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Updated: Jul 15, 2026
A Methodological Approach to Non-invasive Assessments of Vascular Function and Morphology
Published on: February 7, 2015
Noninvasive measure of microvascular nitric oxide function in humans using very low-frequency cutaneous laser Doppler
Julian M Stewart1, Indu Taneja, Michael S Goligorsky
1New York Medical College, Valhalla, New York, USA. stewart@nymc.edu
Objective:
While higher frequency oscillations (0.021-0.6 Hz) in cutaneous blood flow measured by laser Doppler flowmetry (LDF) relate to oscillations in blood pressure and sympathetic nerve activity, very low-frequency oscillations (VLF, 0.0095-0.021 Hz) do not. The authors investigated whether VLF LDF power is nitric oxide (NO) specific.
Methods:
LDF combined with intradermal microdialysis was used in the calves of 22 healthy volunteers aged 19-27 years. LDF power spectral analysis was performed by windowed fast Fourier transform. The authors tested whether the NO synthesis inhibitor nitro-l-arginine (NLA) produced selective decreases in VLF power before and after stimulation with acetylcholine.
Results:
NLA alone did not alter total power but selectively reduced VLF power by approximately 50%. LDF and spectral power increased markedly across all spectra with acetylcholine. This increase was blunted by NLA, which selectively reduced VLF power by approximately 50%.
Conclusions:
The data suggest that VLF oscillations in the laser Doppler signal are NO dependent, increase with cholinergic stimulation, and have potential as a noninvasive marker for NO-dependent microvascular reactivity.
