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Quantification and Interpretation of Nitric Oxide-Dependent Cutaneous Vasodilation During Local Heating
Journal article   Peer reviewed

Quantification and Interpretation of Nitric Oxide-Dependent Cutaneous Vasodilation During Local Heating

S Tony Wolf, Gabrielle A Dillon, Lacy M Alexander, W Larry Kenney and Anna E Stanhewicz
Journal of applied physiology (1985), Vol.137(5), pp.1418-1424
11/01/2024
DOI: 10.1152/japplphysiol.00558.2024
PMCID: PMC11573251
PMID: 39417818

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Abstract

Human cutaneous microdialysis approaches for assessing nitric oxide (NO)-dependent blood flow include local heating (LH) of the skin until a plateau is reached, followed by infusion of a NO synthase inhibitor such as L-NAME; however, varied methods of quantifying and expressing NO-dependent vasodilation can obfuscate data interpretation and reproducibility. We retrospectively assessed NO-dependent vasodilation during LH to 39°C or 42°C, calculated as the: (1) absolute contribution of the NO-dependent component (along with baseline and the non-NO-dependent component) to the total cutaneous vascular conductance (CVC) response to LH, normalized to maximal CVC (%CVC ); (2) difference in %CVC (∆%CVC ) between the LH plateau and post-NO inhibition (L-NAME plateau; ∆%CVC =LH plateau-L-NAME plateau); (3) percentage of the LH plateau attributable to ∆%CVC (%Plateau = ∆%CVC /LH plateau*100); and (4) %Plateau when correcting for baseline. The LH plateaus during 39°C and 42°C were 48±17 %CVC (9±5% baseline; 2±4% non-NO-dependent; 36±15% NO-dependent) and 88±10 %CVC (15±8% baseline; 9±10% non-NO-dependent; 64±13% NO-dependent), respectively. The absolute contributions of the non-NO-dependent and NO-dependent components of the response (p<0.0001) and the ∆%CVC (66±14% vs. 38±15%) were greater during 42°C compared with 39°C (all p≤0.02); however, there were no differences between the two protocols in %Plateau (75±13% vs. 80±10%; p=0.57) or %Plateau (88±14% vs. 95±8%; p=0.31). For both protocols, the values were greater for %Plateau versus ∆%CVC and %Plateau (p≤0.0001), and for %Plateau versus ∆%CVC (p≤0.05). Quantification of NO-dependent skin vasodilation responses to LH is dependent upon the mathematical approach and verbal description, which can meaningfully impact data interpretation and reproducibility.
endothelial function intradermal microdialysis skin blood flow vascular function nitric oxide

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