Multivariate EEG spectral analysis evidences the functional link between motor and visual cortex during integrative sensorimotor tasks

The identification of the networks connecting brain areas and the understanding of their role in executing complex tasks is a crucial issue in cognitive neuroscience. In this study, specific visuomotor tasks were devised to reveal the functional network underlying the cooperation process between visual and motor regions. Electroencephalography (EEG) data were recorded from twelve healthy subjects during a combined visuomotor task, which integrated precise grip motor commands with sensory visual feedback (VM). This condition was compared with control tasks involving pure motor action (M), pure visual perception (V) and visuomotor performance without feedback (V + M). Multivariate parametric cross-spectral analysis was applied to ten EEG derivations in each subject to assess changes in the oscillatory activity of the involved cortical regions and quantify their coupling. Spectral decomposition was applied to precisely and objectively determine the power associated with each oscillatory component of the spectrum, while surrogate data analysis was performed to assess the statistical significance of estimated coherence values. A significant decrease of the alpha and/or beta power in EEG spectra with respect to rest values was assumed as indicative of specific cortical area activation during task execution. Indeed alpha band coherence increased in proximity of task-involved areas, while it was suppressed or remained unchanged in other regions, suggesting the activation of a specific network for each task. According to our coherence analysis, a direct link between visual and motor areas was activated during V + M and VM tasks. The effect of visual feedback was evident in the beta band, where the increase of coherence was observed only during the VM task. Multivariate analysis suggested the presence of a functional link between motor and visual cortex subserving sensorimotor integration. Furthermore, network activation was related to the sum of single task (M and V) local effects in the alpha band, and to the presence of visual feedback in the beta band.     

Selective spectrophotometric detection of insecticides using cholinesterases,phosphotriesterase and chemometric analysis

Enzyme spectrophotometric assays based on acetylcholinesterase (AChE) inhibition were used in combination with Artificial Neural Network (ANN) chemometric analysis for the resolution of pesticides mixtures of chlorpyriphos, dichlorvos and carbofuran. Electric eel (EE) AChE and the recombinant B394-AChE from Drosophila melanogaster were selected due to their different sensitivities to insecticides. These enzymes were used in association with phosphotriesterase (PTE), an enzyme allowing to discriminate between organophosphate and carbamate insecticides. The combined response of three enzymes systems composed of EE-AChE, EE-AChE + PTE, and B394-AChE + PTE was modelled by means of ANN. Specifically, an ANN was constructed where the structure providing the best modelling was a single hidden layer containing four neurons. To prove the concept, a study to resolve pesticide mixtures was done with spectrophotometric measurements. Finally the developed system was successfully applied to the determination of carbofuran, CPO and dichlorvos pesticides in real water samples.     

Intramedullary pressure and matrix strain induced by oscillatory skeletal muscle stimulation and its potential in adaptation

Intramedullary pressure (ImP) and low-level bone strain induced by oscillatory muscle stimulation (MS) has the potential to mitigate bone loss induced by disuse osteopenia, i.e., hindlimb suspension (HLS). To test this hypothesis, we evaluated (a) MS-induced ImP and bone strain as function of stimulation frequency and (b) the adaptive responses to functional disuse, and disuse plus 1 and 20 Hz stimulation in vivo. Femoral ImP and bone strain generated by MS were measured in the frequencies of 1–100 Hz in four rats. Forty retired breeder rats were used for the in vivo HLS study. The quadriceps muscle was stimulated at frequencies of 1 and 20 Hz, 10 min/d for four weeks. The metaphyseal trabecular bone quantity and microstructure at the distal femur were evaluated using μCT, while bone formation indices were analyzed using histomorphometric technique. Oscillatory MS generated a maximum ImP of 45±9 mmHg at 20 Hz and produced a maximum matrix strain of 128±19 με at 10 Hz. Our analyses from the in vivo study showed that MS at 20 Hz was able to attenuate trabecular bone loss and partially maintain the microstructure induced by HLS. Conversely, there was no evidence of an adaptive effect of stimulation at 1 Hz on disused skeleton. The results suggested that oscillatory MS regulates fluid dynamics and mechanical strain in bone, which serves as a critical mediator of adaptation. These results clearly demonstrated the ability of MS in attenuating bone loss from the disuse osteopenia, which may hold potential in mitigating skeletal degradation imposed by conditions of disuse, and may serve as a biomechanical intervention in clinic application.     

Endothelium oriented differentiation of bone marrow mesenchymal stem cells under chemical and mechanical stimulations

Bone marrow mesenchymal stem cells (MSCs) have multi-differentiation capability. Their endothelial cell (EC) oriented differentiation is the key to vasculogenesis, in which both mechanical and chemical stimulations play important roles. Most previous studies reported individual effects of VEGF or fluid shear stress (SS), when MSCs were subjected to shear stress of 10–15 dyn/cm² over 24 hr. In this paper, we investigated responses of MSCs from young Sprague Dawley rats to shear stress, VEGF and the combination of the two stimuli. Our study showed that the combined stimulation of shear stress and VEGF resulted in more profound EC oriented differentiation of MSCs in comparison to any individual stimulation. Furthermore, we subjected MSCs to prolonged period of fluid shear stimulation, i.e. 48 hr rather than 24 hr, and increased the magnitude of the shear stress from 10 dyn/cm² to 15, 20 and 25 dyn/cm². We found that without VEGF, the endothelium oriented differentiation of MSCs that was seen following 24 hr of shear stimulation was largely abolished if we extended the shear stimulation to 48 hr. A similar sharp decrease in MSC differentiation was also observed when the magnitude of the shear stress was increased from 10–15 dyn/cm² to 20–25 dyn/cm² in 24 hr shear stimulation studies. However, with combined VEGF and fluid shear stimulation, most of the endothelial differentiation was retained following an extended period, i.e. at 48 hr, of shear stimulation. Our study demonstrates that chemical and mechanical stimulations work together in determining MSC differentiation dynamics.     

Oscillatory fluid flow induces the osteogenic lineage commitment of mesenchymal stem cells: The effect of shear stress magnitude,frequency, and duration

A potent regulator of bone anabolism is physical loading. However, it is currently unclear whether physical stimuli such as fluid shear within the marrow cavity is sufficient to directly drive the osteogenic lineage commitment of resident mesenchymal stem cells (MSC). Therefore, the objective of the study is to employ a systematic analysis of oscillatory fluid flow (OFF) parameters predicted to occur in vivo on early MSC osteogenic responses and late stage lineage commitment. MSCs were exposed to OFF of 1 Pa, 2 Pa and 5 Pa magnitudes at frequencies of 0.5 Hz, 1 Hz and 2 Hz for 1 h, 2 h and 4 h of stimulation. Our findings demonstrate that OFF elicits a positive osteogenic response in MSCs in a shear stress magnitude, frequency, and duration dependent manner that is gene specific. Based on the mRNA expression of osteogenic markers Cox2, Runx2 and Opn after short-term fluid flow stimulation, we identified that a regime of 2 Pa shear magnitude and 2 Hz frequency induces the most robust and reliable upregulation in osteogenic gene expression. Furthermore, long-term mechanical stimulation utilising this regime, elicits a significant increase in collagen and mineral deposition when compared to static control demonstrating that mechanical stimuli predicted within the marrow is sufficient to directly drive osteogenesis.     

Modélisation des flux cérébraux par une analogie électrique : validation par vélocimétrie IRM

The cine Phase-Contrast Magnetic Resonance (PCMR) sequence is the only noninvasive technique for the study of cerebrospinal fluid (CSF) oscillations. It can provide CSF and blood flow measurements throughout the cardiac cycle. To study cerebral hydro-hemodynamic, models have been developed; nevertheless the majority of these models did not take into account the CSF oscillations. The objective of this study was to establish reference values for cerebral hydro-hemodynamic and propose a new electrical model of the brain dynamics.Material and methodsCSF and blood flows were measured in 19 control subjects by PCMR imaging. Dynamic flow images were analyzed on dedicated software to reconstruct the flow curves during the cardiac cycle. An electrical analogue was realized. The inputs of the model were fed by PCMR arterial and venous flows to simulate CSF oscillations. The simulated CSF oscillations were compared to the measured CSF oscillations to validate the model.ResultsThe key parameters of the CSF and blood flow curves were obtained, e.g. total cerebral blood flow was 688 ± 115 mL/min, ventricular CSF oscillatory volume was 0.05 ± 0.02 mL/cardiac cycle, and the subarachnoid CSF oscillatory volume was 0.55 ± 0.15 mL/cardiac cycle. A close agreement was found between measured and simulated cerebral CSF oscillations.ConclusionThis study established the main values characterizing cerebral hydrodynamics in a control population. It provided a better understanding of the mechanisms of intracranial volumes regulation during the cardiac cycle. Our results are now used in clinical practice and the model proposed is effective to study cerebral hydro-hemodynamic.     

Micro movements of the upper limb in fibromyalgia: The relation to proprioceptive accuracy and visual feedback

The purpose of this study was to explore the role of visual and proprioceptive feedback in upper limb posture control in fibromyalgia (FM) and to assess the coherence between acceleration measurements of upper limb micro movements and surface electromyography (sEMG) of shoulder muscle activity (upper trapezius and deltoid). Twenty-five female FM patients and 25 age- and sex-matched healthy controls (HCs) performed three precision motor tasks: (1) maintain a steady shoulder abduction angle of 45° while receiving visual feedback about upper arm position and supporting external loads (0.5, 1, or 2 kg), (2) maintain the same shoulder abduction angle without visual feedback (eyes closed) and no external loading, and (3) a joint position sense test (i.e., assessment of proprioceptive accuracy). Patients had more extensive increase in movement variance than HCs when visual feedback was removed (P < 0.03). Proprioceptive accuracy was related to movement variance in HCs (R ⩾ 0.59, P ⩽ 0.002), but not in patients (R ⩽ 0.25, P ⩾ 0.24). There was no difference between patients and HCs in coherence between sEMG and acceleration data. These results may indicate that FM patients are more dependent on visual feedback and less reliant on proprioceptive information for upper limb posture control compared to HCs.     

Cortical motor representation of the rectus femoris does not differ between the left and right hemisphere

Transcranial magnetic stimulation (TMS) involves non-invasive magnetic stimulation of the brain, and can be used to explore the corticomotor excitability and motor representations of skeletal muscles. However there is a lack of motor mapping studies in the lower limb and few conducted in healthy cohorts. The cortical motor representations of muscles can vary between individuals in terms of center position and area despite having a general localized region within the motor cortex. It is important to characterize the normal range for these variables in healthy cohorts to be able to evaluate changes in clinical populations. TMS was used in this cross-sectional study to assess the active motor threshold (AMT) and cortical representation area for rectus femoris in 15 healthy individuals (11 M/4F 27.3 ± 5.9 years). No differences were found between hemispheres (Left vs. Right P = 0.130) for AMT. In terms of y-axis center position no differences were found between hemispheres (Left vs. Right P = 0.539), or for the x-axis center position (Left vs. Right P = 0.076). Similarly, no differences in calculated area of the motor representation were found (Left vs. Right P = 0.699) indicating symmetry between hemispheres.     

High frequency body mass measurement,feedback, and health behaviors

We analyze weight and fat percentage measurements of respondents in an online general population panel in the Netherlands, collected using wireless scales, with an average frequency of 1.6 measurements per week. First, we document the existence of a weekly cycle; body mass is lowest on Fridays and highest on Mondays, showing significant (p < 0.01) differences of, on average, 0.2 kilogram in weight, 0.06 in BMI value, and 0.03 in fat percentage. Second, we find that in the general population fat-based measures of obesity point at a three times larger prevalence of obesity (53%) than BMI-based measures (17%). Third, we find that feedback that includes a recommended weight range increases the temporal variation in individual body mass by almost ten percent (sd for weight increases from 1.13 to 1.22; sd for BMI increases from 0.37 to 0.41; sd for fat percentage increases from 0.55 to 0.61.     

Oligomerization–function relationship of EGFR on living cells detected by the coiled-coil labeling and FRET microscopy

The epidermal growth factor receptor (EGFR) is a well-studied receptor tyrosine kinase and an important anticancer therapeutic target. The activity of EGFR autophosphorylation and transphosphorylation, which induces several cell signaling pathways, has been suggested to be related to its oligomeric state. However, the oligomeric states of EGFRs induced by EGF binding and the receptor–ligand stoichiometry required for its activation are still controversial. In the present study, we performed Förster resonance energy transfer (FRET) measurements by combining the coiled-coil tag–probe labeling method and spectral imaging to quantitatively analyze EGFR oligomerization on living CHO-K1 cell membranes at physiological expression levels. In the absence of its ligands, EGFRs mainly existed as monomers with a small fraction of predimers (~ 10%), whereas ~ 70% of the EGFRs formed dimers after being stimulated with the ligand EGF. Ligand-induced dimerization was not significantly affected by the perturbation of membrane components (cholesterol or monosialoganglioside GM3). We also investigated both dose and time dependences of EGF-dependent EGFR dimerization and autophosphorylation. The formation of dimers occurred within 20 s of the ligand stimulation and preceded its autophosphorylation, which reached a plateau 90 s after the stimulation. The EGF concentration needed to evoke half-maximum dimerization (~ 1 nM) was lower than that for half-maximum autophosphorylation (~ 8 nM), which suggested the presence of an inactive dimer binding a single EGF molecule.     

The effect of active pedaling combined with electrical stimulation on spinal reciprocal inhibition

ObjectivePedaling is widely used for rehabilitation of locomotion because it induces muscle activity very similar to locomotion. Afferent stimulation is important for the modulation of spinal reflexes. Furthermore, supraspinal modulation plays an important role in spinal plasticity induced by electrical stimulation. We, therefore, expected that active pedaling combined with electrical stimulation could induce strong after-effects on spinal reflexes.DesignTwelve healthy adults participated in this study. They were instructed to perform 7 min of pedaling. We applied electrical stimulation to the common peroneal nerve during the extension phase of the pedaling cycle. We assessed reciprocal inhibition using a soleus H-reflex conditioning-test paradigm. The magnitude of reciprocal inhibition was measured before, immediately after, 15 and 30 min after active pedaling alone, electrical stimulation alone and active pedaling combined with electrical stimulation (pedaling + ES).ResultsThe amount of reciprocal inhibition was significantly increased after pedaling + ES. The after-effect of pedaling + ES on reciprocal inhibition was more prominent and longer lasting compared with pedaling or electrical stimulation alone.ConclusionsPedaling + ES could induce stronger after-effects on spinal reciprocal inhibitory neurons compared with either intervention alone. Pedaling + ES might be used as a tool to improve locomotion and functional abnormalities in the patient with central nervous lesion.     

Estimating the cortex and autonomic nervous activity during a mental arithmetic task

The cerebral cortex has massive connections with autonomic nervous system and then arouses cardiovascular events, but the coupling mechanism between brain and heart is not clear. In this study the heart rate variability (HRV) and directed transfer function (DTF) methods are used to investigate the cortico-cortical functional coupling and direction of information flow between brain and heart during a mental arithmetic (MA) task. Electroencephalogram (EEG) and ECG were used for measuring neural/cardiac activity. Forty-three healthy male subjects were voluntarily participated in the study. Our results showed compared with control, LF/HF and LFn significantly increased while HF, HFn and total power significantly decreased (P < 0.05) during MA task. HR (79 ± 1.7 beats/min) was also significantly higher compared with the control (71 ± 1.4 beats/min). Moreover, MA task trigger the neurons of pre-central and central areas and then information transmit from front to back, and finished information integration at parietal and occipital locations. Our findings suggested that MA task caused an increase of the coupling of brain regions and quickened heart rate by virtue of increasing sympathetic activity and decreasing parasympathetic activity. The regulation from post-central areas to heart as well as feedback regulation from heart to central areas exists in the MA task.     

A visual patient feedback device using optical surface measurement for the cooperative management of setup and body dynamics during radiotherapy

In this technical note we describe a real-time visual feedback device for use during radiotherapy treatment. The device displays a patient's live pose and position, relative to a reference, to them, helping them to control and maintain their motion. The device uses an optical sensor system developed at The Christie NHS Foundation Trust that is capable of real-time performance of up to 24 unique wide-area body surface measurements per second. The feedback device has integrated audio and three intuitive visualisation modes designed to show different levels of detail with varying degrees of complexity: a ‘2D traffic-light display’, ‘3D flexing lamina display’ and ‘3D colour-mapped surface display’. The performance characteristics of the system were measured, with the frame rate, throughput and latency of the feedback device being 22.4 fps, 47.0 Mbps, 109.8 ms, and 13.7 fps, 86.4 Mbps, 119.1 ms for single and three-channel modes respectively. We additionally present a novel fast method for calculating the vertical displacement map of two 3D surfaces suitable for live, real time display and evaluate its precision with respect to other methodologies.     

The impact of heavy metals on the activity of some enzymes along the barley root

Barley seedlings 48 h after the onset of germination on filter paper treated for 24 h by 1 mM cadmium (Cd), 3 mM nickel (Ni) or 0.5 mM mercury (Hg) showed similar approximately 45% root growth inhibition. Although root growth inhibition was similar, loss of cell viability evaluated, as Evans blue uptake was distinct among Cd, Ni and Hg treated roots. While Cd and Hg caused cell death along the whole barley root (0–8 mm), Ni induced significant loss of cell viability only in root cells 6–8 mm distance from the root tip. Our results suggest that different metabolic processes are activated in different parts of barley root in relation to distance from the root tip during heavy metal (HM) treatment. Some of them are characteristic for several HMs such as inhibition of ascorbic acid oxidase or glutathione-S-transferase stimulation, while others are specific for individual HMs, e.g. activation of acid phosphatase and lipoxygenase by Cd and Hg, or inhibition of ascorbate peroxidase by Ni and Hg treatment.     

Glucose and xylose stimulation of a β-glucosidase from the thermophilic fungus Humicola insolens: A kinetic and biophysical study

β-Glucosidases activated by glucose and xylose are uncommon yet intriguing enzymes that may enhance cellulose saccharification efficiency, and are of interest for application in bioethanol production processes. The molecular mechanisms of activation are completely unknown, and the aim of this study was the kinetic and biophysical characterization of the stimulation of a β-glucosidase from Humicola insolens by glucose and xylose. The effects of the monosaccharides were concentration dependent, where in a stimulatory range (0.1–50 mmol L⁻¹), the activity increased up to 2-fold; in a stimulatory-inhibitory range (50–450 mmol L⁻¹ glucose or 50–730 mmol L⁻¹ xylose), the enzyme continued to be stimulated, but the activity was lower than maximal. Above 450 mmol L⁻¹ glucose or 730 mmol L⁻¹ xylose, increasing inhibition occurred. Dynamic light scattering confirmed that the enzyme is monomeric (54 kDa) and kinetic, intrinsic tryptophan fluorescence emission and far ultraviolet circular dichroism analyses indicated that the enzyme possesses a catalytic site (CS) and a modulator binding site (MS). Glucose or xylose binding to the MS induces conformational changes that stimulate the catalytic activity at the CS. Glucose and xylose may compete with the substrate for the CS while the substrate competes with the monosaccharides for binding to the MS. The stimulation of the enzymatic activity by glucose and xylose, which compete for the same sites on the enzyme molecule, is not synergistic. These data reveal allosteric interactions between the MS and the CS in H. insolens β-glucosidase that result in fine modulation of the catalytic activity by the monosaccharides. A kinetic model was developed that accurately described the experimental data for enzyme stimulation by glucose and/or xylose. Understanding the regulatory mechanisms of the enzyme activity, with the aid of kinetic models, may be useful for the application of the enzyme in cellulose hydrolysis processes.     

Brain activity during the memorization of visual scenes from TV commercials: An application of high resolution EEG and steady state somatosensory evoked potentials technologies

The aim of this study was to elucidate if the TV commercials that were remembered by the subjects after their observation within a documentary elicited particular brain activity when compared to the activity generated during the observation of TV commercials that were forgotten. High resolution EEG recordings were performed in a group of 10 healthy subjects with the steady state somatosensory evoked potentials (SSSEPs) technique, in which a series of light electrical stimulation at the left wrist were delivered at the frequency of 20 Hz. The brain activity was indexed by the phase delay of the EEG spectral responses at 20 Hz with respect to the stimulus delivering and evaluated at the scalp level as well as at the cortical surface using several regions of interest coincident with the Brodmann areas (BAs). Results suggest that the cerebral processes involved during the observation of TV commercials that were remembered by the population examined (RMB dataset) are generated by the posterior parietal cortices and the prefrontal areas, rather bilaterally. These results are compatible with previously results obtained in literature by using MEG and fMRI devices during similar experimental tasks. High resolution EEG is able to summarize, with the use of SSSEPs methodologies, the behavior of the estimated cortical networks subserving the proposed memory tasks. It is likely that such tool could play a role in the next future for the investigation of the neural substrates of the human behavior in decision-making and recognition tasks.     

Neural pattern dynamics in an oscillator model of the thalamo-reticular system.

One of development issues for information processing with synchronous oscillations in the brain is how new information is coded and how a comparison with already existing information is performed. In the present work we study a simple neural network model of the thalamo-reticular system based on the Wilson-Cowan model of neuronal oscillatory behavior. Our results show that both cortical control over the thalamus and external sensory input are essential in coordinating and generating spatio-temporal patterns of synchronous activity. A main finding of the numerical simulations is that the network connectivity and the intrinsic oscillatory properties of the neurons result in distinct collective behaviors within the network. By varying the connectivity schemes comparable with lesionated or damaged brain regions our results are in good agreement with in vivo experimental results. Suppressing the sensory input results in temporal oscillatory activity in the beta and gamma range and a strong spatial dependence of the network activity.     

Modelling potential wildlife-vehicle collisions (WVC) locations using environmental factors and human population density: A case-study from 3 state highways in Central California

Roads can exert direct and indirect impacts on ecosystems and organisms. In particular, wildlife-vehicle collisions (WVC) may be a considerable threat for populations of certain wildlife species. Despite such threat, there is still incomplete understanding of the factors responsible for high road mortality. Only a few empirical studies have tested the idea that spatial variation of roadkill is affected by environmental characteristics and socio-demographic factors. This study examines the relationships between WVC involving different taxonomic groups (i.e. ungulate, avian, medium mammal, small mammal) and physical and human population characteristics of landscapes by adapting the ecological model, Maxent, to distribution modelling of carcasses resulting from WVC. We used observations from the California Roadkill Observation System of four taxonomic groups recorded along highways in northern California. Our results indicated that current carcass-observation locations were explained primarily by total forest area (cells) within 500 m buffer and road density within a 500 m neighborhood. Our results found that current carcass-observation locations are modelled well using environmental variables and human population density together. Moreover, a comparison of projected potential roadkill locations based on environmental factors and human population density among different taxonomic groups revealed substantially different distributions. These results indicate potential areas where wildlife populations are at increased risk of coming into contact with traffic and the potential utility of this methodology for modelling current and future distributions of wildlife across landscapes using the Maxent approach.     

Reverse Na+/Ca2+-exchange mediated Ca2+-entry and noradrenaline release in Na+-loaded peripheral sympathetic nerves

[³H]noradrenaline ([³H]NA) released from sympathetic nerves in the isolated main pulmonary artery of the rabbit was measured in response to field stimulation (2 Hz, 1 ms, 60 V for 3 min) in the presence of uptake blockers (cocaine, 3 × 10⁻⁵ M and corticosterone, 5 × 10⁻⁵ M). The [³H]NA-release was fully blocked by the combined application of the selective and irreversible ‘N-type’ voltage-sensitive Ca²⁺-channel (VSCC)-blocker ω-conotoxin (ω-CgTx) GVIA (10⁻⁸ M) and the ‘non-selective’ VSCC-blocker aminoglycoside antibiotic neomycin (3 × 10⁻³ M). Na⁺-loading (Na⁺-pump inhibition by K⁺-free perfusion) was required to elicit further NA-release after blockade of VSCCs (ω-CgTx GVIA + neomycin). In K⁺-free solution, in the absence of functioning VSCCs (ω-CgTx GVIA + neomycin), the fast Na⁺-channel activator veratridine (10⁻⁵ M) further potentiated the nerve-evoked release of [³H]NA. This NA-release was significantly inhibited by KB-R7943, and fully blocked by $\text{C}{\text{a}}_{\text{o}}^{2+}-\text{removal}$. However, Li⁺-substitution was surprisingly ineffective. The non-selective K⁺-channel blocker 4-aminopyridine (4-AP, 10⁻⁴ M) also further potentiated the nerve-evoked release of NA in K⁺-free solution. This potentiated release was concentration-dependently inhibited by KB-R7943, significantly inhibited by Li⁺-substitution and abolished by $\text{C}{\text{a}}_{\text{o}}^{2+}-\text{removal}$.It is concluded that in Na⁺-loaded sympathetic nerves, in which the VSCCs are blocked, the reverse Na⁺/Ca²⁺-exchange-mediated Ca²⁺-entry is responsible for transmitter release on nerve-stimulation. Theoretically we suppose that the fast Na⁺-channel and the exchanger proteins are close to the vesicle docking sites.     

KMUP-1 ameliorates monocrotaline-induced pulmonary arterial hypertension through the modulation of Ca2+ sensitization and K+-channel

AimsThis study investigates the actions of KMUP-1 on RhoA/Rho-kinase (ROCK)-dependent Ca²⁺ sensitization and the K⁺-channel in chronic pulmonary arterial hypertension (PAH) rats.Main methodsSprague–Dawley rats were divided into control, monocrotaline (MCT), and MCT + KMUP-1 groups. PAH was induced by a single intraperitoneal injection (i.p.) of MCT (60 mg/kg). KMUP-1 (5 mg/kg, i.p.) was administered once daily for 21 days to prevent MCT-induced PAH. All rats were sacrificed on day 22.Key findingsMCT-induced increased right ventricular systolic pressure (RVSP) and right ventricular hypertrophy were prevented by KMUP-1. In myograph experiments, KCl (80 mM), phenylephrine (10 µM) and K⁺ channel inhibitors (TEA, 10 mM; paxilline, 10 µM; 4-AP, 5 mM) induced weak PA contractions in MCT-treated rats compared to controls, but the PA reactivity was restored in MCT + KMUP-1-treated rats. By contrast, in β-escin- or α-toxin-permeabilized PAs, CaCl₂-induced (1.25 mM, pCa 5.1) contractions were stronger in MCT-treated rats, and this action was suppressed in MCT + KMUP-1-treated rats. PA relaxation in response to the ROCK inhibitor Y27632 (0.1 μM) was much higher in MCT-treated rats than in control rats. In Western blot analysis, the expression of Ca²⁺-activated K⁺ (BK_Ca) and voltage-gated K⁺ channels (Kv2.1 and Kv1.5), and ROCK II proteins was elevated in MCT-treated rats and suppressed in MCT + KMUP-1-treated rats. We suggest that MCT-treated rats upregulate K⁺-channel proteins to adapt to chronic PAH.SignificanceKMUP-1 protects against PAH and restores PA vessel tone in MCT-treated rats, attributed to alteration of Ca²⁺ sensitivity and K⁺-channel function.