.lb726
Subject(s) - tyramine , vasoconstriction , vasodilation , adrenergic , medicine , endocrinology , forearm , chemistry , anatomy , receptor
It has been reported that orally ingesting vitamin C (Asc) enhanced the cutaneous vasoconstrictor response to local cooling (LC). In this study, we examined whether the increased vasoconstrictor response caused by oral Asc is due to the adrenergic system. The release of neurotransmitters from adrenergic nerves in forearm skin was blocked locally by iontophoresis of bretylium tosylate (BT). Skin blood flow (SkBF) was measured by laser‐Doppler flowmetry at BT‐treated and untreated sites. The skin sites were locally cooled from 34 to 24°C at −1°C/min and maintained at 24°C for 10 min before (Pre) and 1.5 h after (Post) oral Asc (2g single dose) supplementation. Cutaneous vascular conductance (CVC) was calculated as the ratio of SkBF to blood pressure and expressed relative to the baseline value before LC. Oral Asc enhanced (P<0.05) the reductions in CVC at untreated sites but did not change the responses at BT‐treated sites during LC. To further examine whether adrenergically mediated vasoconstriction is enhanced by oral Asc, 0.1mM tyramine was administered using intradermal microdialysis in the forearm skin at 34°C in the Pre and Post periods. Oral Asc increased (P<0.05) the tyramine‐induced reduction in CVC. These findings suggest that oral Asc acutely enhances the cutaneous vasoconstrictor responses to LC through the modification of adrenergic sympathetic mechanisms.