Volume 109, Nº 3 (2023)

The actin cytoskeleton is involved in the regulation of the barrier function of the endothelium. The bioavailability of arginine is an important factor determining of actin cytoskeleton dynamics. Pathogenic microorganisms can use arginine-hydrolyzing enzymes to disrupt the confluences of the vascular endothelium for subsequent dissemination. In this study, the effect of streptococcal arginine deiminase on the human umbilical vein endothelial cells monolayer confluence and the actin cytoskeleton structure in vitro was studied. The original technique for obtaining supernatants by sonication destroyed streptococcal cells (SDSCs) of the original strain of Streptococcus pyogenes M49-16 and its isogenic mutant with the inactivated arginine deiminase gene S. pyogenes M49-16delArcA was used in this study. The changes in the L-arginine concentration were evaluated by the modified Sakaguchi colorimetric method. The structure of the actin cytoskeleton was analyzed after cells staining with fluorescent dye labeled phalloidin. The confluence of the endothelial cell monolayer was evaluated morphologically after staining the cells with crystal violet dye. It was found that in the presence of the parental strain-derived SDSC, a significant decrease in the arginine concentration in the endothelial cells culture medium caused dynamic changes in the actin cytoskeleton structure. After 48 hours, lamellae and stress fibers formed. After 72 hours, the content of F-actin decreased and the confluence of the monolayer of endothelial cells was disrupted. Such changes were not detected when cells were cultured under standard conditions and in the presence of mutant strain-derived SDSC. The results obtained show that pathogenic microbes can use arginine depletion to regulate endothelial barrier function and dissemination in the host organism.

The purpose of the research was to study the contribution of the superoxide radical (\({\text{O}}_{2}^{{\centerdot - }}\)) to the mechanisms of the coronary K_V-channels functional activity impairment in rats with posttraumatic stress disorder (PTSD). The study was performed on 117 outbred white male rats (Rattus, Muridae weighing 210–240 g). To reproduce the experimental analogue of PTSD, the modified model of “a predator presence imitation” was applied (contact with cats’ excrements for 10 days, 15 minutes daily). The PTSD development was confirmed by behavioral changes of affected animals in the “Open Field” test. The coronary vessels’ tone was studied on the isolated by the Langendorf’s method isotonically contracted hearts, which were perfused under constant flow with Krebs–Henseleit solution. The contribution of \({\text{O}}_{2}^{{\centerdot - }}\) to the coronary vascular tone regulation was studied by infusion of the superoxide radical “scavenger” Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid) in the perfusion solution. The functional activity of K_V-channels was assessed by the degree of increase in the coronary perfusion pressure (CPP) in response to 4-aminopyridine (4-AP), a blocker of K_V-channels. To elucidate the role of \({\text{O}}_{2}^{{\centerdot - }}\) in the K_V‑channels functional activity of coronary vessels, Tiron and 4-AP were infused in the perfusion solution. The concentration of diene conjugates (DCs), malondialdehyde (MDA), C‑reactive protein (C-RP) and interleukin 1β (IL-1β) as well as catalase (CAT) and superoxide dismutase (SOD) activity were detected in the blood serum of experimental animals. The CPP in the isolated rats’ hearts after PTSD was 30% lower at coronary flow rate 10 mL/min compared to the control group. Under the influence of 4-AP, CPP increased by 70% and by 24% in the “Control” and “PTSD” groups, respectively. Under influence of Tiron, the CPP in the “PTSD” group at coronary flow rate 10 mL/min was 52% lower than in the control. In the “PTSD + Tiron + 4-AP” group the CPP augmentation (71.5%) was comparable to that in the hearts of the “Control” group after 4-AP exposure. The IL-1β, C-RP, DCs and MDA concentration in the blood serum of rats with PTSD was 3, 1.6, 3.3 and 3.6 times higher than in the control rats’ blood serum, while SOD and CAT activity was by 27 and 59% lower, compared to control, respectively. In the course of the investigation, it was found that \({\text{O}}_{2}^{{\centerdot - }}\) overproduction due to oxidative stress might be an important mechanism of a poststressor “channelopathy”, which is characterized by the decreased functional activity of the K_V-channels of coronary vessels following PTSD.

Glucose is widely used as an osmotic agent in the preparation of solutions for peritoneal dialysis. The aim of this work was to study the effect of glucose on the expression of the water channel aquaporin- 1 (AQP1) and the transcription factor TonEBP, as well as on water permeability of cells in the primary mesothelial mesentery culture of Wistar rats. The method of fluorescence microscopy with intracellular dye сalcein was used in the work. The mRNA content was evaluated by real time RT-PCR. Preincubation of cells in a DMEM medium containing glucose (2.3%, 24 hours, 37°C, 5% CO₂) led to a decrease in the expression of the aqp1 gene by approx. 60% (control 0.87 ± 0.18; glucose 0.34 ± 0.12, n = 9, p < 0.05) and tonebp by 20% (control 0.37 ± 0.024; glucose 0.3 ± 0.012, n = 9, p < 0.05). A decrease by 40% in the permeability to water of the plasma membrane of peritoneal mesothelium cells after 24 h preincubation with glucose was also observed (control 7.3Е–3 ± 1.3Е–3 (sm/s), n = 27; glucose 4.3E–3 ± ± 3.8E–4 (sm/s), n = 57, p < 0.01). The results of the study indicate that glucose can have an inhibitory effec-t on the transport processes in the cells of the peritoneal mesothelium, which, with multiple exposures, can lead to structural and functional disorders of the peritoneal membrane.

In this work, we studied the elemental composition of gonads, eggs, sperm and larvae of the mussel Mytilus galloprovincialis during spawning, when the contents of biologically active compounds and minerals are maximal. A comparative analysis of the contents showed that the elements are involved in the mussel gametogenesis in different pathways. There were significant differences in the contents of Li, B, Mg, Si, P, K, Ca, V, Cr, Mn, Fe, Co, Ni, Zn, Ge, As, Se, Br, Rb, Sr, Mo, Pd, Sn, I, Ba and Ce in male and female gonads before and after spawning, gametes and larvae of mussels. It is likely that some of the listed elements are not only passively accumulated in the mollusk body, but are also essential, being directly involved in the reproduction process. Most of significant differences in the element contents were found between eggs and larvae and between male gonads before spawning and sperm. By spawning, mussel gonads accumulated mainly p- and d-elements, apparently due to the ability of their ions to form complexes and, consequently, to be included in the structure of enzymes. The contents of B, Mg, Si, P, K, Ca, Cr, Mn, Fe, Cu, Zn, As, Se, Br, Sr and Ba in male and female gonads, gametes and larvae were an order or several orders of magnitude higher than those of other elements. The contents of Ca, Fe, Sr, Sn and I in mussel larvae were significantly higher than in gonads and gametes. Sn is a technological hydropollutant, and thus, larvae can serve as a bioindicator of the aquatic environment pollution with this element. The data obtained are of practical interest for improving the biotechnology of reproduction of marine hydrobionts and obtaining functional products based on them, which is important for the optimization of aquaculture management and for addressing human health-related issues.