The purpose of the present study was to investigate the use of laser Doppler flowmetry (LDF) signals coupled with spectral wavelet analysis to detect endothelial link dysfunction in the autoregulation of cerebral blood flow in the setting of hyperhomocysteinaemia (HHcy). Fifty-one rats were assigned to three groups (intact, control, and HHcy) according to the results of biochemical assays of homocysteine level in blood plasma. LDF signals on the rat brain were recorded by LAKK-02 device to measure the microcirculatory blood flow. The laser operating wavelength and output power density were1064 nm and 0.051 W/mm2, respectively. A Morlet mother wavelet transform was applied to the measured 8-min LDF signals, and periodic oscillations with five frequency intervals were identified (0.01–0.04 Hz, 0.04–0.15 Hz, 0.15–0.4 Hz, 0.4–2 Hz, and 2–5 Hz) corresponding to endothelial, neurogenic, myogenic, respiratory, and cardiac origins, respectively. In initial state, the amplitude of the oscillations decreased by 38% (P < 0.05) in the endothelial range in HHcy rats than in control rats. Cerebral autoregulation was challenged by hemorrhagic hypotension. The lower limit of autoregulation raised in a rat model of chronic HHcy (71.5 ± 0.7 mmHg in HHcy vs. 62.3 ± 0.5 mmHg in control). The data obtained indicate that the laser Doppler method and wavelet analysis may be successfully applied to detect the dysfunction of the endothelial link in cerebral vessel tone and to reveal the pathological shift of lower limit of autoregulation.
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The Russian Science Foundation (Grant Number 16-15-10340) is acknowledged for their financial support of this study.
Compliance with ethical standards
All experimental procedures involving animals were performed in accordance with the ethical standards of the institutional ethical committee (protocol N4 of 04.07.2017) and the EU Directive 2010/63/EU on the protection of animals used for scientific purposes adopted on September 22, 2010, and the Rules of Laboratory Practice in the Russian Federation (Order of the Ministry of Health Care of the Russian Federation No. 199 n of 01.04.2016).
Conflict of interest
The authors declare that they have no conflict of interest.
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