Mitochondria from rat uterine smooth muscle possess ATP-sensitive potassium channel

AbstractThe objective of this study was to detect ATP-sensitive K+ uptake in rat uterine smooth muscle mitochondria and to determine possible effects of its activation on mitochondrial physiology. By means of fluorescent technique with usage of K+-sensitive fluorescent probe PBFI (potassium-binding benzofuran isophthalate) we showed that accumulation of K ions in isolated mitochondria from rat myometrium is sensitive to effectors of KATP-channel (ATP-sensitive K+-channel) – ATP, diazoxide, glibenclamide and 5HD (5-hydroxydecanoate). Our data demonstrates that K+ uptake in isolated myometrium mitochondria results in a slight decrease in membrane potential, enhancement of generation of ROS (reactive oxygen species) and mitochondrial swelling. Particularly, the addition of ATP into incubation medium led to a decrease in mitochondrial swelling and ROS production, and an increase in membrane potential. These effects were eliminated by diazoxide. If blockers of KATP-channel were added along with diazoxide, the effects of diazoxide were removed. So, we postulate the existence of KATP-channels in rat uterus mitochondria and assume that their functioning may regulate physiological conditions of mitochondria, such as matrix volume, ROS generation and polarization of mitochondrial membrane

ПОШИРЕНІСТЬ ФАКТОРІВ РИЗИКУ ОНКОПАТОЛОГІЇ РОТОВОЇ ПОРОЖНИНИ В ОСІБ ШКІЛЬНОГО ВІКУ З РІЗНИМ РІВНЕМ ТРИВОЖНОСТІ

It was studied the condition of periodont of children of middle and high school age with different level of anxiety. We revealed a significant prevalence of its destruction since 11–12 years. Also there was indicated that child’s anxiety affects the condition of periodontal soft tissues. Chronic catarrhal gingivitis authentically more often was observed in children with high anxiety in comparison with schoolchildren with low anxiety. It is recommended to carry out oncological reviews of the oral cavity since middle school age children. Проанализировано состояние пародонта у детей среднего и старшего школьного возраста с разным уровнем тревожности. Установлено, что психоэмоциональное состояние ребенка влияет на мягкие ткани пародонта. У детей с высокой тревожностью, особенно в возрасте 14–17 лет, достоверно чаще определялась средняя степень хронического катарального гингивита и РМА индекса по сравнению с учениками с низкой тревожностью. Уровень тревожности достоверно не влиял на состояние гигиены полости рта у детей обеих возрастных групп. Оцінено стан пародонта у дітей середнього та старшого шкільного віку з різним рівнем тривожності. Виявлено значну розповсюдженість його уражень, починаючи з 11–12 років, також показано, що тривожність дитини впливає на стан м’яких тканин пародонта. У дітей із високою тривожністю, достовірно частіше відмічався хронічний катаральний гінгівіт порівняно з учнями з низькою тривожністю. Рекомендується проводити онкоогляди ротової порожнини, починаючи з дітей старшого шкільного віку.

ATP-sensitive K(+)-channels in muscle cells: features and physiological role

ATP-sensitive K+-channels of plasma membranes belong to the inward rectifier potassium channels type. They are involved in coupling of electrical activity of muscle cell with its metabolic­ state. These channels are heterooctameric and consist of two types of subunits: four poreforming (Kir 6.х) and four regulatory (SUR, sulfonylurea receptor). The Kir subunits contain highly selective K+ filter and provide for high-velocity K+ currents. The SUR subunits contain binding sites for activators and blockers and have metabolic sensor, which enables channel activation under conditions of metabolic stress. ATP blocks K+ currents through the ATP-sensitive K+-channels in the most types of muscle cells. However, functional activity of these channels does not depend on absolute concentration of ATP but on the АТР/ADP ratio and presence of Mg2+. Physiologically active substances, such as phosphatidylinositol bisphosphate and fatty acid esters can regulate the activity of these structures in muscle cells. Activation of these channels under ischemic conditions underlies their cytoprotective action, which results in prevention of Ca2+ overload in cytosol. In contrast to ATP-sensitive K+-channels of plasma membranes, the data regarding the structure and function of ATP-sensitive K+-channels of mitochondrial membrane are contradictory. Pore-forming subunits of this channel have not been firmly identified yet. ATP-sensitive K+ transport through the mitochondrial­ membrane is easily tested by different methods, which are briefly reviewed in this paper. Interaction of mitoKATP with physiological and pharmacological ligands is discussed as well

Involvement of KАТР-channels of plasma and mitochondrial membranes in maintaining the contractive function of myometrium of non-pregnant rat uterus

K+-channels, in particular, ATP-sensitive K+-channels of plasma and inner mitochondrial membranes, play a significant role in regulating the contraction-relaxation processes in visceral smooth muscles. The specificities of these channels and their role in maintaining excitation have been well investigated for the cardiac muscle and smooth vascular muscles. However, scarce data exist about the involvement of these channels, especially the mitochondrial ones, in regulating myometrium contractions. The tenzometric methods and mechanokinetic analysis were used to study the regularities in oxytocin-induced contractions of smooth muscles of non-pregnant rats myometrium under the conditions of modulating ATP-sensitive K+-channels of plasma and inner mitochondrial membranes. It was determined that prior incubation of myometrium in the presence of the blocking agents of KATP-channels of plasma membrane and mitochondria (glibenclamide and 5-hydroxydecanoate, respectively) was generally associated with the increase in the phase and, in some cases, tonic components of oxytocin-induced contractions. There was an increase in the amplitude of oxytocin-induced contractions at the background of the impact of glibenclamide (the range of concentrations used was 1–10 µM) without significant changes in the area under these mechanograms; the velo­city of relaxation increased considerably as well. The blocking agent of mitochondrial ATP-sensitive K+-channels, 5-hydroxydecanoate (in the concentrations of 50 µM and 200 µM) caused considerable changes in the kinetics of the processes of intensification (the increase in velocity) and decline (more than 2-fold decrease in the velocity) in comparison with the force of oxytocin-induced contractions, but it did not impact their amplitude and the area under mechanograms. The most significant effect, demonstrated by the activator of ATP-sensitive K+-channels of diazoxide (the range of concentrations was 50–200 µM), was the reduction in the area under oxytocin-induced contractions by half. This compound also caused a decrease in the amplitude of contractions and a considerable increase in the maximal velocities of the intensification and decline phases for the force of oxytocin-induced contractions. The combined effect of the blo­cking agents of KATP-channels of plasma and inner mitochondrial membranes, glibenclamide (10 µM) and 5-hydroxydecanoate (200 µM), was accompanied by the increase in the amplitude of oxytocin-induced contractions and the changes in the kinetics of contraction and relaxation processes. Thus, the data obtained demonstrate that KATP-channels of plasma membrane and mitoKATP-channels in non-pregnant rats’ myome­trium play a modulating role in forming the contractive response to the uterotonic hormone oxytocin. These channels are involved in the regulation of the contractive function of myometrium, modulating the amplitude of contractions, the ability of long-term strain support and the kinetics of contraction and relaxation processes

Mitochondria from rat uterine smooth muscle possess ATP-sensitive potassium channel

The objective of this study was to detect ATP-sensitive K+ uptake in rat uterine smooth muscle mitochondria and to determine possible effects of its activation on mitochondrial physiology. By means of fluorescent technique with usage of K+-sensitive fluorescent probe PBFI (potassium-binding benzofuran isophthalate) we showed that accumulation of K ions in isolated mitochondria from rat myometrium is sensitive to effectors of KATP-channel (ATP-sensitive K+-channel) – ATP, diazoxide, glibenclamide and 5HD (5-hydroxydecanoate). Our data demonstrates that K+ uptake in isolated myometrium mitochondria results in a slight decrease in membrane potential, enhancement of generation of ROS (reactive oxygen species) and mitochondrial swelling. Particularly, the addition of ATP into incubation medium led to a decrease in mitochondrial swelling and ROS production, and an increase in membrane potential. These effects were eliminated by diazoxide. If blockers of KATP-channel were added along with diazoxide, the effects of diazoxide were removed. So, we postulate the existence of KATP-channels in rat uterus mitochondria and assume that their functioning may regulate physiological conditions of mitochondria, such as matrix volume, ROS generation and polarization of mitochondrial membrane. Keywords: ATP-sensitive potassium channel, Diazoxide, 5-hydroxydecanoate, Myometrium, Mitochondria, Mitochondrial swelling, Mitochondrial membrane potential, RO

Non-peptide furin inhibitors based on amidinohydrazones of diarylaldehydes

A series of novel non-peptidic furin inhibitors containing amidinohydrazone moieties has been synthesized under interaction of dialdehydes, the derivatives of ethylene diethylvanillin ethers, with aminoguanidine bicarbonate. Two aryl cycles were bridged by 1,2-ethylene-, 1,4-buthylene- or 1,4-dimethylenebenzene-group. The compounds have been found to inhibit furin. The antifurin activity was shown to grow with the increase of the length and/or hydrophobicity of the bridge. The most potent compound, containing in the bridge the lypophylic benzene cycle was found to inhibit the activity of furin with Ki = 0.51 µM

In Vitro Evaluation of In Silico Screening Approaches in Search for Selective ACE2 Binding Chemical Probes

New models for ACE2 receptor binding, based on QSAR and docking algorithms were developed, using XRD structural data and ChEMBL 26 database hits as training sets. The selectivity of the potential ACE2-binding ligands towards Neprilysin (NEP) and ACE was evaluated. The Enamine screening collection (3.2 million compounds) was virtually screened according to the above models, in order to find possible ACE2-chemical probes, useful for the study of SARS-CoV2-induced neurological disorders. An enzymology inhibition assay for ACE2 was optimized, and the combined diversified set of predicted selective ACE2-binding molecules from QSAR modeling, docking, and ultrafast docking was screened in vitro. The in vitro hits included two novel chemotypes suitable for further optimization