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acetylcholine chloride [keywords]
- Evidence for a carotid body homolog in the lizard Tupinambis merianae. [JOURNAL ARTICLE]
- J Exp Biol 2014 Dec 18.
The homolog to the mammalian carotid body has not yet been identified in lizards. Observational studies and evolutionary history provide indirect evidence for the existence of a chemoreceptor population at the first major bifurcation of the common carotid artery in lizards, but a chemoreceptive role for this area has not yet been definitively demonstrated. We explored this possibility by measuring changes in cardiorespiratory variables in response to focal arterial injections of the hypoxia mimic sodium cyanide (NaCN) into the carotid artery of 12 unanesthetized specimens of Tupinambis merianae. These injections elicited increases in heart rate (fH; 101±35% increase) and respiratory rate (fR; 620±119% increase), but not mean arterial blood pressure (MAP). These responses were eliminated by vagal denervation. Similar responses were elicited by injections of the neurotransmitters acetylcholine (ACh) and serotonin (5-HT) but not norepinephrine. Heart rate and respiratory rate increases in response to NaCN could be blocked or reduced by either the antagonist to ACh (atropine) and/or 5-HT (methysergide). Finally, using immunohistochemistry we demonstrated the presence of putative chemoreceptive cells immuno-positive for the cholinergic cell marker vesicular ACh transporter (VAChT) and 5-HT on internal lattice-like structures at the carotid bifurcation. These results provide evidence for the existence of dispersed chemoreceptor cells at the first carotid bifurcation in the central cardiovascular area in lizards with similar properties to known carotid body homologs, adding to the picture of chemoreceptor evolution in vertebrates.
- Impaired coronary artery distensibility is an endothelium-dependent process and is associated with vulnerable plaque composition. [JOURNAL ARTICLE]
- Clin Physiol Funct Imaging 2014 Dec 18.
Coronary endothelial-dependent microvascular dysfunction, an early reversible stage of coronary artery disease (CAD), is associated with poor clinical outcome. The current study investigated whether coronary artery distensibility index (CDI) is associated with: (i) coronary endothelial-dependent microvascular dysfunction and (ii) vulnerable plaque composition among subjects with non-obstructive CAD. Seventy-four subjects with non-obstructive CAD (luminal stenosis <30%) were studied. In 20 subjects with and without coronary endothelial-dependent microvascular dysfunction, coronary flow reserve (CFR) of target segment during intracoronary (IC) infusion of acetylcholine (Ach) and bolus injection of adenosine as well as CDI at rest of corresponding target segment were measured. In 54 subjects, plaque compositions and CDI at rest of 154 non-obstructive coronary segments as well as proximal segment without disease were measured by intravascular ultrasound (IVUS). CDI was defined as: [(Early-diastolic cross-sectional-area (CSA) - End-diastolic CSA of target segment)/(end-diastolic CSA of target segment × coronary-pulse-pressure) × 10(3) ]. There is a direct association between endothelial dysfunction and impaired CDI of a coronary segment both in the given coronary segment and corresponding microvessels in which a strong agreement between CDI and CFR Ach (r(2) = 0·85, P = 0·0001) was observed. Multivariable regression-analysis showed that CDI was an independent predictor of the vulnerable plaque characteristics. The risk of impaired CDI was 125% higher in segments with necrotic core and 60% higher in segments with fibrofatty components as compared to normal segments (P = 0·001). In conclusions, the current study reveals that impaired CDI is an endothelial-dependent process of both given coronary segment and corresponding microvessels and is associated with vulnerable plaque composition.
- Association Between Arterial Stiffness and Skin Microvascular Function: The SUVIMAX2 Study and The Maastricht Study. [JOURNAL ARTICLE]
- Am J Hypertens 2014 Dec 17.
It has been hypothesized that arterial stiffness leads to generalized microvascular dysfunction and that individuals with type 2 diabetes mellitus (T2DM) are particularly prone to the detrimental effects of arterial stiffness. However, evidence for an association between stiffness and markers of generalized microvascular dysfunction is lacking. We therefore investigated the association between arterial stiffness and skin microvascular function in individuals without and with T2DM.Cross-sectional data were used of The Supplementation en Vitamines et Mineraux Antioxydants 2 (SUVIMAX2) Study (n = 284/62.2 years/48.6% women/0% T2DM (by design)) and The Maastricht Study (n = 737/59.7 years/45.2% women/28.8% T2DM (by design)). Arterial stiffness was determined by carotid-femoral pulse wave velocity (cfPWV). Skin capillaroscopy was used to determine capillary density at baseline, and during reactive hyperemia and venous congestion. Laser Doppler flowmetry was used to assess acetylcholine- and local heating-induced vasoreactivity, and skin flowmotion.In The SUVIMAX2 Study, cfPWV (per +1 SD) was not associated with baseline capillary density (regression coefficient: -0.48 (95% confidence interval: 2.37; 1.41)) or capillary recruitment during venous congestion (0.54% (-0.74; 1.81%)). In addition, cfPWV was not associated with acetylcholine (-0.02% (-0.14; 0.10%)) or local heating-induced vasoreactivity (0.03% (-0.07; 0.12%)). In The Maastricht Study, in individuals without T2DM, cfPWV was not associated with baseline capillary density (-1.20 (-3.17; 0.77)), and capillary recruitment during reactive hyperemia (1.22% (-0.41; 2.84%)) or venous congestion (1.50% (-0.25; 3.25%)). In addition, cfPWV was not associated with flowmotion (-0.01 (-0.07; 0.06)). Results were adjusted for age and sex. Additional adjustments for confounders did not materially change these results. Results were qualitatively similar in individuals with T2DM.Arterial stiffness is not associated with skin microvascular function, irrespective of the presence of T2DM.
- The subpopulation of microglia expressing functional muscarinic acetylcholine receptors expands in stroke and Alzheimer's disease. [JOURNAL ARTICLE]
- Brain Struct Funct 2014 Dec 19.
Microglia undergo a process of activation in pathology which is controlled by many factors including neurotransmitters. We found that a subpopulation (11 %) of freshly isolated adult microglia respond to the muscarinic acetylcholine receptor agonist carbachol with a Ca(2+) increase and a subpopulation of similar size (16 %) was observed by FACS analysis using an antibody against the M3 receptor subtype. The carbachol-sensitive population increased in microglia/brain macrophages isolated from tissue of mouse models for stroke (60 %) and Alzheimer's disease (25 %), but not for glioma and multiple sclerosis. Microglia cultured from adult and neonatal brain contained a carbachol-sensitive subpopulation (8 and 9 %), which was increased by treatment with interferon-γ to around 60 %. This increase was sensitive to blockers of protein synthesis and correlated with an upregulation of the M3 receptor subtype and with an increased expression of MHC-I and MHC-II. Carbachol was a chemoattractant for microglia and decreased their phagocytic activity.
- Inhibition of Nicotinic Acetylcholine Receptors, a Novel Facet in the Pleiotropic Activities of Snake Venom Phospholipases A2. [JOURNAL ARTICLE]
- PLoS One 2014; 9(12):e115428.
Phospholipases A2 represent the most abundant family of snake venom proteins. They manifest an array of biological activities, which is constantly expanding. We have recently shown that a protein bitanarin, isolated from the venom of the puff adder Bitis arietans and possessing high phospholipolytic activity, interacts with different types of nicotinic acetylcholine receptors and with the acetylcholine-binding protein. To check if this property is characteristic to all venom phospholipases A2, we have studied the capability of these enzymes from other snakes to block the responses of Lymnaea stagnalis neurons to acetylcholine or cytisine and to inhibit α-bungarotoxin binding to nicotinic acetylcholine receptors and acetylcholine-binding proteins. Here we present the evidence that phospholipases A2 from venoms of vipers Vipera ursinii and V. nikolskii, cobra Naja kaouthia, and krait Bungarus fasciatus from different snake families suppress the acetylcholine- or cytisine-elicited currents in L. stagnalis neurons and compete with α-bungarotoxin for binding to muscle- and neuronal α7-types of nicotinic acetylcholine receptor, as well as to acetylcholine-binding proteins. As the phospholipase A2 content in venoms is quite high, under some conditions the activity found may contribute to the deleterious venom effects. The results obtained suggest that the ability to interact with nicotinic acetylcholine receptors may be a general property of snake venom phospholipases A2, which add a new target to the numerous activities of these enzymes.
- Hydrogen Sulfide and Endothelium-Dependent Vasorelaxation. [REVIEW]
- Molecules 2014; 19(12):21183-21199.
In addition to nitric oxide and carbon monoxide, hydrogen sulfide (H2S), synthesized enzymatically from l-cysteine or l-homocysteine, is the third gasotransmitter in mammals. Endogenous H2S is involved in the regulation of many physiological processes, including vascular tone. Although initially it was suggested that in the vascular wall H2S is synthesized only by smooth muscle cells and relaxes them by activating ATP-sensitive potassium channels, more recent studies indicate that H2S is synthesized in endothelial cells as well. Endothelial H2S production is stimulated by many factors, including acetylcholine, shear stress, adipose tissue hormone leptin, estrogens and plant flavonoids. In some vascular preparations H2S plays a role of endothelium-derived hyperpolarizing factor by activating small and intermediate-conductance calcium-activated potassium channels. Endothelial H2S signaling is up-regulated in some pathologies, such as obesity and cerebral ischemia-reperfusion. In addition, H2S activates endothelial NO synthase and inhibits cGMP degradation by phosphodiesterase 5 thus potentiating the effect of NO-cGMP pathway. Moreover, H2S-derived polysulfides directly activate protein kinase G. Finally, H2S interacts with NO to form nitroxyl (HNO)-a potent vasorelaxant. H2S appears to play an important and multidimensional role in endothelium-dependent vasorelaxation.
- [Effect of manual acupuncture stimulation of "Baihui" (GV 20) and "Dazhui" (GV 14) on contents of 5-HT, dopamine and ACh and expression of 5-HT mRNA, DA mRNA and AChE mRNA in the hippocampus in methamphetamine addiction rats]. [English Abstract, Journal Article]
- Zhen Ci Yan Jiu 2014 Oct; 39(5):362-6.
To observe the effect of manual acupuncture stimulation on changes of hippocampal monoamine neurotransmitter levels and expression of 5-hydorxytryptamine (5-HT) mRNA, dopamine (DA) mRNA and acetylcholine esterase (AChE) mRNA in methamphetamine addiction rats, so as to explore its mechanism underlying improvement of drug addiction.SD rats were randomly divided into normal control, model and manual acupuncture groups (n=10 in each group). Drug addiction model was established by i.p. of methamphetamine (5 mg/kg), once a day for 15 days. Manual acupuncture stimu- lation was applied to "Baihui" (GV 20) and "Dazhui" (GV 14) once daily for 10 days. The contents of hippocampal 5-HT, DA, acetylcholine (ACh), AChE were measured by ELISA. The expressive Ilieels of hippocampal 5-HT mRNA, DA mRNA and AChE mRNA were determined by fluorescence quantitative RT-POR.In comparison with the normal control group, the con- tents of 5-HT, DA, ACh and AChE and the expression levels of 5-HT mRNA, DA mRNA and AChE mRNA were significantly increased in the model group (P<0.01, P<0.05). After acupuncture intervention, the levels of the above-mentioned 7 indexes were uniformly and significantly down-regulated in the manual acupuncture group (P<0.01, P<0.05).Manual acupuncture stimulation of GV 20 and GV 14 can adjust methamphetamine addiction-induced changes of some hippocampal monoa- mine neurotransmitters and expression levels of 5-HT, DA and AChE genes.
- Intramembrane aromatic interactions influence the lipid sensitivities of pentameric ligand-gated ion channels. [JOURNAL ARTICLE]
- J Biol Chem 2014 Dec 17.
Although the Torpedo nicotinic acetylcholine receptor (nAChR) reconstituted into phosphatidylcholine (PC) membranes lacking cholesterol and anionic lipids adopts a conformation where agonist binding is uncoupled from channel gating, the underlying mechanism remains to be defined. Here, we examine the mechanism behind lipid-dependent uncoupling by comparing the propensities of two prokaryotic homologs, GLIC and ELIC, to adopt a similar uncoupled conformation. Membrane-reconstituted GLIC and ELIC both exhibit folded structures in the minimal PC membranes that stabilize an uncoupled nAChR. GLIC, with a large number of aromatic interactions at the interface between the outermost transmembrane α-helix, M4, and the adjacent transmembrane α-helices, M1 and M3, retains the ability to flux cations in this uncoupling PC membrane environment. In contrast, ELIC, with a level of aromatic interactions intermediate between that of the nAChR and GLIC, does not undergo agonist-induced channel gating, even though it does not exhibit the expected biophysical characteristics of the uncoupled state. Engineering new aromatic interactions at the M4-M1/M3 interface to promote effective M4 interactions with M1/M3, however, increases the stability of the transmembrane domain to restore channel function. Our data provide direct evidence that M4 interactions with M1/M3 are modulated during lipid sensing. Aromatic residues strengthen M4 interactions with M1/M3 to reduce the sensitivities of pentameric ligand-gated ion channels to their surrounding membrane environment.
- B cells produce less IL-10, IL-6 and TNF-α in myasthenia gravis. [JOURNAL ARTICLE]
- Autoimmunity 2014 Dec 18.:1-7.
Abstract B cells from myasthenia gravis (MG) patients with autoantibodies (Aab) against acetylcholine receptor (AChR), muscle-specific kinase (MuSK) or with no detectable Aab were investigated as cytokine producing cells in this study. B cells were evaluated for memory phenotypes and expressions of IL-10, IL-6 and IL-12A. Induced productions of IL-10, IL-6, IL-12p40, TNF-α and LT from isolated B cells in vitro were measured by immunoassays. MG patients receiving immunosuppressive treatment had higher proportions of memory B cells compared with healthy controls and untreated patients. With CD40 stimulation MG patients produced significantly lower levels of IL-10, IL-6. With CD40 and B cell receptor stimulation of B cells, TNF-α production also decreased in addition to these cytokines. The lower levels of these cytokine productions were not related to treatment. Our results confirm a disturbance of B cell subpopulations in MG subgroups on immunosuppressive treatment. B cell derived IL-10, IL-6 and TNF-α are down-regulated in MG, irrespective of different antibody productions. Ineffective cytokine production by B cells may be a susceptibility factor in dysregulation of autoimmune Aab production.