The electrochemical properties of N-methyl- and N-phenyl-2,4,6-triphenylpyridinium perchlorates were studied by cyclic voltammetry (CV). The substituent at the nitrogen atom strongly affects the ...potentials of salt reduction and the electrochemical reversibility of the transfer of the second electron.
The ratio of low-frequency (LF, ~0.1 Hz) waves of RR interval duration (RRI) and systolic blood pressure (SAP) reflects the cardiac baroreflex sensitivity (BRS). Gravitational unloading (GU) may ...alter BRS during head-up tilt test (HUT) and lower body negative pressure (LBNP) test. Both effects cause blood redistribution to the lower body, but HUT is accompanied by greater unloading of sinocarotid baroreceptors than LBNP and activation of the vestibulosympathetic reflex. However, GU effects on BRS in these tests have not been directly compared previously. In this study we tested the hypothesis that the effect of dry immersion (DI, on-ground model of GU) on BRS in the same subjects will be more pronounced during HUT than during LBNP, while causing a comparable decrease in stroke volume (SV). Nine healthy men participated in two test sessions (before and after 7-day DI) consisting of five 3-min HUT (65°C) and five 3-min LBNP (–35 mmHg) with data averaging in each test. Wavelet analysis was used to determine the amplitude of the RRI and SAP waves in the 0.05–0.13 Hz range. The amplitude of LF waves of SAP increased in both tests, after DI—more significantly in HUT. The amplitude of LF RRI waves decreased in two tests; the percentage decrease did not differ between tests and did not change under the influence of DI. The α-coefficient (the ratio of RRI and SAP LF wave amplitudes) decreased equally in two tests before DI. After DI, more pronounced α-coefficient reduction was observed in HUT test but not in LBNP test. Thus, the effect of DI on BRS is evident in HUT, but not in LBNP, which may be explained by the more pronounced influence of HUT on the mechanisms of neural control of heart rhythm.
Absrtact. Prospects for the Chukotka's economic development are associated with several aspects: trends of the Northern Sea Route and its infrastructure revival; renewal of the peninsula energy ...system; the presence of profitable resource projects for the extraction of, copper, coal, oil and gas, and the need to develop the defence infrastructure on the northeast border of Russia. At the same time, extremely uncomfortable conditions for living and doing business, poor development of transport and social infrastructure, state of the energy system, shortage of skilled labor, environmental restrictions make economic indicators of projects unsatisfactory. Under these conditions, traditional project analysis should be transformed into the analysis of value chains, i.e. bundles of investment projects should be considered simultaneously. The purpose of this work was to understand the possible spatial organization of the Chukotka's economy and economic -mathematical modelling of interrelated perspective projects within the projected centres of economic development. Systematization of data on promising projects of the Chukotka Autonomous District allowed defining the contours of three promising ATPCs - Peveksky, Anadyrsky and Lorinsky. Further, using the author's simulation model, forecasted effects of four technologically related projects were assessed: the copper deposit Peschanka, the gold deposit Kekura, the floating nuclear power plant and the Pevek sea port. The toolkit created by the authors can be used to justify the development priorities of the Chukotka Autonomous District, as well as to assess the various institutional conditions for the implementation of investment projects in the region.
We studied the effects of long-term anti-orthostatic hypokinesia (head-down bed rest—BR, a model of gravitational unloading) on the dynamics of orthostasis-induced changes in the content of total ...(THb), deoxygenated (HHb), and oxygenated (OHb) hemoglobin in the calf at the level of the gastrocnemius muscle medial head using near-infrared spectroscopy. In seven young men, 2–4 days before and on the 19th day of BR, a passive head-up tilt test was performed (15 min in the supine position, then 15 min at 65°). After BR, there was an increase in heart rate and a decrease in stroke volume in the supine position, as well as more pronounced changes in these parameters during orthostasis. Blood pressure in the supine position and orthostasis did not change after BR. THb content increased gradually during orthostasis and reached a plateau by the end of the test; after BR, an increase in the half-rise time and a twofold increase in the plateau level were observed. Tissue HHb content by the end of the tilt test also increased after BR. The dynamics of OHb before BR was more complicated: this indicator grew, reached a maximum during a minute, and then gradually decreased to half of the maximum by the end of the test. After BR, the dynamics of OHb changed drastically: the signal increased gradually and reached a level that was twice the peak value of OHb content before BR. The results allow us to conclude that exposure to BR weakens the compensatory constriction of calf vessels during tilt test; consequently, it is followed by higher blood accumulation in calf vascular bed, which, in turn, leads to smaller SV during orthostasis.
The change in the diameter of small arteries and arterioles is a key mechanism for regulating the resistance of the vascular bed and blood pressure and blood flow in organs and tissues. The tone of ...arterial smooth muscle cells (SMC) depends on the level of membrane potential (MP), which, in turn, is determined by the balance of depolarizing and hyperpolarizing currents. The main hyperpolarizing current of SMC is the outward potassium current. Activation and opening of potassium channels counteract depolarization and inhibit calcium entry into the cell and contraction. Thus, potassium channels play an anticonstrictor role in the arteries. TASK-1 channels, members of the two-pore domain potassium channel family (K
2P
), have relatively recently been described in the vasculature. It is known that TASK-1 channels mediate outward potassium leakage current in arterial SMC. In addition, TASK-1 channels are regulated by a number of stimuli: their activity augments with an increase of extracellular pH, decreases in hypoxia, and can also change under the influence of inhalation/local anesthetics and vasoactive substances. TASK-1 channels play an important role in the regulation of arterial tone in pulmonary circulation; their dysfunction is one of the causes of arterial pulmonary hypertension development. In systemic arteries of adult animals, the influence of TASK-1 channels under normal pH is small or absent, but it can manifest itself under conditions of extracellular alkalosis. In addition, the anticontractile role of TASK-1 channels is more pronounced at the early stages of postnatal development. This review outlines the current understanding of the functional role and regulation of TASK-1 channels in the vascular system.
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The nongenomic effects of thyroid hormones (THs) develop within minutes or hours and do not depend on the binding of the hormone to the transcriptionally active nuclear receptors TRα and TRβ. These ...effects are characterized by a variety of receptors and signaling pathways involved, which may be distinct in different cell types. Thyroxin (T
3
) or triiodthyronine (T
4
) can induce a nongenomic effect by association with transcriptionally inactive TRα and TRβ in the cell cytoplasm, their truncated isoforms, or αvβ3 integrin. With nongenomic action, as well as with genomic action, T
3
and T
4
can alter gene transcription, but their influence is extended to a wider spectrum of genes in this case. The nongenomic effects of THs often complement the genomic ones, causing similar changes in cell activity, or enhance them by providing TRα and TRβ translocation into the nucleus or their posttranslational modification. The nongenomic effects of THs on the vasculature include angiogenesis and rapid vasodilation. The key signaling cascade mediating angiogenesis includes αvβ3 integrin, protein kinase D, and histone deacetylase 5. The mechanisms of rapid vasodilation are still poorly understood and may vary in different regions of the vascular bed. In cytoplasm of endothelial cells, the nongenomic effect of THs is mediated by TRα1, PI3K, and NO synthase, although this mechanism is not universal. TH-induced vasodilation of skeletal muscle arteries includes the participation of αvβ3 integrin located in smooth muscle cells, but the signaling cascades triggered by it have not yet been studied. Knowledge of the molecular mechanisms of the nongenomic effect of thyroid hormones is important for the development of new methods of pharmacological correction of vascular pathologies, which are usually associated with thyroid disorders.
During early post-natal development, arterial contraction depends less on Ca
-signalling pathways but more on changes in Ca
-sensitivity compared to adult animals. Whether this difference is related ...to Rho-kinase, one of the major players affecting Ca
-sensitivity, is unknown for intact vessels. Thus, we tested the hypothesis that Rho-kinase critically contributes to the higher Ca
-sensitivity of contraction in intact arteries of 1-week-old rats.
We studied 1-week-old, 4- to 5-week-old and 10- to 12-week-old rats performing isometric myography, Ca
-fluorimetry and Western blotting using intact saphenous arteries and arterial pressure measurements under urethane anaesthesia.
In 10- to 12-week-old rats, methoxamine (MX) produced vasoconstriction associated with an increase in Ca
and Ca
-sensitivity. In contrast, in 1-week-old rats these contractions were accompanied only by an increase in Ca
-sensitivity. All MX-induced effects were reduced by the Rho-kinase inhibitor Y-27632; this reduction was complete only in 1-week-old rats. The Rho-kinase specific site Thr
on MYPT1 was increasingly phosphorylated by MX in vessels of 1-week-old, but not 10- to 12-week-old rats; this effect was also inhibited completely by Y-27632. The Rho-kinase inhibitor fasudil in a dose not affecting the pressor response to MX in 4- to 5-week-old rats reduced it considerably in 1-week-old rats.
Our results suggest that the higher Ca
-sensitivity of arterial contraction in 1-week-old compared to 10- to 12-week-old rats is due to a greater Rho-kinase activity. Constitutively active Rho-kinase contributes to MX-induced contraction in 10- to 12-week-old rats. In 1-week-old rats, additional Rho-kinase activation is involved. This remodelling of the Rho-kinase pathway is associated with its increased contribution to adrenergic arterial pressure responses.
Successive one-pot reactions of monolithiated
N
,
N
-diethylprop-2-yn-1-amine with 2-(ethenyloxy)ethyl isothiocyanate and 2-(bromomethyl)-1,3-dioxolane afforded ...5-(1,3-dioxolan-2-ylmethyl)sulfanyl-12-(ethenyloxy)ethyl-
N
,
N
-diethyl-1
H
-pyrrol-2-amine in 91% yield. In the system
t
-BuOK–DMSO at room temperature (1 h), the product was converted to 1-2-(ethenyloxy)ethyl-
N
,
N
-diethyl-5-{2-(2-hydroxyethoxy)ethenylsulfanyl}-1
H
-pyrrol-2-amine (yield 68%) instead of expected 1-vinyl derivative.
The possibility of the coupled electrochemical reduction of carbon dioxide and hydrogen in the presence of 2,2'-bipyridine and its
N
-substituted salts in the presence of acids with different p
K
a ...values was studied. It was found that the strength of the acid affects the efficiency of the process; in particular, methylsulfonic acid promotes the coupled hydrogen formation and the reduction of carbon dioxide to formic acid. Plausible mechanisms of the reactions that occurred have been proposed.
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