Quantification and interpretation of nitric oxide-dependent cutaneous vasodilation during local heating

Area of Science:

• Physiology
• Dermatology
• Cardiovascular Research

Background:

• Human cutaneous microdialysis with local heating (LH) and nitric oxide (NO) synthase inhibition is used to assess NO-dependent blood flow.
• Varied methods for quantifying NO-dependent vasodilation can lead to inconsistent data interpretation and reproducibility.
• Standardizing these quantification methods is crucial for reliable research outcomes in microvascular function studies.

Purpose of the Study:

• To retrospectively assess NO-dependent vasodilation during LH at 39°C and 42°C.
• To compare four distinct mathematical approaches for quantifying NO-dependent vasodilation.
• To determine how different quantification methods impact the interpretation and reproducibility of NO-dependent skin vasodilation data.

Main Methods:

• Retrospective analysis of cutaneous vascular conductance (CVC) data from human participants undergoing LH.
• Application of four calculation methods: absolute NO-dependent component, difference in %CVCmax (Δ%CVCmax), percentage of LH plateau ( %plateau), and baseline-corrected %plateau (%plateauBL).
• Comparison of NO-dependent vasodilation responses between LH at 39°C and 42°C, with and without NO synthase inhibition (l-NAME).

Main Results:

• Higher absolute contributions of non-NO-dependent and NO-dependent components, and greater Δ%CVCmax, were observed at 42°C compared to 39°C (P ≤ 0.02).
• No significant differences were found between the 39°C and 42°C protocols for %plateau (P = 0.57) or %plateauBL (P = 0.31).
• All quantification methods showed significant differences when compared to each other (%plateauBL > %plateau > Δ%CVCmax; P ≤ 0.05), indicating method-dependent outcomes.

Conclusions:

• The quantification and description of NO-dependent skin vasodilation responses to LH are significantly influenced by the chosen mathematical approach.
• Discrepancies in calculated NO-dependent dilation responses highlight the potential for meaningful impacts on data interpretation and reproducibility.
• Researchers must carefully consider and report the specific methods used for quantifying NO-dependent vasodilation to ensure clarity and consistency in microvascular research.