ANALYSIS OF LDF-GRAMS IN WISTAR RUNOFF RATS UNDER HYPOXIA MODELING CONDITIONS
Authors: Alistratova F. I. , Toropova Ya. G. , Osipova S. A. , Vasyutina M. L. 
Published: July 2021

The aim of the study was to assess the dynamics of the change in peripheral blood flow parameters of the blood vessels of the microcirculatory bed of the skin, with an additional analysis of the change in the amplitude of the frequency ranges of cutaneous blood flow, in the conditions of daily interval hypobaric training by laser Doppler flowmetry.
The effect of interval hypobaric training course (seven days duration, exposure duration was 60 minutes) on the state of the microcirculatory bed of the skin was investigated to study the peculiarities of the formation and course of adaptive reactions in the vessels of the microcircuit.
An analysis of microcirculation indicators using LDF diagnostics was carried out. Hardware – laser analyzer of capillary circulation «LACC-02» manufactured by LLC NPP «Lasma,» Moscow. The main basal blood flow indicators and microcirculation indicators were revealed when exposed to a 7-day course of interval hypobaric training. The statistical values of PM (constant perfusion parameter, units), σ (mean square deviation of amplitude of perfusion fluctuation, units) and Kv (coefficient of variation, %) provided an opportunity to analyze the general state of blood microcirculation. The amplitude-frequency spectrum of perfusion oscillations was also evaluated. With the help of a wavelet analysis (program 2.2.0.507, NPP Lasma, Russia), normalized amplitudes of blood flow fluctuations in frequency ranges were determined (endothelial due to nitric oxide activity (0.0095–0.02 Hz); neurogenic (0.02–0.06 Hz); myogenic (vasomosis) (0.06–0.2 Hz) and passive frequency range (cardiac (0.6–1.6 Hz), respiratory (0.2–0.6 Hz). Measurement of microcirculation parameters was carried out 3 times at the following stages of the experiment: before hypoxic exposure – point 0 (8 minutes), on the 1st day immediately after hypoxia exposure (8 minutes), and on the 7th day immediately after hypoxia session (8 minutes). The measurement area was the inner surface of the lower pelvic limb, the LDF sensor was located on the surface of the skin. The recording duration was 360 seconds.
The hypoxic effect used in the study was implemented using hardware – an experimental hypobarocamera, in which the necessary conditions were created (negative pressure (–0.306kg/cm2)). The pressure in the chamber was reduced in stages: the first stage – a height of 1000 m with air dilution (–0.1 kg/cm2), duration 180 seconds; second stage – 2000 m rarefaction was (–0.21 kg/cm2) with the same duration; and the last stage is 3000 m high, which corresponds to a vacuum (–0.306 kg/cm2).
A seven-day course of hypoxia did not cause significant changes in cutaneous blood flow in animals in group C (control), and in animals in group P (pseudo-hypoxic rats). However, it was found that in rats in group H (hypoxia) there was an increase in the coefficient of variation by 62.5 % (p≤ 0.05) on the 7th day of exposure, this may be due to the launch of adaptation mechanisms, which are necessary to adequately supply blood to cells, tissues and organs. When analyzing LDF-grams in rats of group C (control) and P (pseudo-hypoxed), there was no change in the perfusion parameter in the microcirculatory channel, but in group G (hypoxia) – PM (microcirculation index) significantly decreased by 47 % (p<0.05). In animals of groups C (control) and P (psvedo-hypoxed), there were no significant changes, according to the data of the wavelet analysis. However, in group H rats (hypoxia) on the 1st day of exposure, there was an increase in the frequency of the amplitude of oscillations in the myogenic range (0.06–0.2 Hz) on 18.72 % (p < 0.05) and passive frequency ranges (cardiac modulating factor (0.6–1.6 Hz) in the LDF-gram of the subjects on 14.97 % (p<0.05).
Summing up the above, the results of the analysis of LDF-grams and the microcirculation index (PM) made it possible to establish a significant role in the possible use of the LDF-diagnostic method to evaluate the quality of methods for increasing the adaptive capabilities of the vessels of the skin microcirculatory bed and also central vessels. The dynamics of the frequency ranges of the vessels of nutritive blood flow in rats after a weekly course of interval hypobaric changed as follows: the role of passive factors, mainly the pulse wave from the arterial link, was increased by 24 % (p<0.05). The observed changes can be related to the enhancement of muscle cells in the vascular wall of the arterial vessels of the skin microcirculatory system, and as a result, the enhancement of the functioning of the circulatory system.
By laser Doppler flowmetry, the dynamics of changes in peripheral circulatory indices were investigated with the assessment of changes in rats, with the study of the frequency ranges of cutaneous blood.