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1.
Genet Mol Res ; 15(4)2016 Oct 17.
Article in English | MEDLINE | ID: mdl-27813610

ABSTRACT

Most taxa in the Bignoniaceae have 2n = 40, but the basal clade Jacarandeae has 2n = 36, suggesting that x = 18 is the ancestral basic number for the family. Variations in heterochromatin band patterns in genera that are numerically stable, such as Jacaranda, could facilitate our understanding of the chromosomal and karyotypic evolution of the family. We characterized heterochromatin distributions in six Jacaranda species using chromomycin A3 (CMA) and 4'6-diamidino-2-phenylindole (DAPI). All of them had 2n = 36, including first counts for Jacaranda bracteata Bureau & K. Schum., Jacaranda irwinii A.H. Gentry, Jacaranda jasminoides (Thunb.) Sandwith, and Jacaranda rugosa A.H. Gentry. Their karyotypes had four to eight terminal CMA+/DAPI- bands per monoploid set. In the section Monolobos, Jacaranda brasiliana (Lam.) Pers. had eight terminal bands and Jacaranda mimosifolia D. Don had four; in the section Dilobos, J. bracteata had six bands per monoploid set, with the other species having five. While three species in the section Dilobos had the same number of terminal bands, J. irwinii had two additional pericentromeric bands and a proximal heterozygotic band, and J. bracteata had two distended CMA bands. The consistent records of 2n = 36 in Jacaranda may represent a plesiomorphic condition for the Bignoniaceae; therefore, the family originated from an ancestor with x = 18. However, 2n = 36 may represent a derived condition, and the family could have had an ancestral basic number of x = 20 that is still conserved in most representatives of the family.


Subject(s)
Bignoniaceae/genetics , Biological Evolution , Chromosomes, Plant/genetics , Heterochromatin/genetics , Karyotype , Metaphase/genetics , Species Specificity
2.
Biochem Biophys Res Commun ; 386(1): 111-7, 2009 Aug 14.
Article in English | MEDLINE | ID: mdl-19501051

ABSTRACT

Potassium channels encoded by hERG (human ether-à-go-go-related gene) underlie the cardiac rapid delayed rectifier K+ current (IKr) and hERG mutations underpin clinically important repolarization disorders. Virtually all electrophysiological investigations of hERG mutations have studied exclusively the hERG1a isoform; however, recent evidence indicates that native IKr channels may be comprised of hERG1a together with the hERG1b variant, which has a shorter N-terminus. Here, for the first time, electrophysiological effects were studied of a gain-of-function hERG mutation (N588K; responsible for the 'SQT1' variant of the short QT syndrome) on current (I(hERG1a/1b)) carried by co-expressed hERG1a/1b channels. There were no significant effects of N588K on I(hERG1a/1b) activation or deactivation, but N588K I(hERG1a/1b) showed little inactivation up to highly positive voltages (< or = +80 mV), a more marked effect than seen for hERG1a expressed alone. I(hERG1a/1b) under action potential voltage-clamp, and the effects on this of the N588K mutation, also showed differences from those previously reported for hERG1a. The amplified attenuation of I(hERG) inactivation for the N588K mutation reported here indicates that the study of co-expressed hERG1a/1b channels should be considered when investigating clinically relevant hERG channel mutations, even if these reside outside of the N-terminus region.


Subject(s)
Arrhythmias, Cardiac/physiopathology , Ether-A-Go-Go Potassium Channels/physiology , Mutation , Arrhythmias, Cardiac/genetics , Cell Line , ERG1 Potassium Channel , Ether-A-Go-Go Potassium Channels/genetics , Humans
3.
Cardiovasc Res ; 67(3): 498-509, 2005 Aug 15.
Article in English | MEDLINE | ID: mdl-16039272

ABSTRACT

OBJECTIVE: Short QT syndrome (SQTS) is characterized by ventricular arrhythmias and sudden death. One form of SQTS is caused by mutation N588K in human ether-a-go-go-related gene (HERG). In this study we sought to determine the potential role of N588K in arrhythmias. METHODS: We measured the characteristics of HERG current generated by wild-type (WT) KCNH2 and the N588K mutant channel expressed in mammalian TSA201 cells. RESULTS: Whole-cell patch-clamp recordings of WT HERG currents showed the usual rapid onset of inactivation (rectification) at potentials more positive than +10 mV. In contrast, N588K currents rectified at potentials over +80 mV. Over the physiological range of potentials, N588K currents do not inactivate. During an action potential clamp, WT currents displayed a "hump" like waveform with slow activation kinetics and a rapid increase during phase 3 repolarization. In contrast, N588K currents were proportional to the amplitude of the action potential and displayed a dome-like configuration and a much larger current during the initial phases in the ventricle. Purkinje cell action potentials display a more negative phase 2 repolarization than the ventricle and elicited much smaller WT and N588K currents of similar amplitudes. CONCLUSIONS: Physiologically the N588K mutation abolishes rectification of HERG currents and specifically increases I(Kr) in the ventricle with minimal effects on the Purkinje fiber action potential duration. Such preferential prolongation may explain the separation of the T and U waves observed in the ECG of SQTS patients and lead to re-excitation of the ventricle endocardium.


Subject(s)
Death, Sudden, Cardiac/etiology , Ether-A-Go-Go Potassium Channels/genetics , Mutation , Myocytes, Cardiac/metabolism , Purkinje Fibers/metabolism , Ventricular Fibrillation/genetics , Action Potentials , Cell Line , ERG1 Potassium Channel , Ether-A-Go-Go Potassium Channels/metabolism , Humans , Ion Channel Gating , Mutagenesis, Site-Directed , Patch-Clamp Techniques , Potassium Channels, Voltage-Gated/genetics , Potassium Channels, Voltage-Gated/metabolism , Transfection/methods , Ventricular Fibrillation/metabolism
4.
Cardiovasc Res ; 65(1): 117-27, 2005 Jan 01.
Article in English | MEDLINE | ID: mdl-15621039

ABSTRACT

OBJECTIVE: To determine the presence and the potential contribution of neuronal sodium channels to dog cardiac function. METHODS: We used a combination of electrophysiological (patch clamp), RT-PCR, biochemical and immunohistochemical techniques to identify and localize neuronal Na(+) channels in dog heart and determine their potential contribution to the fast sodium current. RESULTS: In all cardiac tissues investigated, Na(v)1.1, Na(v)1.2 and Na(v)1.3 transcripts were detected. In immunoblots, we found Na(v)1.1 and Na(v)1.2 proteins in the ventricle (V) and in Purkinje fibers (PF). Na(v)1.3 immunoblots suggested strong proteolytic activity against this isoform in the heart. Na(v)1.6 was not found in any of the tissues tested. Confocal immunofluorescence on cardiac myocytes showed that Na(v)1.1 was predominantly localized at the intercalated disks in V and PF and around the nucleus (V). Na(v)1.2 was only present at the Z lines (V). Consistent with the immunoblot data, an intense but diffuse intracellular staining was observed for Na(v)1.3. Na(v)1.6 fluorescence staining was faint and diffuse. Surprisingly, immunoblots indicated the presence of two Na(v)beta 2 variants: a 42-kDa protein that co-localized with Na(v)1.2 at the Z lines in V and a 34-kDa protein that co-localized with Na(v)1.1 at the intercalated disks in PF. In agreement with the biochemical data, electrophysiological results suggest that neuronal sodium channels generate 10+/-5% and 22+/-5% of the peak sodium current in dog ventricle and Purkinje fibers, respectively. CONCLUSIONS: Our results suggest that neuronal NaChs are more abundant in Purkinje fibers than in ventricles, and this suggests a role for them in cardiac conduction.


Subject(s)
Myocytes, Cardiac/metabolism , Neurons/metabolism , Purkinje Fibers/metabolism , Sodium Channels/metabolism , Sodium-Potassium-Exchanging ATPase/metabolism , Animals , Dogs , Heart Ventricles , Immunoblotting , Microscopy, Confocal , Myocytes, Cardiac/chemistry , Patch-Clamp Techniques , Purkinje Fibers/chemistry , Reverse Transcriptase Polymerase Chain Reaction
5.
Acta Physiol (Oxf) ; 218(4): 265-275, 2016 12.
Article in English | MEDLINE | ID: mdl-27370818

ABSTRACT

AIM: Pathophysiological mechanisms of chronic visceral pain (CVP) are unknown. This study explores the association between the sympathetic system and bladder nociceptors activity by testing the effect of a prolonged adrenergic stimulation on transient receptor potential vanilloid 1 (TRPV1) activity and on urothelial adenosine triphosphate (ATP) release. METHODS: Female Wistar rats received saline, phenylephrine (PHE), PHE + silodosin, PHE + naftopidil or PHE + prazosin. TRPV1 knockout and wild-type mice received saline or PHE. Visceral pain behaviour tests were performed before and after treatment. Cystometry was performed, during saline and capsaicin infusion. Fos immunoreactivity was assessed in L6 spinal cord segment. Human urothelial ATP release induced by mechanical and thermal stimulation was evaluated. RESULTS: Subcutaneous, but not intrathecal, PHE administration induced pain, which was reversed by silodosin, a selective alpha 1A adrenoceptor antagonist, but not by naftopidil, a relatively selective antagonist for alpha 1D adrenoceptor. Silodosin also reversed PHE-induced bladder hyperactivity and L6 spinal cord Fos expression. Thus, in subsequent experiments, only silodosin was used. Wild-type, but not TRPV1 knockout, mice exhibited phenylephrine-induced pain. Capsaicin induced a greater increase in voiding contractions in PHE-treated rats than in control animals, and silodosin reversed this effect. When treated with PHE, ATP release from human urothelial cells was enhanced either by mechanical stimulation or by lowering the thermal threshold of urothelial TRPV1, which becomes abnormally responsive at body temperature. CONCLUSION: This study suggests that the activation of peripheral alpha 1A adrenoceptors induces CVP, probably through its interaction with TRPV1 and ATP release.


Subject(s)
Adenosine Triphosphate/metabolism , Receptors, Adrenergic, alpha-1/metabolism , TRPV Cation Channels/metabolism , Urinary Bladder/metabolism , Visceral Pain/metabolism , Animals , Disease Models, Animal , Female , Humans , Immunohistochemistry , Luminescent Measurements , Mice , Mice, Inbred C57BL , Mice, Knockout , Rats , Rats, Wistar , Urothelium/metabolism
6.
Cont Lens Anterior Eye ; 39(5): 397-9, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27503126

ABSTRACT

The absence of the eyeball can generate psychosocial and facial harmony changes, such as atrophy of the muscles around it. In these cases, the use of an orthostatic prosthesis with expanding function fosters distension of the tissues for subsequent rehabilitation. This technique consists of making individual ocular prostheses with gradual enlargement of size. The aim of this following clinical report was to describe the technique used in the standing prosthetic rehabilitation of a patient, 73 years old, who underwent enucleation of the right eye as a result of glaucoma. Clinical and laboratory procedures were performed such as impression, adjusting curvature of the sclera, centering the pupil area and processing in heat-cured acrylic resin three prostheses made according to the expansion of the anophthalmic cavity. At the end of treatment, there was a considerable increase of the cavity, allowing for volume replacement similar to that existing in the patient's contralateral orbit, thus generating a satisfactory facial harmony.


Subject(s)
Anophthalmos/rehabilitation , Eye, Artificial , Prosthesis Fitting/methods , Prosthesis Implantation/methods , Aged , Anophthalmos/diagnosis , Anophthalmos/surgery , Equipment Failure Analysis , Female , Humans , Prosthesis Design , Treatment Outcome
7.
Cardiovasc Res ; 28(12): 1794-802, 1994 Dec.
Article in English | MEDLINE | ID: mdl-7867032

ABSTRACT

OBJECTIVE: The objectives were (1) to develop a cellular model of simulated ischaemia and reperfusion in isolated ventricular myocytes; (2) to determine effects of simulated ischaemia and reperfusion on calcium current (ICa), transient inward current (ITI) and contraction; and (3) to determine whether pharmacological agents which alter intracellular sodium and calcium loading affect signs of calcium overload in reperfusion in this model. METHODS: Electrical activity was recorded with conventional and voltage clamp techniques. Cell shortening was measured with a video edge detector. Myocytes were equilibrated in Tyrode solution, exposed to simulated ischaemia (hypoxia, acidosis, lactate, hyperkalaemia, glucose-free) for 20 min, and reperfused with Tyrode solution. RESULTS: Ischaemia depolarised myocytes [-89(SEM 1) to -67(4) mV, p < 0.05], abbreviated action potential duration [APD90, 257(14) to 188(12) ms, p < 0.05], and abolished contractions. Contractions elicited by voltage clamp steps also were abolished in ischaemia; however, ICa decreased by only 51% [-0.98(0.08) to -0.50(0.06) nA, p < 0.05]. Signs of calcium overload, including aftercontractions, oscillatory afterpotentials, and ITI, occurred in 69% of myocytes in reperfusion. Upon reperfusion, both APD90 and ICa recovered slowly; however, contractions returned quickly and temporarily exceeded control. Amiloride during ischaemia and reperfusion lowered incidence of ITI in reperfusion, whereas nifedipine and lignocaine had no effect on ITI. CONCLUSIONS: This model of ischaemia and reperfusion in ventricular myocytes shows many features of multicellular preparations, such as membrane depolarisation and action potential duration shortening during ischaemia, and appearance of oscillatory afterpotentials upon reperfusion. Inhibition of contraction during ischaemia and recovery of contraction in reperfusion are independent of changes in APD90 or ICa. Induction of aftercontractions, oscillatory afterpotentials, and ITI in reperfusion is associated with reduced peak ICa. Amiloride most probably decreased signs of calcium overload in early reperfusion by inhibiting sodium loading via Na+/H+ exchange. Additionally, amiloride may inhibit ITI directly by blocking Na+/Ca2+ exchange.


Subject(s)
Disease Models, Animal , Myocardial Ischemia/pathology , Myocardial Reperfusion Injury/pathology , Myocardium/pathology , Action Potentials , Amiloride/pharmacology , Animals , Calcium-Transporting ATPases/drug effects , Calcium-Transporting ATPases/metabolism , Cell Size , Cells, Cultured , Guinea Pigs , Heart/physiopathology , Male , Myocardial Ischemia/physiopathology , Myocardial Reperfusion Injury/physiopathology , Myocardium/metabolism
8.
Cardiovasc Res ; 44(2): 356-69, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10690312

ABSTRACT

OBJECTIVE: Our goal was to identify the ATP-sensitive potassium (KATP) channels in cardiac Purkinje cells and to document the functional properties that might distinguish them from KATP channels in other parts of the heart. METHODS: Single Purkinje cells and ventricular myocytes were isolated from rabbit heart. Standard patch-clamp techniques were used to record action potential waveforms. and whole-cell and single-channel currents. RESULTS: The KATP channel opener levcromakalim (10 microM) caused marked shortening of the Purkinje cell action potential. Under whole-cell voltage-clamp, levcromakalim induced an outward current, which was blocked by glibenclamide (5 microM), in both Purkinje cells and ventricular myocytes. Metabolic poisoning of Purkinje cells with NaCN and 2-deoxyglucose caused a significant shortening of the action potential (control 376 +/- 51 ms; 6 min NaCN/2-deoxyglucose 153 +/- 21 ms). This effect was reversed with the application of glibenclamide. Inside-out membrane patches from Purkinje cells showed unitary current fluctuations which were inhibited by cytoplasmic ATP with an IC50 of 119 microM and a Hill coefficient of 2.1. This reflects approximately five-fold lower sensitivity to ATP inhibition than for KATP channels from ventricular myocytes under the same conditions. The slope conductance of Purkinje cell KATP channels, with symmetric, 140 mM K+, was 60.1 +/- 2.0 pS (mean +/- SEM). Single-channel fluctuations showed mean open and closed times of 3.6 +/- 1.5 ms and 0.41 +/- 0.2 ms, respectively, at -60 mV and approximately 21 degrees C. At positive potentials. KATP channels exhibited weak inward rectification that was dependent on the concentration of internal Mg2+. Computer simulations, based on the above results, predict significant shortening of the Purkinje cell action potential via activation of KATP channels in the range 1-5 mM cytoplasmic ATP. CONCLUSIONS: Purkinje cell KATP channels may represent a molecular isoform distinct from that present in ventricular myocytes. The presence of KATP channels in the Purkinje network suggests that they may have an important influence on cardiac rhythm and conduction during periods of ischemia.


Subject(s)
Action Potentials/drug effects , Adenosine Triphosphate/metabolism , Computer Simulation , Cromakalim/pharmacology , Potassium Channels/drug effects , Purkinje Fibers/metabolism , Adenosine Triphosphate/pharmacology , Animals , Arrhythmias, Cardiac/metabolism , Cell Separation , Deoxyglucose/pharmacology , Dose-Response Relationship, Drug , Glyburide/pharmacology , Heart Ventricles/drug effects , Heart Ventricles/metabolism , Ion Channel Gating/drug effects , Male , Patch-Clamp Techniques , Purkinje Fibers/drug effects , Rabbits , Sodium Cyanide/pharmacology
9.
Neuroscience ; 306: 74-90, 2015 Oct 15.
Article in English | MEDLINE | ID: mdl-26299340

ABSTRACT

Sodium-dependent high-affinity amino-acid transporters play crucial roles in terminating synaptic transmission in the central nervous system (CNS). However, there is lack of information about the mechanisms underlying the regulation of amino-acid transport by fast-acting neuromodulators, like ATP. Here, we investigated whether activation of the ATP-sensitive P2X7 receptor modulates Na(+)-dependent high-affinity γ-aminobutyric acid (GABA) and glutamate uptake into nerve terminals (synaptosomes) of the rat cerebral cortex. Radiolabeled neurotransmitter accumulation was evaluated by liquid scintillation spectrometry. The cell-permeant sodium-selective fluorescent indicator, SBFI-AM, was used to estimate Na(+) influx across plasma membrane. 2'(3')-O-(4-benzoylbenzoyl)ATP (BzATP, 3-300 µM), a prototypic P2X7 receptor agonist, concentration-dependently decreased [(3)H]GABA (14%) and [(14)C]glutamate (24%) uptake; BzATP decreased transport maximum velocity (Vmax) without affecting the Michaelis constant (Km) values. The selective P2X7 receptor antagonist, A-438079 (3 µM), prevented inhibition of [(3)H]GABA and [(14)C]glutamate uptake by BzATP (100 µM). The inhibitory effect of BzATP coincided with its ability to increase intracellular Na(+) and was mimicked by Na(+) ionophores, like gramicidin and monensin. Increases in intracellular Na(+) (with veratridine or ouabain) or substitution of extracellular Na(+) by N-methyl-D-glucamine (NMDG)(+) all decreased [(3)H]GABA and [(14)C]glutamate uptake and attenuated BzATP effects. Uptake inhibition by BzATP (100 µM) was also attenuated by calmidazolium, which selectively inhibits Na(+) currents through the P2X7 receptor pore. In conclusion, disruption of the Na(+) gradient by P2X7 receptor activation downmodulates high-affinity GABA and glutamate uptake into rat cortical synaptosomes. Interference with amino-acid transport efficacy may constitute a novel target for therapeutic management of cortical excitability.


Subject(s)
Amino Acid Transport Systems, Acidic/pharmacokinetics , Cerebral Cortex/metabolism , Glutamic Acid/pharmacokinetics , Receptors, Purinergic P2X7/metabolism , Synaptosomes/metabolism , gamma-Aminobutyric Acid/pharmacokinetics , Adenosine Triphosphate/analogs & derivatives , Adenosine Triphosphate/pharmacology , Amino Acid Transport Systems, Acidic/drug effects , Animals , Benzofurans/pharmacokinetics , Carbon Radioisotopes , Cerebral Cortex/diagnostic imaging , Cerebral Cortex/drug effects , Female , Male , Phthalic Acids/pharmacokinetics , Purinergic P2X Receptor Agonists/pharmacology , Purinergic P2X Receptor Antagonists/pharmacology , Pyridines/pharmacology , Radionuclide Imaging , Rats , Rats, Wistar , Sodium/metabolism , Synaptosomes/diagnostic imaging , Synaptosomes/drug effects , Tetrazoles/pharmacology , Tritium
10.
Cell Calcium ; 29(5): 289-97, 2001 May.
Article in English | MEDLINE | ID: mdl-11292386

ABSTRACT

We investigated action potentials and Ca(2+) transients in rabbit Purkinje myocytes using whole cell patch clamp recordings and a confocal microscope. Purkinje cells were loaded with 5 microM Fluo-3/AM for 30min. Action potentials were elicited by application of a stimulus delivered through the recording pipettes. When Purkinje cells were stimulated in 2.0mM Ca(2+), transverse XT line scans revealed a symmetrical 'U'-shaped Ca(2+) transient demonstrating that the transient was initiated at the cell periphery. When Purkinje cells were superfused with 1 microM isoprenaline, both early and delayed afterdepolarizations were induced. XT line scans of cells exhibiting early afterdepolarizations showed a second symmetrical 'U'-shaped transient. This Ca(2+) transient was initiated at the cell periphery suggesting reactivation of the Ca(2+) current. In contrast, in Purkinje cells exhibiting delayed afterdepolarizations and a corresponding transient inward current, XT line scans revealed a heterogenous rise in Ca(2+) at both peripheral and central regions of the cell. Immunofluorescence staining of Purkinje cells with an antibody to ryanodine receptors (RyRs) revealed that RyRs are located at regularly spaced intervals throughout the interior of Purkinje cells. These results suggest that, although RyRs are located throughout Purkinje cells, only peripheral RyRs are activated to produce transients, sparks and early afterdepolarizations. During delayed afterdepolarizations, we observed a heterogenous rise in Ca(2+) at both peripheral and central regions of the cell as well as large central increases in Ca(2+). Although the latter may result from central release, we cannot exclude the possibility that it reflects Ca(2+) diffusion from subsarcolemmal sites.


Subject(s)
Purkinje Cells/physiology , Ryanodine Receptor Calcium Release Channel/physiology , Action Potentials , Animals , Heart/physiology , Male , Microscopy, Confocal/methods , Purkinje Cells/metabolism , Rabbits , Ryanodine Receptor Calcium Release Channel/metabolism
11.
Neurosci Res ; 38(4): 385-95, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11164565

ABSTRACT

The regulation of the carrier-mediated gamma-aminobutyric acid (GABA) efflux was studied in isolated synaptic plasma membrane (SPM) vesicles, which are particularly useful to study neurotransmitter release without interference of the exocytotic machinery. We investigated the effect of micromolar intravesicular Ca(2+) on the GABA release from SPM vesicles under conditions of basal release (superfusion with 150 mM NaCl), homoexchange (superfusion with 500 microM GABA) and K(+) depolarization-induced release (superfusion with 150 mM KCl). We observed that, in the presence of intravesicular Ca(2+) (10 microM), the maximal velocity (J(max)) of K(+) depolarization-induced GABA release is decreased by about 64%, and this effect was abolished in the presence of the channel blocker, La(3+). In contrast, the other mechanisms were not significantly altered by these cations. In agreement with our earlier results, inhibition of GABA uptake by intravesicular Ca(2+) was also observed by determining the kinetic parameters (K(0.5) and J(max)) of influx into the SPM vesicles. Under these conditions, the J(max) of GABA uptake was 17.4 pmol/s per mg protein, whereas in control experiments (absence of Ca(2+)), this value achieved 25.5 pmol/s per mg protein. The inhibitory effect of Ca(2+) on translocation of GABA across SPM appears to be mediated by calcium/calmodulin activation of protein phosphatase 2B (calcineurin), since it was completely relieved by W7 (calmodulin antagonist) and by cyclosporin A (calcineurin inhibitor). These results show that the GABA transport system, operating either in forward or backward directions, requires phosphorylation of internally localized calcineurin-sensitive sites to achieve maximal net translocation velocity.


Subject(s)
Calcium Signaling/physiology , Calcium/metabolism , Carrier Proteins/metabolism , Intracellular Membranes/metabolism , Membrane Proteins/metabolism , Membrane Transport Proteins , Organic Anion Transporters , Synaptic Transmission/physiology , Synaptic Vesicles/metabolism , gamma-Aminobutyric Acid/metabolism , Animals , Calcineurin/drug effects , Calcineurin/metabolism , Calcium Chloride/pharmacology , Calcium Signaling/drug effects , Carrier Proteins/drug effects , GABA Plasma Membrane Transport Proteins , Intracellular Membranes/drug effects , Membrane Potentials/drug effects , Membrane Potentials/physiology , Membrane Proteins/drug effects , Phosphorylation/drug effects , Potassium/pharmacology , Sheep , Subcellular Fractions/drug effects , Subcellular Fractions/metabolism , Synaptic Transmission/drug effects , Synaptic Vesicles/drug effects
12.
J Inorg Biochem ; 97(1): 132-42, 2003 Sep 15.
Article in English | MEDLINE | ID: mdl-14507469

ABSTRACT

The gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in vertebrate CNS. At GABAergic synapses, a high-affinity transporter exists, which is responsible for GABA reuptake and release during neurotransmission. GABA transporter activity depends on the phosphorylation/dephosphorylation state, being modulated by Ca(2+)/calmodulin-dependent protein phosphatase 2B (calcineurin). Aluminium is known to interfere with the Ca(2+)/calmodulin signalling pathway. In this work, we investigate the action of aluminium on GABA translocation mediated by the high-affinity transporter, using synaptic plasma membrane (SPM) vesicles and synaptosomes isolated from brain cortex. Aluminium completely relieved Ca(2+) downregulation of GABA transporter, when mediating uptake or release. Accordingly, aluminium inhibited Ca(2+)/calmodulin-dependent calcineurin activity present in SPM, in a concentration-dependent manner. The deleterious action of aluminium on the modulation of GABA transport was ascertained by comparative analysis of the aluminium effect on GABA uptake and release, under conditions favouring SPM dephosphorylation (presence of intracellular micromolar Ca(2+)) or phosphorylation (absence of Ca(2+) and/or presence of W-7, a selective calmodulin antagonist). In conclusion, aluminium-induced relief of Ca(2+) modulatory action on GABA transporter may contribute significantly to modify GABAergic signalling during neurotoxic events in response to aluminium exposure.


Subject(s)
Aluminum/pharmacology , Calcium/metabolism , Carrier Proteins/metabolism , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Membrane Proteins/metabolism , Membrane Transport Proteins , Organic Anion Transporters , Animals , Calcineurin/drug effects , Calcineurin/metabolism , Calcium/pharmacology , Carrier Proteins/drug effects , Dose-Response Relationship, Drug , GABA Plasma Membrane Transport Proteins , Membrane Potentials/drug effects , Membrane Potentials/physiology , Nerve Endings/drug effects , Nerve Endings/metabolism , Potassium/antagonists & inhibitors , Potassium/pharmacology , Rats , Sheep , Synaptic Vesicles/drug effects , Synaptic Vesicles/metabolism , Synaptosomes/drug effects , Synaptosomes/metabolism , Tritium , gamma-Aminobutyric Acid/metabolism
13.
Health Phys ; 60(1): 31-9, 1991 Jan.
Article in English | MEDLINE | ID: mdl-1983978

ABSTRACT

Fifty persons involved in the 137Cs accident in Goiânia showed symptoms of whole-body and local acute irradiation and also external or internal contamination mainly due to ingestion or absorption of 137Cs. Fourteen of the 50 developed severe bone marrow depression characterized by neutropenia and thrombocytopenia. Eight of these 14 received GM-CSF intravenously. None were submitted to bone marrow transplantation. Four of the 14 died due to hemorrhage and infection. For those with significant internal contamination evaluated by in-vitro and in-vivo assays, Prussian Blue was administered with doses ranging from 1.5 to 10 g d-1. Besides Prussian Blue, other measures were taken to increase decorporation of 137Cs, including administration of diuretics, water overload, and ergometric exercises. From 50 to 100 persons are being followed in a medical protocol.


Subject(s)
Accidents , Bone Marrow/radiation effects , Cesium Radioisotopes/adverse effects , Environmental Exposure , Radiation Injuries/etiology , Adolescent , Adult , Brazil , Child , Decontamination/methods , Female , Humans , Male , Middle Aged , Radiation Injuries/therapy , Radioisotope Teletherapy/instrumentation
14.
Acta Med Port ; 2(3): 138-41, 1989.
Article in Portuguese | MEDLINE | ID: mdl-2696328

ABSTRACT

Specific benign lesions may be suggested when appropriate c.t. findings are detected in the liver. Characteristic c.t. patterns which may contribute to the study of hepatic masses are described and the importance of their recognition to the differential diagnosis is referred.


Subject(s)
Liver Neoplasms/diagnostic imaging , Tomography, X-Ray Computed , Diagnosis, Differential , Humans , Liver Diseases/diagnostic imaging , Liver Diseases/pathology , Liver Neoplasms/pathology
15.
Microb Cell ; 1(9): 289-302, 2014 Aug 09.
Article in English | MEDLINE | ID: mdl-28357255

ABSTRACT

Alterations in the intracellular levels of calcium are a common response to cell death stimuli in animals and fungi and, particularly, in the Neurospora crassa response to staurosporine. We highlight the importance of the extracellular availability of Ca2+ for this response. Limitation of the ion in the culture medium further sensitizes cells to the drug and results in increased accumulation of reactive oxygen species (ROS). Conversely, an approximately 30-fold excess of external Ca2+ leads to increased drug tolerance and lower ROS generation. In line with this, distinct staurosporine-induced cytosolic Ca2+ signaling profiles were observed in the absence or presence of excessive external Ca2+. High-throughput RNA sequencing revealed that different concentrations of extracellular Ca2+ define distinct transcriptional programs. Our transcriptional profiling also pointed to two putative novel Ca2+-binding proteins, encoded by the NCU08524 and NCU06607 genes, and provides a reference dataset for future investigations on the role of Ca2+ in fungal biology.

16.
Br J Pharmacol ; 160(8): 2028-44, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20649599

ABSTRACT

BACKGROUND AND PURPOSE: The compound NS5806 increases the transient outward current (I(to)) in canine ventricular cardiomyocytes and slows current decay. In human and canine ventricle, I(to) is thought to be mediated by K(V)4.3 and various ancillary proteins, yet, the exact subunit composition of I(to) channels is still debated. Here we characterize the effect of NS5806 on heterologously expressed putative I(to) channel subunits and other potassium channels. EXPERIMENTAL APPROACH: Cloned K(V)4 channels were co-expressed with KChIP2, DPP6, DPP10, KCNE2, KCNE3 and K(V)1.4 in Xenopus laevis oocytes or CHO-K1 cells. KEY RESULTS: NS5806 increased K(V)4.3/KChIP2 peak current amplitudes with an EC(50) of 5.3 +/- 1.5microM and significantly slowed current decay. KCNE2, KCNE3, DPP6 and DPP10 modulated K(V)4.3 currents and the response to NS5806, but current decay was slowed only in complexes containing KChIP2. The effect of NS5806 on K(V)4.2 was similar to that on K(V)4.3, and current decay was only slowed in presence of KChIP2. However, for K(V)4.1, the slowing of current decay by NS5806 was independent of KChIP2. K(V)1.4 was strongly inhibited by 10 microM NS5806 and K(V)1.5 was inhibited to a smaller extent. Effects of NS5806 on kinetics of currents generated by K(V)4.3/KChIP2/DPP6 with K(V)1.4 in oocytes could reproduce those on cardiac I(to) in canine ventricular myocytes. K(V)7.1, K(V)11.1 and K(ir)2 currents were unaffected by NS5806. CONCLUSION AND IMPLICATIONS: NS5806 modulated K(V)4 channel gating depending on the presence of KChIP2, suggesting that NS5806 can potentially be used to address the molecular composition as well as the physiological role of cardiac I(to).


Subject(s)
Ion Channel Gating/drug effects , Kv Channel-Interacting Proteins/metabolism , Phenylurea Compounds/pharmacology , Potassium/metabolism , Shal Potassium Channels/drug effects , Tetrazoles/pharmacology , Animals , CHO Cells , Cloning, Molecular , Cricetinae , Cricetulus , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Humans , Kinetics , Kv Channel-Interacting Proteins/genetics , Kv1.4 Potassium Channel/metabolism , Membrane Potentials , Nerve Tissue Proteins/metabolism , Potassium Channels/metabolism , Potassium Channels, Voltage-Gated/metabolism , Shal Potassium Channels/genetics , Shal Potassium Channels/metabolism , Transfection , Xenopus laevis
17.
Rev. bras. plantas med ; 16(3,supl.1): 685-692, 2014. tab
Article in Portuguese | LILACS | ID: lil-727196

ABSTRACT

O bioma Caatinga apresenta diversas espécies vegetais amplamente empregadas pelas populações rurais, especialmente na fitoterapia, abrangendo diversos usos no tratamento de determinadas enfermidades. As plantas espontâneas, apesar de serem entendidas como espécies daninhas ou invasoras, concomitantemente apresentam propriedades fitoquímicas que podem ser aproveitadas no âmbito medicinal. Nesta concepção, o referente trabalho tem como objetivo identificar espécies vegetais nativas da Caatinga, assim como plantas espontâneas, empregadas na medicina popular através de estudo etnobotânico desenvolvido na zona rural do município de Serra da Raiz, Agreste da Paraíba, Nordeste do Brasil. O levantamento das plantas de uso fitoterápico foi estabelecido através de questionamentos e entrevistas semiestruturadas com 57 famílias da região. Foram coletadas informações referentes a 55 espécies vegetais e seus empregos terapêuticos, destacando-se entre elas: Myracrodruom urundeuva Allemão (Aroeira), Genipa americana L. (Jenipapo), Solanum paniculatum L. (Jurubeba) e Anadenanthera colubrina (Vell.) Brenan (Angico) por serem amplamente utilizadas no tratamento de diversas enfermidades pelos moradores locais.


The Brazilian Caatinga has several plant species widely used by rural populations, especially in phytotherapy, covering many uses in the treatment of diseases. The spontaneous plants, although regarded as invasive plants or weeds, present phytochemical properties that can be exploited in medicine. This study aims to identify native plant species of the Caatinga and spontaneous plants used in medicine through an ethnobotanical study developed in the municipality of Serra da Raiz, Agreste area of the state of Paraíba, Brazil. The survey of plants used in herbal medicine was established through the questioning of and semi-structured interviews with 57 families in the region. Information was record on 55 plant species and their therapeutic uses. The species most used in the treatment of various diseases were Myracrodruon urundeuva Allemão, Genipa americana L., Solanum paniculatum L. and Anadenanthera colubrina (Vell.) Brenan..


Subject(s)
Humans , Male , Female , Adult , Middle Aged , Ecosystem , Semi-Arid Zone , Plant Weeds/adverse effects , Phytotherapy , Plants, Medicinal/metabolism , Rural Areas , Ethnobotany/statistics & numerical data , Therapeutic Uses
18.
J Physiol Pharmacol ; 60(1): 23-41, 2009 Mar.
Article in English | MEDLINE | ID: mdl-19439805

ABSTRACT

The short QT syndrome (SQTS) is a cardiac repolarisation disorder characterised by abbreviated QT intervals on the electrocardiogram and by an increased risk of atrial and ventricular arrhythmias and sudden death. The SQT1 variant involves a gain-of-function mutation (N588K) that impairs inactivation of the hERG (human ether-a-go-go-related gene) potassium channel and, thereby, increases current mediated by the rapid delayed rectifier potassium current (I(Kr)) in the heart. Here, the action potential voltage clamp (AP clamp) technique was applied to Chinese Hamster Ovary cells expressing wild-type or N588K-hERG at 37 degrees C, to compare effects of the N588K mutation on hERG current (I(hERG)) during ventricular, atrial and Purkinje fibre APs. The N588K mutation altered the I(hERG) profile during each AP type; increased maximal repolarising current occurred earlier during AP repolarisation (with shifts of +60 mV, +30 mV and +15 mV respectively for ventricular, Purkinje fibre and atrial APs). Thus SQT1 may influence repolarising I(hERG) for each cell type, with AP clamp experiments and simulation data indicating the greatest effect during ventricular APs. Changes in the timing of outward I(hERG) transients elicited by premature stimuli following AP commands indicate that SQT1 may alter the protection that hERG provides cardiac tissue against premature arrhythmogenic stimuli.


Subject(s)
Action Potentials/genetics , Delayed Rectifier Potassium Channels/metabolism , Ether-A-Go-Go Potassium Channels/genetics , Animals , CHO Cells , Cricetinae , Cricetulus , ERG1 Potassium Channel , Electrocardiography , Electrophysiology , Heart Atria/metabolism , Heart Ventricles/metabolism , Humans , Mutagenesis, Site-Directed , Mutation , Patch-Clamp Techniques , Purkinje Fibers/metabolism
19.
Am J Physiol Heart Circ Physiol ; 295(1): H154-62, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18456729

ABSTRACT

A greater depression of the action potential (AP) of the ventricular epicardium (Epi) versus endocardium (Endo) is readily observed in experimental models of acute ischemia and Brugada syndrome. Endo and Epi differences in transient outward K(+) current and/or ATP-sensitive K(+) channel current are believed to contribute to the differential response. The present study tested the hypothesis that the greater sensitivity of Epi is due in part to its functionally distinct early fast Na(+) current (I(Na)). APs were recorded from isolated Epi and Endo tissue slices and coronary-perfused wedge preparations before and after exposures to elevated extracellular K(+) concentration ([K(+)](o); 6-12 mM). I(Na) was recorded from Epi and Endo myocytes using whole cell patch-clamp techniques. In tissue slices, increasing [K(+)](o) to 12 mM reduced V(max) to 51.1 +/- 5.3% and 26.8 +/- 9.6% of control in Endo (n = 9) and Epi (n = 14), respectively (P < 0.05). In wedge preparations (n = 12), the increase in [K(+)](o) caused selective depression of Epi APs and transmural conduction slowing and block. I(Na) density was not significantly different between Epi (n = 14) and Endo (n = 15) cells, but Epi cells displayed a more negative half-inactivation voltage [-83.6 +/- 0.1 and -75.5 +/- 0.3 mV for Epi (n = 16) and Endo (n = 16), respectively, P < 0.05]. Our data suggest that reduced I(Na) availability in ventricular Epi may contribute to its greater sensitivity to electrical depression and thus may contribute to the R-ST segment changes observed under a variety of clinical conditions including acute myocardial ischemia, severe hyperkalemia, and Brugada syndrome.


Subject(s)
Endocardium/metabolism , Myocytes, Cardiac/metabolism , Pericardium/metabolism , Sodium Channels/metabolism , Sodium/metabolism , Action Potentials , Animals , Arrhythmias, Cardiac/metabolism , Arrhythmias, Cardiac/physiopathology , Dogs , Electrocardiography , Endocardium/physiopathology , Female , Heart Ventricles/metabolism , In Vitro Techniques , Male , Patch-Clamp Techniques , Pericardium/physiopathology , Potassium/metabolism , Time Factors
20.
Am J Physiol ; 269(1 Pt 2): H121-9, 1995 Jul.
Article in English | MEDLINE | ID: mdl-7631839

ABSTRACT

Effects of adenosine (ADN) on cardiac cellular electrical and contractile activity were determined during ischemia and reperfusion. Electrical activity was recorded with conventional and voltage-clamp techniques. Contractions were monitored with a video edge detector. Myocytes were exposed to simulated ischemia (20 min), in the presence or absence of ADN (1-50 microM), and reperfused with Tyrode solution. ADN had no effects under control conditions. However, action potential abbreviation during ischemia was greater in the presence of ADN than for control, and recovery was delayed. In ischemia, Ca2+ current declined equally, and contractions were abolished in control and ADN-treated myocytes. In early reperfusion, oscillatory afterpotentials (OAP), transient inward current (ITI) and aftercontractions appeared, and contractions increased above preischemic levels. ADN abolished contractile overshoot and reduced incidence of OAP, ITI, and aftercontractions from 78 to 37.5%. The effects of exogenous ADN were inhibited by ADN A1-receptor blockade. Inhibition of endogenous ADN by 8-phenyltheophylline only increased incidence of ITI. Thus exogenous ADN in ischemia may protect the myocardium in reperfusion via A1 receptors.


Subject(s)
Adenosine/pharmacology , Myocardial Ischemia/physiopathology , Myocardial Reperfusion , Ventricular Function/drug effects , Animals , Calcium/physiology , Diastole , Electrophysiology , Guinea Pigs , Male , Myocardial Contraction , Myocardium/pathology
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