Изменение кожного кровотока при НIFU-индуцируемой дегрануляции тучных клеток

Abstract

Introduction. One of the promising methods of treating oncological diseases is high-frequency focused ultrasound (HIFU). The high-frequency acoustic field generated by the emitters induces mechanothermal effects whose significance has not yet been fully assessed and their study will change the tactics of therapy. To analyze their role, we selected cellular perivascular regulators of local blood flow – mast cells (MCs). Changes in the microcirculation (MCT) allow us to judge the morphofunctional state of the MC. The aim of the study is to assess the state of the rat’s skin periphocal tissue blood flow and MCs morphofunctional properties after HIFU-exposure. Material and methods. Adult male Wistar rats were used. Animals were divided into 3 groups: control, non-contact local heating of the skin and HIFU-induced exposure. For HIFU, an experimental setting was used, consisting of a concave emitter H-148 S / N 010 with a central oscillation frequency of 1.4 MHz. In the averaged interference spot, the radiation intensity was 8.2 kW/cm2. The exposure duration from 150 to 700 ms. Depth of focus is about 1 mm. To assess the MCT, a laser doppler flowmeter was used. Material for the manufacture of film preparations of MCs was taken at the site of exposure and according to the standard method. MCs calculation was carried out using the software «Multimedia Catalog» taking into account their morphofunctional characteristics. Results. HIFU exposure led to a significant increase in blood flow in rat’s skin at an exposure time of 250 ms or more (p<0.01). The maximum increase in perfusion was noted at 400 ms. The highest increase in tissue blood flow with local heating was observed at 45°C (p<0.001). HIFU-exposure led to a significant decrease in the density of MCs in the subcutaneous fat tissue of rat’s skin compared with the control at an exposure time of 250 ms or more (p<0.05) and a significant decrease in the relative number of type I cells, and an increase in type II and III, which indicates degranulation (p<0.05). Similar changes in the amount and morphofunctional characteristics of MCs were observed in a series of experiments with local heating, but the changes were not so significant. Conclusions. With HIFU-induced exposure, increased MCT in the peripheral zones is observed, accompanied by processes of morphofunctional rearrangement of the MCs, which indicates a combined mechanothermal disturbance in the focus zone, which forms the spatiotemporal continuum of the thermal field.