No effect of systemic isocapnic hypoxia on α-adrenergic vasoconstrictor responsiveness in human skin.
Acta Physiol (Oxf)
; 201(3): 339-47, 2011 Mar.
Article
in En
| MEDLINE
| ID: mdl-20946237
ABSTRACT
UNLABELLED Hypoxia impairs body temperature regulation and abolishes the decline in skin temperature associated with cold exposure, suggesting that cutaneous vasoconstriction is impaired. AIM:
The purpose of this study was to test the hypothesis that cutaneous vasoconstriction to intradermal tyramine, an index of post-junctional vasoconstrictor responsiveness, is reduced during hypoxia.METHODS:
Twelve subjects (six males, six females) had three microdialysis fibres placed in the ventral forearm. Fibres received either lactated ringers, 5 mm yohimbine (α-adrenergic blockade), or 10.5 µm BIBP-3226 (to antagonize neuropeptide Y Y(1) receptors). Skin blood flow was assessed at each site (laser-Doppler flowmetry) and cutaneous vascular conductance (CVC) was calculated (red blood cell flux/mean arterial pressure) and scaled to baseline. Vasoconstrictor responses to tyramine (173 µm) were tested during normoxia and steady-state isocapnic hypoxia (SaO(2) = 80%) in random order.RESULTS:
During normoxia, tyramine reduced CVC by 56.0±5.6 and 50.3±8.0% in control and BIBP-3226 sites (both P<0.05 vs. pre-tyramine; P=0.445 between sites) whereas CVC in the yohimbine site did not change (P=0.398 vs. pre-tyramine). During isocapnic hypoxia, tyramine reduced CVC by 55.9±5.1 and 54.2±5.4% in control and BIBP-3226 sites (both P<0.05 vs. pre-tyramine; P=0.814 between sites) whereas CVC was unchanged in the yohimbine site (P=0.732 vs. pre-tyramine). Isocapnic hypoxia did not affect vasoconstrictor responses at any site (all P>0.05 vs. normoxia).CONCLUSION:
We conclude that post-junctional α-adrenergic vasoconstrictor responsiveness is not affected by hypoxia in non-acral skin.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Skin Physiological Phenomena
/
Vasoconstriction
/
Blood Flow Velocity
/
Receptors, Adrenergic, alpha
Limits:
Adult
/
Female
/
Humans
/
Male
Language:
En
Journal:
Acta Physiol (Oxf)
Journal subject:
FISIOLOGIA
Year:
2011
Type:
Article
Affiliation country:
United States