scholarly journals Axon Reflex Vasodilatation in Human Skin Measured by a Laser Doppler Technique.

1991 ◽  
Vol 41 (5) ◽  
pp. 693-702 ◽  
Author(s):  
Hiroshi IZUMI ◽  
Keishiro KARITA
Keyword(s):  
Human Skin ◽  
Laser Doppler ◽  
Axon Reflex ◽  
Doppler Technique

No α-adrenoreceptor-induced C-fiber activation in healthy human skin

2004 ◽  
Vol 96 (4) ◽  
pp. 1380-1384 ◽  
Author(s):  
Sebastian Zahn ◽  
Stefan Leis ◽  
Christoph Schick ◽  
Martin Schmelz ◽  
Frank Birklein
Keyword(s):  
Healthy Volunteers ◽  
Human Skin ◽  
Drug Effects ◽  
Laser Doppler ◽  
Doppler Imaging ◽  
Chemical Stimulus ◽  
Skin Area ◽  
Laser Doppler Imaging ◽  
Healthy Human ◽  
Axon Reflex

In healthy volunteers, flare responses induced by norepinephrine (NE) iontophoresis have been observed. However, as NE iontophoresis is a combined electrical and chemical stimulus axon, reflexes cannot be directly linked to pharmocological activity of NE. Different concentrations of NE, clonidine (CL), and phenylephrine (PE) (NE: 10-10-10-3 M; CL and PE: 10-8-10-3 M) were applied via intradermal microdialysis fibers into the skin of healthy volunteers. Simultaneously, skin blood flow was visualized by laser-Doppler imaging scans and quantified in a vasoconstriction skin area directly above the membranes to control drug effects and in expected axon reflex vasodilation areas that were 0.75 cm apart. NE, PE, and CL caused dose-dependent vasoconstriction. However, neither in the presumed axon reflex areas (quantitative analysis) nor on laser-Doppler imaging pictures (qualitative analysis) were any vasodilation observed. Even at concentrations causing maximum vasoconstriction (10-3 M for any drug), no vasodilation was induced. Our results indicate that, in healthy human skin, exogenously supplied α-adrenoreceptor agonists alone do not activate nociceptors sufficiently to induce axon reflex flare.

scholarly journals Ossiculoplasty Efficacy Monitored by ECoG-Laser-Doppler Technique

2011 ◽  
Vol 145 (2_suppl) ◽  
pp. P222-P223
Author(s):  
Kazimierz Niemczyk ◽  
Robert Bartoszewicz ◽  
Jacek Sokolowski ◽  
Krzysztof F. Morawski
Keyword(s):  
Laser Doppler ◽  
Doppler Technique

A Laser-Doppler Investigation of the Flow inside a Backswept, Closed, Centrifugal Impeller

1979 ◽  
Vol 21 (1) ◽  
pp. 1-6 ◽  
Author(s):  
D. Adler ◽  
Y. Levy
Keyword(s):  
Flow Field ◽  
Flow Fields ◽  
Fundamental Difference ◽  
Laser Doppler ◽  
Centrifugal Impeller ◽  
Doppler Technique

A laser-Doppler technique is successfully applied to measure the flow field inside a closed, backswept impeller, through a rotating window. Results show that, in contrast to the flow in many radial-exit impellers, the flow in the backswept impeller is stable and attached. Further, comparison with an open impeller demonstrates the fundamental difference in the flow fields near the shroud.

Potent vasoactive properties of endothelin 1 in human skin

1991 ◽  
Vol 70 (1) ◽  
pp. 260-266 ◽  
Author(s):  
D. C. Crossman ◽  
S. D. Brain ◽  
R. W. Fuller
Keyword(s):  
Blood Flow ◽  
Endothelial Cell ◽  
Human Skin ◽  
Intradermal Injection ◽  
Local Response ◽  
Axon Reflex ◽  
Endothelin 1 ◽  
Calcitonin Gene ◽  
H1 Antagonist ◽  
Dose Dependent

The effect of the endothelial cell-derived peptide endothelin 1 was investigated in human skin. Intradermal injection of endothelin 1 (1–100 pmol) caused a dose-dependent area of pallor that was associated with a significant reduction in basal skin blood flow, measured by laser-Doppler blood flowmeter (with 1 pmol endothelin, P = 0.012, analysis of variance). The coadministration of endothelin 1 (1–100 pmol) with the neuropeptide vasodilator calcitonin gene-related peptide (CGRP) inhibited the vasodilator response to CGRP (10 pmol) by up to 82.7 +/- 9.2% (with 100 pmol endothelin, P less than 0.001). The response of the prostanoid vasodilator prostaglandin E2 (10 pmol) was inhibited by endothelin in a similar manner. In addition to the vasoconstrictor effects, endothelin 1 produced a dose-dependent flare that surrounded the area of pallor, and this was associated with a significant increase in blood flow (P less than 0.05) within the flare area. The H1 antagonist terfenadine (120 mg po) significantly reduced the flare area associated with endothelin 1: flare 5 min after intradermal endothelin (10 pmol, placebo treated), 668 +/- 405 mm2; terfenadine treated, 201 +/- 257 mm2 (P less than 0.05). The flare was also significantly attenuated when endothelin (10 pmol) was injected into local anesthetic-treated skin. Thus intradermal injection of endothelin in humans causes long-lasting vasoconstriction at the site of injection and a surrounding flare. Results suggest that the flare component is partially histamine dependent and the result of an axon reflex. This study demonstrates the potent activity of endothelin in human skin. It is possible that endothelin could be relevant to the local response of skin to injury.

The acute impact of local cooling versus local heating on human skin microcirculation using laser Doppler flowmetry and tissue spectrophotometry

Burns ◽  
2020 ◽  
Vol 46 (1) ◽  
pp. 104-109 ◽  
Author(s):  
Dominik Bender ◽  
Stephanie Tweer ◽  
Frank Werdin ◽  
Jens Rothenberger ◽  
Adrien Daigeler ◽  
...  
Keyword(s):  
Human Skin ◽  
Laser Doppler Flowmetry ◽  
Local Heating ◽  
Laser Doppler ◽  
Local Cooling ◽  
Skin Microcirculation ◽  
Doppler Flowmetry

Effects of chronic sympathectomy on locally mediated cutaneous vasodilation in humans

2002 ◽  
Vol 92 (2) ◽  
pp. 685-690 ◽  
Author(s):  
Nisha Charkoudian ◽  
John H. Eisenach ◽  
John L. D. Atkinson ◽  
Robert D. Fealey ◽  
Michael J. Joyner
Keyword(s):  
Nitric Oxide ◽  
Human Skin ◽  
Lower Body Negative Pressure ◽  
Local Heating ◽  
Sympathetic Innervation ◽  
Sensory Nerve ◽  
Laser Doppler ◽  
Sympathetic Denervation ◽  
Vascular Conductance ◽  
Local Warming

In human skin, the vasodilator response to local heating includes a sensory nerve-dependent peak followed by a nadir and then a slower, nitric oxide-mediated, endothelium-dependent vasodilation. To investigate whether chronic sympathectomy diminishes this endothelium-dependent vasodilation, we studied individuals who had previously undergone surgical T2 sympathectomy ( n = 9) and a group of healthy controls ( n = 8). We assessed the cutaneous vascular response (laser-Doppler) to 30 min of local warming to 42.5°C on the ventral forearm (no sympathetic innervation) and the lower legs (sympathetic nerves intact). Lower body negative pressure (LBNP) was measured to confirm sympathetic denervation. During local warming in sympathectomized individuals, vascular conductance reached an initial peak at both sites [achieving 1.73 ± 0.22 laser-Doppler units (LDU)/mmHg in the forearm and 1.92 ± 0.21 LDU/mmHg in the leg]. It then decreased to a nadir in the innervated leg [to 1.77 ± 0.23 LDU/mmHg ( P < 0.05)] but not in the sympathectomized arm (1.69 ± 0.21 LDU/mmHg; P > 0.10). The maximal vasodilation seen during the slower phase was not different between limbs or between groups. Furthermore, LBNP caused a 44% reduction in forearm vascular conductance (FVC) in control subjects, but FVC did not decrease significantly in sympathectomized individuals, confirming sympathetic denervation. These data indicate that endothelial function in human skin is largely preserved after sympathectomy. The altered pattern of the response suggests that the nitric oxide-dependent portion may be accelerated in sympathectomized limbs.

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