| α-Adrenergic vasoconstrictor responsiveness is preserved in the heated human leg. | |
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MedLine Citation:
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PMID: 20693291 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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This study tested the hypothesis that passive leg heating attenuates α-adrenergic vasoconstriction within that limb. Femoral blood flow (FBF, femoral artery ultrasound Doppler) and femoral vascular conductance (FVC, FBF/mean arterial blood pressure), as well as calf muscle blood flow (CalfBF, ¹³³xenon) and calf vascular conductance (CalfVC) were measured during intra-arterial infusion of an α₁-adrenoreceptor agonist, phenylephrine (PE, 0.025 to 0.8 μg kg₋₁ min₋₁) and an α₂-adrenoreceptor agonist, BHT-933 (1.0 to 10 μg kg₋₁ min₋₁) during normothermia and passive leg heating (water-perfused pant leg). Passive leg heating (∼46◦C water temperature) increased FVC from 4.5 ± 0.5 to 11.9 ± 1.3 ml min₋₁ mmHg₋₁ (P < 0.001). Interestingly, CalfBF (1.8±0.2 vs. 2.8±0.3mlmin₋₁ (100 g)₋₁) and CalfVC (2.0±0.3 vs. 3.9±0.5mlmin₋₁ (100 g)₋₁ mmHg₋₁ ×100) were also increased by this perturbation (P <0.05 for both). Infusion of PE and BHT-933 resulted in greater absolute decreases in FVC during leg heating compared to normothermic conditions (maximal decreases in FVC during heating vs. normothermia: PE: 7.8 ± 1.1 vs. 2.8 ± 0.5 ml min₋₁ mmHg₋₁; BHT-933: 8.6 ± 1.7 vs. 2.1 ± 0.4 ml min₋₁ mmHg₋₁; P < 0.01 for both). However, the nadir FVC during drug infusion was higher during passive leg heating compared to normothermic conditions (FVC at highest dose of respective drugs during heating vs. normothermic conditions: PE: 3.7 ± 0.4 vs. 2.0 ± 0.3 ml min₋₁ mmHg₋₁; BHT-933: 3.8 ± 0.2 vs. 2.1 ± 0.3 ml min₋₁ mmHg₋₁; P < 0.001 for both). Leg heating did not alter the responsiveness of CalfBF or CalfVC to either PE or BHT-933. Taken together, these observations suggest that local heating does not decrease α-adrenergic responsiveness.However, heat-induced vasodilatation opposes α-adrenergic vasoconstriction. Furthermore, passive heating of a limb causes not only an increase in skin blood flow but also in muscle blood flow. |
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Authors:
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David M Keller; Mikael Sander; Bente Stallknecht; Craig G Crandall |
Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The Journal of physiology Volume: 588 ISSN: 1469-7793 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 2010 Oct |
Date Detail:
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Created Date: 2010-10-06 Completed Date: 2011-01-21 Revised Date: 2012-04-27 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: England |
Other Details:
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Languages: eng Pagination: 3799-808 Citation Subset: IM |
Affiliation:
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Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, TX 75231, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adrenergic alpha-1 Receptor Agonists
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pharmacology Adrenergic alpha-2 Receptor Antagonists / pharmacology Adrenergic alpha-Agonists / pharmacology Adult Azepines / pharmacology Blood Pressure / physiology Body Temperature / physiology Dose-Response Relationship, Drug Hot Temperature* Humans Leg / blood supply* Male Muscle, Skeletal / blood supply, physiology Phenylephrine / pharmacology Receptors, Adrenergic, alpha / drug effects, physiology* Regional Blood Flow / drug effects, physiology Ultrasonography, Doppler Vasoconstriction / drug effects, physiology* Xenon Radioisotopes / diagnostic use Young Adult |
| Grant Support | |
ID/Acronym/Agency:
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84072//PHS HHS; NHLBI 082426//PHS HHS; NHLBI 61388//PHS HHS; R01 HL061388-08/HL/NHLBI NIH HHS; R01 HL061388-09/HL/NHLBI NIH HHS; R01 HL061388-12/HL/NHLBI NIH HHS; R01 HL084072-02/HL/NHLBI NIH HHS; R01 HL084072-03/HL/NHLBI NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Adrenergic alpha-1 Receptor Agonists; 0/Adrenergic alpha-2 Receptor Antagonists; 0/Adrenergic alpha-Agonists; 0/Azepines; 0/Receptors, Adrenergic, alpha; 0/Xenon Radioisotopes; 36067-73-9/B-HT 933; 59-42-7/Phenylephrine |
| Comments/Corrections | |
Comment In:
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J Physiol. 2010 Oct 15;588(Pt 20):3847-8
[PMID:
20952374
]
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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