Blocker Of Ca2 Research Articles

Butyrlycholine esterase inhibitory activity and effects of extracts (fruit, bark and leaf) from Zanthoxylum armatum DC in gut, airways and vascular smooth muscles

BackgroundFruit, bark and leaves of Zanthoxylum armatum DC are popular remedies for gastrointestinal, cardiovascular and respiratory disorders in the subcontinent traditional practices. The aim of the study was to individually probe the profile of methanol extracts from three different parts of Zanthoxylum armatum.MethodsThe ex-vivo muscle relaxant effects of extracts were assessed in the isolated intestine, trachea and thoracic aortic rings and were compared with the positive controls and CRC were constructed. The anti-diarrheal effect of extracts was evaluated in mice by inducing diarrhea with castor oil. The extracts were also studied for acute toxicity and butyrylcholine esterase inhibition.ResultsThe extracts from fruit, bark and leaves of Z. armatum showed inhibitory effect against the butyrylcholine esterase enzyme with percent inhibition of 50.75 ± 1.23, 82.57 ± 1.33, and 37.52 ± 1.11respectively, compared to standard serine (IC50: 0.04 ± 0.001 μmol/L). The fruit and bark extracts provided 75, and 52% diarrheal protection, compared to verapamil (96%). In isolated rabbit jejunum strips, increasing addition of the extracts inhibited the spontaneous and high K+ precontractions with EC50 values of 0.71 and 3 mg/mL for fruit, EC50 values of 0.61 and 0.5 mg/mL for bark, EC50 0.81 and 3.1 mg/mL for leaves, like verapamil. The extracts induced a concentration-dependent relaxation of the carbachol (1 μM) and high K+ (80 mM) precontractions with EC50 values of 2.4 and 0.9 mg/mL for fruit, EC50 values of 1.2 and 3 for leaves. The bark extract was equipotent against both contractions with EC50 3.1 and 0.7 mg/mL, respectively. In the aortic rings, the fruit extract completely relaxed the phenylephrine (1 μM)-induced contractions with (EC50 value = 0.8 mg/ml) and a partial inhibition of high K+ induced contractions. The leaves extract completely relaxed the aortic contractions with (EC50 values = 1.0 and 8.5 mg/ml). The extracts caused no acute toxicity up to 3 g/kg dose.ConclusionsThe experiments revealed that the extracts of aerial parts of Z. armatum have antidiarrheal properties in vivo and showed spasmolytic effect in intestinal and tracheal preparations with possible mechanism involving the blockage of Ca++ channels. These experiments provide enough justification for use of this plant in ethnomedicine in diarrhea, gut and bronchial spasms.

084 Bromelain Induces Relaxation of Human Corpus Cavernosum Tissue in Vitro Independent Nitric Oxide-cGMP Pathway: Possible Significance for Erectile Dysfunction

Bromelain (BRM) is a mixture of proteolytic enzymes found in several parts of the pineapple (Ananas comosus) plant. BRM is widely administered for its well-recognized properties, mainly anti-inflammatory, antithrombotic and fibrinolytic, anticancer, and immunomodulatory. BRM gained universal acceptance as a phytotherapeutic agent due to its extensive dietary usage and lack of side effects; however, the complete molecular mechanism of action of BRM has not been completely identified. This exploratory study focuses on the erectile responses of human cavernosal strips on isometric tension measurements. To evaluate the effectiveness of (a) pure BRM (from pineapple stem, Sigma-Aldrich, St Louis, MO), (b) BRM dietary supplement (BG, Natural Brand Bromelain 500mg tablet, GNC, Pittsburgh, PA) and (c) fresh pineapple juice (PAJ) on human corpus cavernosum (HCC). HCC tissues were obtained from men undergoing penile prosthesis implantation (n =8-10) and prepared for organ bath experiments as per our published procedures. BRM-induced relaxation response (10−8-10−3 M) was performed in vitro using HCC strips in an organ bath. The effects of inhibitors [NG-nitro-L-arginine methyl ester (L-NAME, 100μM), 1H-[1,2,4]-oxadiazolole-[4,3-a] quinoxalin-10one (ODQ, 30μM), and tetraethylammonium (TEA, 100 μM, blocker Ca2+ - activated K+ channels)] on BRM-mediated relaxation responses were evaluated. The relaxation effects of BRM, BG, and PAJ on phenylephrine (Phe)-induced contraction were also compared. The protein expression of endothelial (e) and neuronal (n) nitric oxide synthase (NOS) markers and vascular endothelium growth factor (VEGF) were determined using Western blotting and immunohistochemistry.

Alterations of Calcium Channels in a Mouse Model of Huntington's Disease and Neuroprotection by Blockage of CaV1 Channels.

Huntington’s disease (HD) is a neurodegenerative autosomal dominant disorder, characterized by symptoms of involuntary movement of the body, loss of cognitive function, psychiatric disorder, leading inevitably to death. It has been previously described that higher levels of brain expression of Cav1 channels are involved in major neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease. Our results demonstrate that a bacterial artificial chromosome (BAC)-mediated transgenic mouse model (BACHD mice) at the age of 3 and 12 months exhibits significantly increased Cav1.2 protein levels in the cortex, as compared with wild-type littermates. Importantly, electrophysiological analyses confirm a significant increase in L-type Ca2+ currents and total Ca2+ current density in cortical neurons from BACHD mice. By using an in vitro assay to measure neuronal cell death, we were able to observe neuronal protection against glutamate toxicity after treatment with Cav1 blockers, in wild-type and, more importantly, in BACHD neurons. According to our data, Cav1 blockers may offer an interesting strategy for the treatment of HD. Altogether, our results show that mutant huntingtin (mHtt) expression may cause a dysregulation of Cav1.2 channels and we hypothesize that this contributes to neurodegeneration during HD.

Diffusion and Interaction between ion Ca2+ and ion Gd3+ in a Model Synapse: A Monte Carlo Study

Gadolinium (Gd3+) is a commonly used in MRI. The role of Gd3+ as contrast agent greatly helps to improve the quality of an image and Gadolinium entrance in a body through a diffusion process after administration. Diffusion process takes place from outside pre-synapse to inside pre-synapse through Ca2+ channels. This process causes a delay of Ca2+ in passing Ca2+ channels to pre-synapse. This study aims to determine equilibrium concentration of Ca2+ and Gd3+ so that Ca2+ can pass Ca2+ channels. To address the effect of Gd3+ concentration around Ca2+ channels, we developed a Monte Carlo simulation on Ca diffusion and interaction with Gd. We find Gd3+ concentration in a certain threshold can be potential as a blocker Ca2+ diffuse entrance into pre-synapse. In another hand, an amount of Ca2+ channels and pre-synapse terminal to continuing diffusion of vesicles to clef was important. And the trapping Gd3+ in pre-synapse effects in diffusion delays also. These simulations identify characteristics of the interaction between Ca2+ and Gd3+ in Ca channels which entrance into pre-synapse through diffusion process depend on concentration with each other.

Store-operated calcium channels: Potential target for the therapy of hypertension

Effective therapy of hypertension represents a key strategy for reducing the burden of cardiovascular disease and its associated mortality. The significance of voltage dependent L-type Ca²⁺ channels to Ca²⁺ influx, and of their regulatory mechanisms in the development of heart disease, is well established. A wide variety of L-type Ca²⁺ channel inhibitors and Ca²⁺ antagonists have been found to be beneficial not only in the treatment of hypertension, but also in myocardial infarction and heart failure. Over the past two decades, another class of Ca²⁺ channel - the voltage independent store-operated Ca²⁺ channel - has been implicated in the regulation and fine tuning of Ca²⁺ entry in both cardiac and smooth muscle cells. Store-operated Ca²⁺ channels are activated by the depletion of Ca²⁺ stores within the endoplasmic/sarcoplasmic reticulum, or by low levels of cytosolic Ca²⁺, thereby facilitating agonist-induced Ca²⁺ influx. Store-operated Ca²⁺ entry through this pivotal pathway involves both stromal interaction molecule (STIM) and Orai channels. Different degrees of changes in these proteins are considered to promote Ca²⁺ entry and hence contribute to the pathogenesis of cardiovascular dysfunction. Several blockers of store-operated Ca²⁺ channels acting at the level of both STIM and Orai channels have been shown to depress Ca²⁺ influx and lower blood pressure. However, their specificity, safety, and clinical significance remain to be established. Thus, there is an ongoing challenge in the development of selective inhibitors of store-operated Ca²⁺ channels that act in vascular smooth muscles for the improved treatment of hypertension.

Features of ionic transport processes in a model of arterial hypertension

Aim.To study the ionic mechanisms which underlie regulation contractile activity of vascular smooth muscles and the erythrocytes membrane potential from spontaneously hypertensive rats.Materials and methods.The effect of acetylcholine (ACX), 10 μM, and Ca2+ -ionophore A23187, 10 μM, on the contractile reactions of isolated smooth muscle segments of the aorta from 11-week-old spontaneously hypertensive rats (SHR) and Wistar – Kyoto rats (WKY) induced by phenylephrine (PE), 1 μM, was measured by the mechanography. 11-week-old SHR were divided into control and experimental groups depending on the drug administration (amlodipine 10 mg/kg given intragastrically). Blood pressure (BP) in SHR was measured before and after treatment. The amplitude of the hyperpolarizating response (HO) and the activity of Ca2+-dependent K+-channels of the erythrocyte membrane of SHR were performed with potentiometric method.Results.In response to the stimulating effect of the ACX or the calcium ionophore A23187, the smooth muscle segments of the aorta from the WKY and SHR precontracted with PE were relaxed. To the addition of the ACX, the vascular segments of the SHR responded with a stronger dilatation than the WKY segments, but not the action of the Ca2+-ionophore. Treatment of SHR with blocker of Ca2+-channels of L-type amlodipine caused a decrease the BP, and an increase in the relaxing effect of intact aortic segments on the ACX and Ca2+-ionophore. There was an increase the amplitude of HO and activity of Ca2+-dependent K+-channels of the erythrocyte membrane from SHR.Conclusion.Relaxation of vascular smooth muscle in SHR is caused by changes in the endothelial function and Ca2+-dependent ionic conductivity of the myocyte membrane. An increase of the hyperpolarizating response of the erythrocyte membrane from rats with spontaneous hypertension is associated with activation of potassium channels. The selective effect on these intracellular targets can serve as a basis for the development of antihypertensive drugs.

Opposite Roles in Short-Term Plasticity for N-Type and P/Q-Type Voltage-Dependent Calcium Channels in GABAergic Neuronal Connections in the Rat Cerebral Cortex.

Neurotransmitter release is triggered by Ca2+ influx through voltage-dependent Ca2+ channels (VDCCs). Distinct expression patterns of VDCC subtypes localized on the synaptic terminal affect intracellular Ca2+ dynamics induced by action potential-triggered Ca2+ influx. However, it has been unknown whether the expression pattern of VDCC subtypes depends on each axon terminal or neuronal subtype. Furthermore, little information is available on how these VDCC subtypes regulate the release probability of neurotransmitters. To address these questions, we performed multiple whole-cell patch-clamp recordings from GABAergic neurons in the insular cortex of either the male or the female rat. The paired-pulse ratio (PPR; 50 ms interstimulus interval) varied widely among inhibitory connections between GABAergic neurons. The PPR of unitary IPSCs was enhanced by ω-conotoxin GVIA (CgTx; 3 μm), an N-type VDCC blocker, whereas blockade of P/Q-type VDCCs by ω-agatoxin IVA (AgTx, 200 nm) decreased the PPR. In the presence of CgTx, application of 4 mm [Ca2+]o or of roscovitine, a P/Q-type activator, increased the PPR. These results suggest that the recruitment of P/Q-type VDCCs increases the PPR, whereas N-type VDCCs suppress the PPR. Furthermore, we found that charybdotoxin or apamin, blockers of Ca2+-dependent K+ channels, with AgTx increased the PPR, suggesting that Ca2+-dependent K+ channels are coupled to N-type VDCCs and suppress the PPR in GABAergic neuronal terminals. Variance-mean analysis with changing [Ca2+]o showed a negative correlation between the PPR and release probability in GABAergic synapses. These results suggest that GABAergic neurons differentially express N-type and/or P/Q-type VDCCs and that these VDCCs regulate the GABA release probability in distinct manners.SIGNIFICANCE STATEMENT GABAergic neuronal axons target multiple neurons and release GABA triggered by Ca2+ influx via voltage-dependent Ca2+ channels (VDCCs), including N-type and P/Q-type channels. Little is known about VDCC expression patterns in GABAergic synaptic terminals and their role in short-term plasticity. We focused on inhibitory synaptic connections between GABAergic neurons in the cerebral cortex using multiple whole-cell patch-clamp recordings and found different expression patterns of VDCCs in the synaptic terminals branched from a single presynaptic neuron. Furthermore, we observed facilitative and depressive short-term plasticity of IPSCs mediated by P/Q-type and N-type VDCCs, respectively. These results suggest that VDCC expression patterns regulate distinctive types of synaptic transmission in each GABAergic axon terminal even though they are branched from a common presynaptic neuron.

Vasorelaxant effects of diarylheptanoids, acerogenin A and (−)‐centrolobol from the bark of Acer nikoense

ABSTRACTAimThe bark of Acer nikoense (Aceraceae) is used in Japanese folk medicine as a remedy for hepatic disorders and eye diseases. The aim of this study was to investigate the vasorelaxant effects of A. nikoense extracts and further clarify the active constituents and mechanisms of action.MethodsDried A. nikoense bark was extracted with methanol. The extract was further extracted with diethyl ether, ethyl acetate, and 1‐butanol, successively. The major constituents of the extracts were isolated using chromatography. Vasorelaxant effects of the extracts and isolated constituents were assessed using isolated rat aorta. The aorta was placed in a well‐oxygenated bath of modified Krebs–Henseleit solution and the mechanical tension measured isometrically.ResultsThe extracts had a vasorelaxant effect on aorta precontracted with 3 × 10−7 mol/L norepinephrine (NE). Isolated major constituents of A. nikoense bark, diarylheptanoids, such as acerogenin A (compound 1), B (compound 2), (−)‐centrolobol (compound 3), aceroside I (compound 5), B1 (compound 6), VII (compound 7) III (compound 8), and phenolic compound, (+)‐rhododendrol (compound 4) were examined. Compounds 1 and 3 had vasorelaxant effects on rat aorta with or without endothelium in the NE‐induced preparation. Furthermore, compounds 1 and 3 inhibited contraction induced by a high concentration (60 mmol/L) of K+ and also had a moderate inhibitory effect on NE‐induced vasoconstriction in the presence of nicardipine.ConclusionThe inhibition of NE‐induced vasoconstriction by compounds 1 and 3 may be attributed to factors such as endothelial independency by blocking of Ca2+ influx via voltage‐dependent Ca2+ channels and receptor‐operated Ca2+ channels.

The Possible role interaction between cannabinoid and TRPC3, TRPC6 and TRPV2 in behavioral process

Most studies have found that changes in concentration of intracellular ions can change cell activation. Calcium ion is one of the most vital one of these ions which is the most vital second messenger within cells. Ca2+ is necessary for a wide range of cellular processes such as cell proliferation, muscle contraction and exocytosis and apoptosis. Different kinds of TRPCs (transient receptor potential cation channels) have a wide range of activity in cell but are known as Ca2+ blocker channel. On the other hand, cannabinoids are a class of different chemical compounds that act on cannabinoid receptors in cells that suppress neurotransmitter release in the brain. Ligands for these receptor proteins consist of endocannabinoids (produced naturally in the body of humans and animals), the phytocannabinoids (exist in cannabis and some other plants), and synthetic cannabinoids (artificially made). The most important cannabinoid is the phytocannabinoid tetrahydrocannabinol (THC), the primary psychoactive compound of cannabis. Cannabidiol (CBD) is another major part of the plant. It is showed that endocannabinoid biosynthesis is a calcium-dependent process, though the physiological source of calcium is not identified. Many of biochemical experiments have been investigating the contributions of extracellular and intracellular calcium in the biosynthetic process. Some studies found that extracellular calcium is a vital factor for the endogenous cannabinoids biosynthesis, while a simply releasing intracellular calcium store such as endoplasmic reticulum does not have an effect on endocannabinoid biosynthesis. In addition to introduction of cannabinoid, blocker of Ca2+ channel (TRPC) and investigating interaction among them in this review, the possible role of cannabinoid and TRPC3, TRPC6 and TRPV2 in behavioral process are induced in conclusion.

Role of mucosa in generating spontaneous activity in the guinea pig seminal vesicle.

The mucosa may have neuron-like functions as urinary bladder mucosa releases bioactive substances that modulate sensory nerve activity as well as detrusor muscle contractility. However, such mucosal function in other visceral organs remains to be established. The role of mucosa in generating spontaneous contractions in seminal vesicles (SVs), a paired organ in the male reproductive tract, was investigated. The intact mucosa is essential for the generation of spontaneous phasic contractions of SV smooth muscle arising from electrical slow waves and corresponding increases in intracellular Ca2+ . These spontaneous events primarily depend on Ca2+ handling by sarco-endoplasmic reticulum Ca2+ stores. A population of mucosal cells developed spontaneous rises in intracellular Ca2+ relying on sarco-endoplasmic reticulum Ca2+ handling. The spontaneously active cells in the SV mucosa appear to drive spontaneous activity in smooth muscle either by sending depolarizing signals and/or by releasing humoral substances. The role of the mucosa in generating the spontaneous activity of guinea-pig seminal vesicle (SV) was explored. Changes in contractility, membrane potential and intracellular Ca2+ dynamics of SV smooth muscle cells (SMCs) were recorded using isometric tension recording, intracellular microelectrode recording and epi-fluorescence Ca2+ imaging, respectively. Mucosa-intact but not mucosa-denuded SV preparations generated TTX- (1μm) resistant spontaneous phasic contractions that were abolished by nifedipine (3μm). Consistently, SMCs developed mucosa-dependent slow waves (SWs) that triggered action potentials and corresponding Ca2+ flashes. Nifedipine (10μm) abolished the action potentials and spontaneous contractions, while suppressing the SWs and Ca2+ flashes. Both the residual SWs and spontaneous Ca2+ transients were abolished by cyclopiazonic acid (CPA, 10μm), a sarco-endoplasmic reticulum Ca2+ -ATPase (SERCA) inhibitor. DIDS (300μm) and niflumic acid (100μm), blockers for Ca2+ -activated Cl- channels (CACCs), or low Cl- solution also slowed or prevented the generation of SWs. In SV mucosal preparations detached from the muscle layer, a population of mucosal cells generated spontaneous Ca2+ transients that were blocked by CPA but not nifedipine. These results suggested that spontaneous contractions and corresponding Ca2+ flashes in SV SMCs arise from action potential generation due to the opening of L-type voltage-dependent Ca2+ channels. Spontaneous Ca2+ transients appear to primarily result from Ca2+ release from sarco-endoplasmic reticulum Ca2+ stores to activate CACCs to develop SWs. The mucosal cells firing spontaneous Ca2+ transients may play a critical role in driving spontaneous activity of SV smooth muscle either by sending depolarizing signals or by releasing humoral substances.

Ca2+-permeable AMPA receptors in mouse olfactory bulb astrocytes

Ca2+ signaling in astrocytes is considered to be mainly mediated by metabotropic receptors linked to intracellular Ca2+ release. However, recent studies demonstrate a significant contribution of Ca2+ influx to spontaneous and evoked Ca2+ signaling in astrocytes, suggesting that Ca2+ influx might account for astrocytic Ca2+ signaling to a greater extent than previously thought. Here, we investigated AMPA-evoked Ca2+ influx into olfactory bulb astrocytes in mouse brain slices using Fluo-4 and GCaMP6s, respectively. Bath application of AMPA evoked Ca2+ transients in periglomerular astrocytes that persisted after neuronal transmitter release was inhibited by tetrodotoxin and bafilomycin A1. Withdrawal of external Ca2+ suppressed AMPA-evoked Ca2+ transients, whereas depletion of Ca2+ stores had no effect. Both Ca2+ transients and inward currents induced by AMPA receptor activation were partly reduced by Naspm, a blocker of Ca2+-permeable AMPA receptors lacking the GluA2 subunit. Antibody staining revealed a strong expression of GluA1 and GluA4 and a weak expression of GluA2 in periglomerular astrocytes. Our results indicate that Naspm-sensitive, Ca2+-permeable AMPA receptors contribute to Ca2+ signaling in periglomerular astrocytes in the olfactory bulb.

Ca2+/calmodulin-dependent protein kinase IIβ and IIδ mediate TGFβ-induced transduction of fibronectin and collagen in human pulmonary fibroblasts.

It is now clear that in addition to activating several complex kinase pathways (Smad, MAP kinase, PI3 kinase), TGFβ also acts by elevating cytosolic Ca2+ concentration within human pulmonary fibroblasts. Ca2+/calmodulin-dependent protein kinase II (CamK II) is also known to regulate gene expression in fibroblasts. In this study, we examined the interactions between calcium signaling, activation of CamK and other kinases, and extracellular matrix (ECM) gene expression. Human pulmonary fibroblasts were cultured and stimulated with artificially generated Ca2+ pulses in the absence of TGFβ, or with TGFβ (1 nM) or vehicle in the presence of various blockers of Ca2+ signaling. PCR and Western blotting were used to measure gene expression and protein levels, respectively. We found that Ca2+ pulses in the absence of TGFβ increased ECM gene expression in a pulse frequency-dependent manner, and that blocking Ca2+ signaling and the CamK II pathway significantly reduced TGFβ-mediated ECM gene expression, without having any effects on other kinase pathways (Smad, PI3 kinase, or MAP kinase). We also found that TGFβ elevated the expression of CamK IIβ and CamK IIδ, while siRNA silencing of those two subtypes significantly reduced TGFβ-mediated expression of collagen A1 and fibronectin 1. Our data suggest that TGFβ induces the expression of CamK IIβ and CamK IIδ, which in turn are activated by TGFβ-evoked Ca2+ waves in a frequency-dependent manner, leading to increased expression of ECM proteins.

The mechanism of VEGF-mediated endothelial cells survival and proliferation in conditions of unfed-culture.

The mechanisms of VEGF-mediated effects on endothelial cells during cancer development and progression is not clear. In present study the biological effects of VEGF, VEGF-rich culture medium of peritoneal macrophages from mice with Lewis lung carcinoma were studied on MAEC cell line under conditions of unfed culture. We have shown that VEGF increased cell proliferation by the 5th day of culturing vs control and anti-VEGF-treated cells. This effect was associated with increased consumption of glucose and NO production by the 2nd day while decreased – on the 5th day of cell culturing. VEGF-mediated NO production was dependent on Ca2+ ions. Block of Ca2+-channels (LaCl3) had more pronounced inhibitory effect vs chelator of Ca2+ ions (EDTA). It was shown that peritoneal macrophages are the main suppliers of VEGF at tumor angiogenesis, as evidenced by the data obtained on model system of endothelial cells synchronized in G0/G1 phase.

Functional coupling of TRPV4 channels and BK channels in regulating spontaneous contractions of the guinea pig urinary bladder.

We investigated the role of TRPV4 channels (TRPV4) in regulating the contractility of detrusor smooth muscle (DSM) and muscularis mucosae (MM) of the urinary bladder. Distribution of TRPV4 in DSM and MM of guinea-pig bladders was examined by fluorescence immunohistochemistry. Changes in the contractility of DSM and MM bundles were measured using isometric tension recording. Intracellular Ca(2+) dynamics were visualized by Cal-520 fluorescent Ca(2+) imaging, while membrane potential changes were recorded using intracellular microelectrode technique. DSM and MM expressed TRPV4 immunoreactivity. GSK1016790A (GSK, 1nM), a TRPV4 agonist, evoked a sustained contraction in both DSM and MM associated with a cessation of spontaneous phasic contractions in a manner sensitive to HC-067047 (10μM), a TRPV4 antagonist. Iberiotoxin (100nM) and paxilline (1μM), large conductance Ca(2+)-activated K(+) (BK) channel blockers restored the spontaneous contractions in GSK. The sustained contractions in DSM and MM were reduced by nifedipine (10μM), a blocker of L-type voltage-dependent Ca(2+) channels (LVDCCs) by about 40% and by nominally Ca(2+)-free solution by some 90%. GSK (1nM) abolished spontaneous Ca(2+) transients, increased basal Ca(2+) levels and also prevented spontaneous action potential discharge associated with DSM membrane hyperpolarization. In conclusion, Ca(2+) influx through TRPV4 appears to activate BK channels to suppress spontaneous contractions and thus a functional coupling of TRPV4 with BK channels may act as a self-limiting mechanism for bladder contractility during its storage phase. Despite the membrane hyperpolarization in GSK, Ca(2+) entry mainly through TRPV4 develops the tonic contraction.

Induction of heat resistance in wheat seedlings by exogenous calcium, hydrogen peroxide, and nitric oxide donor: functional interaction of signal mediators

Functional interactions of calcium ions, hydrogen peroxide, and nitric oxide as signal mediators in root cells of wheat (Triticum aestivum L.) seedlings upon induction of their heat resistance was studied with use of inhibitor-based analysis. Treatment of the seedlings with hydrogen peroxide or a combination of calcium chloride with ionophore A23187 significantly increased their content of nitric oxide, which peaked 0.5–1 h after the start of the treatment. CaCl2 or exogenous NO donor (sodium nitroprusside, SNP) transitorily increased the hydrogen peroxide level in the roots. Seedlings pretreatments with calcium chelator (EGTA), blocker of Ca2+ channels (LaCl3), inhibitor of phospholipase C (neomycin), or antagonist of cyclic adenosine-5'-diphosphatribose formation (nicotinamide) more or less prevented the rise in the nitric oxide content in roots caused by exogenous H2O2; the SNP-induced rise in hydrogen peroxide was also damped down. However, the seedlings pretreatment with antioxidants ionol or dimethylthiourea did not hinder the increase in the NO level, which was caused by exogenous Ca2+. The inhibitors of NO synthase (NG-nitro-L-arginine methyl ester, L-NAME) or nitrate reductase (sodium tungstate) did not interfere in the accumulation of H2O2 in root tissues stimulated by exogenous calcium. Calcium antagonists diminished the seedlings heat resistance increased by hydrogen peroxide or SNP. Antioxidants and inhibitors of NO synthase or nitrate reductase weakened the calcium-stimulated enhancement in the seedlings heat resistance. It was concluded that calcium may activate NO- and H2O2-generating enzymatic systems as well as participate in the transduction of signals of these mediators into genetic apparatus and in the formation of physiological reactions underlying the enhanced heat resistance.

Influencing fatty acid composition of yeasts by lanthanides.

The growth of microorganisms is affected by cultivation conditions, concentration of carbon and nitrogen sources and the presence of trace elements. One of the new possibilities of influencing the production of cell mass or lipids is the use of lanthanides. Lanthanides are biologically non-essential elements with wide applications in technology and industry and their concentration as environmental contaminants is therefore increasing. Although non-essential, lanthanides have been proposed (and even used) to produce beneficial effects in plants but their mechanisms of action are unclear. Recently, it was suggested that they may replace essential elements or operate as potent blockers of Ca(2+) channels. We tested the effect of low concentrations of lanthanides on traditional biotechnologically useful yeast species (Kluyveromyces polysporus, Saccharomyces cerevisiae, Torulospora delbrueckii), and species capable of high accumulation of lipids (Rhodotorula glutinis, Trichosporon cutaneum, Candida sp., Yarrowia lipolytica). Low concentrations of lanthanum and monazite were conducive to an increase in cell mass and lipids and also higher production of palmitoleic acid, commonly used in cosmetics and medicine, and ω6-linoleic acid which is a precursor of thromboxanes, prostaglandins and leucotrienes.

Study on the mechanisms of the bronchodilator effects of Folium Eriobotryae and the selected active ingredient on isolated guinea pig tracheal strips

Context: Folium Eriobotryae (FE), the dry leaf of Eriobotrya japonica (Thunb.) Lindl. (Rosaceae), has been widely used to treat respiratory disorders.Objective: To examine the bronchodilatory activity of FE and the potential mechanisms involved.Materials and methods: The effects of ethyl acetate fraction of FE (EFE) (0.05–0.3 mg/mL) on the isolated tracheal strips, and ursolic acid (UA) (5–30 μg/mL) that was the main constituent of EFE, were tested in vitro. Meanwhile, acetylcholine (Ach) and histamine (His)-induced bronchospasm were conducted in vivo in guinea pig. Furthermore, mechanisms of relaxant effects of EFE and UA were evaluated in the absence and presence of specific inhibitors.Results: With in vitro studies, the contractile response evoked by Ach or His (EC50 = 0.21 and 0.16 mg/mL) was decreased by EFE, and UA caused a concentration-dependent relaxation precontracted by His (EC50 = 23.2 μg/mL). With in vivo studies, EFE strongly prolonged preconvulsive time similar to isoprenalin. The bronchodilator effects of EFE could be blocked by propranolol (1 μM), NG-nitro-l-arginine methyl ester (l-NAME) (100 μM) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) (1 μM). EFE also inhibited the contraction in Ca2+-free medium and produced rightward parallel displacement of CaCl2 curves. In addition, the relaxant effects of UA could only be blocked by l-NAME and ODQ.Discussion and conclusion: These results suggest that bronchodilator activities of EFE were related to activation of β-adrenoceptor and NO/cGMP pathway. Blockage of Ca2+ channels and inhibition of IP3R-mediated internal Ca2+ release were also involved. Additionally, UA produced relaxant effects by the NO/cGMP pathway.

Myosin light chain kinase facilitates endocytosis of synaptic vesicles at hippocampal boutons.

At nerve terminals, endocytosis efficiently recycles vesicle membrane to maintain synaptic transmission under different levels of neuronal activity. Ca(2+) and its downstream signal pathways are critical for the activity-dependent regulation of endocytosis. An activity- and Ca(2+) -dependent kinase, myosin light chain kinase (MLCK) has been reported to regulate vesicle mobilization, vesicle cycling, and motility in different synapses, but whether it has a general contribution to regulation of endocytosis at nerve terminals remains unknown. We investigated this issue at rat hippocampal boutons by imaging vesicle endocytosis as the real-time retrieval of vesicular synaptophysin tagged with a pH-sensitive green fluorescence protein. We found that endocytosis induced by 200 action potentials (5-40Hz) was slowed by acute inhibition of MLCK and down-regulation of MLCK with RNA interference, while the total amount of vesicle exocytosis and somatic Ca(2+) channel current did not change with MLCK down-regulation. Acute inhibition of myosin II similarly impaired endocytosis. Furthermore, down-regulation of MLCK prevented depolarization-induced phosphorylation of myosin light chain, an effect shared by blockers of Ca(2+) channels and calmodulin. These results suggest that MLCK facilitates vesicle endocytosis through activity-dependent phosphorylation of myosin downstream of Ca(2+) /calmodulin, probably as a widely existing mechanism among synapses. Our study suggests that MLCK is an important activity-dependent regulator of vesicle recycling in hippocampal neurons, which are critical for learning and memory. The kinetics of vesicle membrane endocytosis at nerve terminals has long been known to depend on activity and Ca(2+) . This study provides evidence suggesting that myosin light chain kinase increases endocytosis efficiency at hippocampal neurons by mediating Ca(2+) /calmodulin-dependent phosphorylation of myosin. The authors propose that this signal cascade may serve as a common pathway contributing to the activity-dependent regulation of vesicle endocytosis at synapses.

Antihypertensive activity of 80% methanol seed extract of Calpurnia aurea (Ait.) Benth. subsp. aurea (Fabaceae) is mediated through calcium antagonism induced vasodilation

Ethnopharmacological relevanceCalpurnia aurea (Ait.) Benth. subsp. aurea (CASA) (Fabaceae) seeds are used to treat hypertension in Ethiopian folklore medicine, particularly by Shinasha, Agew-awi and Amhara people in northwest Ethiopia. However, the claim has so far not been substantiated scientifically. Aim of the studyThe study was conducted to evaluate the antihypertensive activity of 80% methanol extract of CASA in animal model of hypertension as well as its vasorelaxant effect and possible underlying mechanisms in isolated guinea pig aorta. Material and methodsHypotensive and antihypertensive effect of CASA extract was determined in vivo through the intravenous (iv) route in normotensive and hypertensive anesthetized rats using 2-kidney-1-clip (2K1C) rat model. Ex vivo, guinea pig thoracic aortic rings were isolated and suspended in organ bath, and the vasodepressor effects as well as the mechanism of action of the extract were studied by means of isometric tension recording experiments. ResultsThe blood pressure fell dose-dependently and significantly in renal hypertensive and normotensive rats following i.v. administration, suggesting that the hydroalcoholic extract possesses hypotensive and antihypertensive effects. The extract also caused a dose-dependent relaxation of aorta pre-contracted with KCl at a concentration of 5–250mg/L, with a maximum relaxation of 92.1% achieved at 250mg/L. The relaxation mechanism was found to be independent of the muscarinic receptors, histamine receptors, ATP dependent K+ channels, cyclooxygenase enzymes, cGMP/NO pathway and the endothelium system. The extract caused rightward shift of the Ca++ dose–response curves, similar to that caused by verapamil, indicating that it produced vasorelaxation by inhibiting extracellular Ca2+ influx. ConclusionsThe findings demonstrate that the plant is endowed with antihypertensive effect, providing evidence for its traditional use. The effect may be, at least in part, due to dilation of blood vessels through blockage of Ca2+ channels.

Systematic Review and Meta-analysis of Atrial Fibrillation Prophylaxis After Lung Surgery.

Atrial fibrillation (AF), which increases morbidity and mortality, is a common occurrence after thoracic surgery and pulmonary resection. Despite several investigations on various prophylactic measures for AF prevention, the studies were not uniform and do not use similar controls making it difficult to arrive at a meaningful conclusion. In the present systematic analysis review, we evaluated the efficacy of different prophylactic approaches to prevent AF after lung surgery in randomized trials reported during 1991-2014. A total of 12 trials were identified that met the criteria set for this meta-analysis. Among different trials, amiodarone was found to be most effective in preventing postoperative AF (risk ratio, 0.22; P < 0.0001; 95% confidence interval: 0.09-0.54). There were no significant prophylactic effects by MgSO4 (risk ratio, 1.24; P < 0.007; 95% confidence interval, 0.27-5.68), digoxin, or Ca blockers. Single use of amiodarone was able to lower the incidence of AF from 39.2% to 8.3% and seemed to be safe with no major complications. Although several prophylactic measures have been tried to curtail the incidence of AF in patients after lung surgery, prophylaxis with amiodarone seems to be most effective of treatments studied.