Intradermal Administration of ATP Does Not Mitigate Tyramine-Stimulated Vasoconstriction in Human Skin

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dc.contributor.author Wingo, Jonathan E.
dc.contributor.author Brothers, R. Matthew
dc.contributor.author Coso, Juan Del
dc.contributor.author Crandall, Craig G.
dc.date.accessioned 2018-01-18T14:53:21Z
dc.date.available 2018-01-18T14:53:21Z
dc.identifier.uri http://ir.ua.edu/handle/123456789/3328
dc.description.abstract Cutaneous vasodilation associated with whole-body heat stress occurs via withdrawal of adrenergic vasoconstriction and engagement of cholinergic 'active' vasodilation, the latter of which attenuates cutaneous vasoconstrictor responsiveness. However, the precise neurotransmitter(s) responsible for this sympatholytic-like effect remain unknown. In skeletal muscle, ATP inhibits adrenergically mediated vasoconstriction. ATP also may be responsible for attenuating cutaneous vasoconstriction since it is coreleased from cholinergic neurons. The effect of ATP on cutaneous vasoconstrictor responsiveness, however, has not been investigated. Accordingly, this study tested the hypothesis that ATP inhibits adrenergically mediated cutaneous vasoconstriction. To accomplish this objective, four microdialysis probes were inserted in dorsal forearm skin of 11 healthy individuals (mean [+ or -] SD; 35 [+ or -] 11 years). Local temperature at each site was clamped at 34[degrees]C throughout the protocol. Skin blood flow was indexed by laser-Doppler flowmetry and was used to calculate cutaneous vascular conductance (CVC; laser-Doppler-derived flux/mean arterial pressure), which was normalized to peak CVC achieved with sodium nitroprusside infusion combined with local skin heating to ~42[degrees]C. Two membranes were perfused with 30 mM ATP, while the other two membranes were flow matched via administration of 2.8 mM adenosine to serve as control sites. After achieving stable baselines, 1 x [10.sup.-4] M tyramine was administered at all sites, while ATP and adenosine continued to be infused at their respective sites. ATP and adenosine infusion increased CVC from baseline by 35 [+ or -] 26% [CVC.sub.peak] units and by 36 [+ or -] 15% [CVC.sub.peak] units, respectively (P = 0.75). Tyramine decreased CVC similarly (by about one-third) at all sites (P < 0.001 for main effect and P = 0.32 for interaction). These findings indicate that unlike in skeletal muscle, ATP does not attenuate tyramine-stimulated vasoconstriction in human skin. en_US
dc.subject skin blood flow en_US
dc.subject thermoregulation en_US
dc.subject cutaneous vasodilation en_US
dc.subject laser-Doppler flowmetry en_US
dc.subject.lcsh Blood flow—Physiological aspects en_US
dc.subject.lcsh Body temperature—Regulation en_US
dc.subject.lcsh Skin en_US
dc.subject.lcsh Vasodilation en_US
dc.subject.lcsh Laser Doppler blood flowmetry en_US
dc.subject.lcsh Adenosine triphosphate—Physiological aspects en_US
dc.subject.lcsh Tyramine en_US
dc.title Intradermal Administration of ATP Does Not Mitigate Tyramine-Stimulated Vasoconstriction in Human Skin en_US


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