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A Ylihankala - One of the best experts on this subject based on the ideXlab platform.
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ecg t Wave Amplitude changes during thiopentone induction with or without alfentanil
Acta Anaesthesiologica Scandinavica, 1995Co-Authors: P Annila, Leena Lindgren, P Loula, P Dunkel, I Annila, A YlihankalaAbstract:The T-Wave Amplitude of ECG is thought to reflect the sympathetic tone of the heart but anaesthesia studies on this topic are rare. Haemodynamic and ECG T-Wave Amplitude changes were studied during induction of anaesthesia in 24 ASA I-II patients. Twelve patients were given alfentanil 30 μg kg -1 at induction while physiologic saline was given to the rest (control). Thiopentone was then administered at the rate of 5 mg s -1 until eyelash reflex disappeared. Vecuronium 0.1 mg kg -1 was given thereafter. No anticholinergics were used. The lungs were ventilated with 40% oxygen in air. Haemodynamic parametres and T-Wave Amplitude were measured before induction, before intubation, 30 s, 3 min and 5 min after intubation. A significantly higher amount of thiopentone was needed to abolish the eyelash reflex in the control group than in the alfentanil group (P<0.001). There were no changes in heart rate (HR) in the alfentanil group during the trial. Systolic and diastolic arterial pressurcs (SAP and DAP) were continuously below the preinduction levels in the alfentanil group. After baseline HR, SAP and DAP were significantly higher in the control group than in the alfentanil group at each data point. T-Wave Amplitude flattened significantly (P<0.001) after intubation in the control group while no significant changes were seen in the alfentanil group. T-Wave flattening correlated to the increases in HR (P<0.01) and SAP (Pw0.01). Three control patients with flattened T-Wave had a transient bigeminia period after intubation. It is concluded that ECG T-Wave Amplitude flattening was associated with pressure and heart rate response to laryngoscopy and intubation. Alfentanil blunted these responses and presented T-Wave changes after intubation
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the effect of skin incision followed by alfentanil on catecholamine levels and on the t Wave Amplitude of ecg during isoflurane anaesthesia
Journal of Clinical Monitoring and Computing, 1995Co-Authors: P Annila, Leena Lindgren, P Loula, Mika Scheinin, A YlihankalaAbstract:Haemodynamic, ECG T-Wave Amplitude and plasma potassium changes and plasma catecholamine responses to skin incision followed by alfentanil were studied in 24 ASA I patients. Propofol and vecuronium were used without anticholinergics for induction of anaesthesia followed by isoflurane in 02/air. End-tidal isoflurane concentration was kept constant (0.7%) for 30 min before the skin incision. Five min after the skin incision alfentanil 30 #g kg -1 was given. Blood samples for catecholamines and plasma potassium concentrations were drawn from right ventricle of the heart one minute before and after the skin incision and two minutes after alfentanil. Heart rate, systolic and diastolic arterial pressures increased after the skin incision (P < 0.001), and decreased after alfentanil (P < 0.001). Plasma adrenaline and noradrenaline concentrations increased slightly after the skin incision (P < 0.05 and P < 0.01, respectively). Noradrenaline levels continued to increase after alfentanil (P < 0.001) despite totally abolished haemodynamic responses to the skin incision. ECG T-Wave Amplitude changes, measured as R/T ratio, did not correlate to the changes in plasma catecholamine levels: both rapid increases and decreases in R/T ratio were seen. No plasma potassium changes were seen during the trial. T-Wave changes, occurring in seconds after the skin incision, are probably produced by a direct catecholamine release from cardiac sympathetic nerve endings.
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the effect of atropine on the t Wave Amplitude of ecg during isoflurane anaesthesia
Journal of Clinical Monitoring and Computing, 1994Co-Authors: P Annila, A Ylihankala, Leena LindgrenAbstract:The effect of bolus dose of atropine (20 μg kg−1) on the R/T-Wave Amplitude ratio of electrocardiogram was studied in 12 patients during isoflurane anaesthesia at electroencephalogram burst suppression level (mean ET of isoflurane 1.8 vol-%). The Amplitude ratio was measured before, 1, 2, 5 and 10 min after atropine. Change was measured as decibels and 95% confidence intervals were calculated. The Amplitude of T-Wave flattened significantly after atropine. It is concluded, that the ECG T-Wave Amplitude reflects the balance of sympathetic and parasympathetic nervous activity during isoflurane anaesthesia. The use of the decibel transformation and confidence intervals seems to be a relevant method to interpret changes in physiologic measures during anaesthesia.
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effect of atropine on the qt interval and t Wave Amplitude in healthy volunteers
BJA: British Journal of Anaesthesia, 1993Co-Authors: P Annila, A Ylihankala, Leena LindgrenAbstract:Prolongation of the QT interval of the ECG represents an imbalance in cardiac autonomic function and may predict cardiac arrhythmia. Vagal activity protects against prolongation of the QT interval which may be associated with flattening of the T-Wave of the ECG. The changes in QT interval, T-Wave Amplitude and respiratory sinus arrhythmia (RSA) were studied after i.v. administration of atropine 20 µg kg−1 or placebo to 10 healthy volunteers in a cross-over study. After atropine, a decrease in RSA occurred in all volunteers, but remained at baseline values after placebo. Corrected QT interval (QTc) increased from 410 (20) ms to 454 (11) ms (P
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changes in the t Wave Amplitude of ecg during isoflurane anaesthesia
Acta Anaesthesiologica Scandinavica, 1993Co-Authors: P Annila, V Jantti, Leena Lindgren, A YlihankalaAbstract:R/T-Wave Amplitude ratio of electrocardiogram (ECG), heart rate (HR) and systolic arterial pressure (SAP) were recorded in 15 patients awake, at 1 minimal alveolar concentration of isoflurane before and during surgery, and in deep anaesthesia (electroencephalogram burst suppression) during surgery. R/T-Wave Amplitude ratio and HR were sensitive to both surgery and changes in the level of isoflurane anaesthesia; induction of anaesthesia, skin incision and the rapid increase in the concentration of isoflurane all significantly decreased the T-Wave Amplitude, without influence on the R-Wave. Changes in the T-Wave Amplitude correlated directly to HR. SAP increased at skin incision and decreased when the anaesthesia was deepened. The authors conclude that the R/T-Wave Amplitude ratio of ECG provides a reliable method for monitoring the sympathetic tone during isoflurane anaesthesia.
P Annila - One of the best experts on this subject based on the ideXlab platform.
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ecg t Wave Amplitude changes during thiopentone induction with or without alfentanil
Acta Anaesthesiologica Scandinavica, 1995Co-Authors: P Annila, Leena Lindgren, P Loula, P Dunkel, I Annila, A YlihankalaAbstract:The T-Wave Amplitude of ECG is thought to reflect the sympathetic tone of the heart but anaesthesia studies on this topic are rare. Haemodynamic and ECG T-Wave Amplitude changes were studied during induction of anaesthesia in 24 ASA I-II patients. Twelve patients were given alfentanil 30 μg kg -1 at induction while physiologic saline was given to the rest (control). Thiopentone was then administered at the rate of 5 mg s -1 until eyelash reflex disappeared. Vecuronium 0.1 mg kg -1 was given thereafter. No anticholinergics were used. The lungs were ventilated with 40% oxygen in air. Haemodynamic parametres and T-Wave Amplitude were measured before induction, before intubation, 30 s, 3 min and 5 min after intubation. A significantly higher amount of thiopentone was needed to abolish the eyelash reflex in the control group than in the alfentanil group (P<0.001). There were no changes in heart rate (HR) in the alfentanil group during the trial. Systolic and diastolic arterial pressurcs (SAP and DAP) were continuously below the preinduction levels in the alfentanil group. After baseline HR, SAP and DAP were significantly higher in the control group than in the alfentanil group at each data point. T-Wave Amplitude flattened significantly (P<0.001) after intubation in the control group while no significant changes were seen in the alfentanil group. T-Wave flattening correlated to the increases in HR (P<0.01) and SAP (Pw0.01). Three control patients with flattened T-Wave had a transient bigeminia period after intubation. It is concluded that ECG T-Wave Amplitude flattening was associated with pressure and heart rate response to laryngoscopy and intubation. Alfentanil blunted these responses and presented T-Wave changes after intubation
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the effect of skin incision followed by alfentanil on catecholamine levels and on the t Wave Amplitude of ecg during isoflurane anaesthesia
Journal of Clinical Monitoring and Computing, 1995Co-Authors: P Annila, Leena Lindgren, P Loula, Mika Scheinin, A YlihankalaAbstract:Haemodynamic, ECG T-Wave Amplitude and plasma potassium changes and plasma catecholamine responses to skin incision followed by alfentanil were studied in 24 ASA I patients. Propofol and vecuronium were used without anticholinergics for induction of anaesthesia followed by isoflurane in 02/air. End-tidal isoflurane concentration was kept constant (0.7%) for 30 min before the skin incision. Five min after the skin incision alfentanil 30 #g kg -1 was given. Blood samples for catecholamines and plasma potassium concentrations were drawn from right ventricle of the heart one minute before and after the skin incision and two minutes after alfentanil. Heart rate, systolic and diastolic arterial pressures increased after the skin incision (P < 0.001), and decreased after alfentanil (P < 0.001). Plasma adrenaline and noradrenaline concentrations increased slightly after the skin incision (P < 0.05 and P < 0.01, respectively). Noradrenaline levels continued to increase after alfentanil (P < 0.001) despite totally abolished haemodynamic responses to the skin incision. ECG T-Wave Amplitude changes, measured as R/T ratio, did not correlate to the changes in plasma catecholamine levels: both rapid increases and decreases in R/T ratio were seen. No plasma potassium changes were seen during the trial. T-Wave changes, occurring in seconds after the skin incision, are probably produced by a direct catecholamine release from cardiac sympathetic nerve endings.
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the effect of atropine on the t Wave Amplitude of ecg during isoflurane anaesthesia
Journal of Clinical Monitoring and Computing, 1994Co-Authors: P Annila, A Ylihankala, Leena LindgrenAbstract:The effect of bolus dose of atropine (20 μg kg−1) on the R/T-Wave Amplitude ratio of electrocardiogram was studied in 12 patients during isoflurane anaesthesia at electroencephalogram burst suppression level (mean ET of isoflurane 1.8 vol-%). The Amplitude ratio was measured before, 1, 2, 5 and 10 min after atropine. Change was measured as decibels and 95% confidence intervals were calculated. The Amplitude of T-Wave flattened significantly after atropine. It is concluded, that the ECG T-Wave Amplitude reflects the balance of sympathetic and parasympathetic nervous activity during isoflurane anaesthesia. The use of the decibel transformation and confidence intervals seems to be a relevant method to interpret changes in physiologic measures during anaesthesia.
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effect of atropine on the qt interval and t Wave Amplitude in healthy volunteers
BJA: British Journal of Anaesthesia, 1993Co-Authors: P Annila, A Ylihankala, Leena LindgrenAbstract:Prolongation of the QT interval of the ECG represents an imbalance in cardiac autonomic function and may predict cardiac arrhythmia. Vagal activity protects against prolongation of the QT interval which may be associated with flattening of the T-Wave of the ECG. The changes in QT interval, T-Wave Amplitude and respiratory sinus arrhythmia (RSA) were studied after i.v. administration of atropine 20 µg kg−1 or placebo to 10 healthy volunteers in a cross-over study. After atropine, a decrease in RSA occurred in all volunteers, but remained at baseline values after placebo. Corrected QT interval (QTc) increased from 410 (20) ms to 454 (11) ms (P
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changes in the t Wave Amplitude of ecg during isoflurane anaesthesia
Acta Anaesthesiologica Scandinavica, 1993Co-Authors: P Annila, V Jantti, Leena Lindgren, A YlihankalaAbstract:R/T-Wave Amplitude ratio of electrocardiogram (ECG), heart rate (HR) and systolic arterial pressure (SAP) were recorded in 15 patients awake, at 1 minimal alveolar concentration of isoflurane before and during surgery, and in deep anaesthesia (electroencephalogram burst suppression) during surgery. R/T-Wave Amplitude ratio and HR were sensitive to both surgery and changes in the level of isoflurane anaesthesia; induction of anaesthesia, skin incision and the rapid increase in the concentration of isoflurane all significantly decreased the T-Wave Amplitude, without influence on the R-Wave. Changes in the T-Wave Amplitude correlated directly to HR. SAP increased at skin incision and decreased when the anaesthesia was deepened. The authors conclude that the R/T-Wave Amplitude ratio of ECG provides a reliable method for monitoring the sympathetic tone during isoflurane anaesthesia.
Leena Lindgren - One of the best experts on this subject based on the ideXlab platform.
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ecg t Wave Amplitude changes during thiopentone induction with or without alfentanil
Acta Anaesthesiologica Scandinavica, 1995Co-Authors: P Annila, Leena Lindgren, P Loula, P Dunkel, I Annila, A YlihankalaAbstract:The T-Wave Amplitude of ECG is thought to reflect the sympathetic tone of the heart but anaesthesia studies on this topic are rare. Haemodynamic and ECG T-Wave Amplitude changes were studied during induction of anaesthesia in 24 ASA I-II patients. Twelve patients were given alfentanil 30 μg kg -1 at induction while physiologic saline was given to the rest (control). Thiopentone was then administered at the rate of 5 mg s -1 until eyelash reflex disappeared. Vecuronium 0.1 mg kg -1 was given thereafter. No anticholinergics were used. The lungs were ventilated with 40% oxygen in air. Haemodynamic parametres and T-Wave Amplitude were measured before induction, before intubation, 30 s, 3 min and 5 min after intubation. A significantly higher amount of thiopentone was needed to abolish the eyelash reflex in the control group than in the alfentanil group (P<0.001). There were no changes in heart rate (HR) in the alfentanil group during the trial. Systolic and diastolic arterial pressurcs (SAP and DAP) were continuously below the preinduction levels in the alfentanil group. After baseline HR, SAP and DAP were significantly higher in the control group than in the alfentanil group at each data point. T-Wave Amplitude flattened significantly (P<0.001) after intubation in the control group while no significant changes were seen in the alfentanil group. T-Wave flattening correlated to the increases in HR (P<0.01) and SAP (Pw0.01). Three control patients with flattened T-Wave had a transient bigeminia period after intubation. It is concluded that ECG T-Wave Amplitude flattening was associated with pressure and heart rate response to laryngoscopy and intubation. Alfentanil blunted these responses and presented T-Wave changes after intubation
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the effect of skin incision followed by alfentanil on catecholamine levels and on the t Wave Amplitude of ecg during isoflurane anaesthesia
Journal of Clinical Monitoring and Computing, 1995Co-Authors: P Annila, Leena Lindgren, P Loula, Mika Scheinin, A YlihankalaAbstract:Haemodynamic, ECG T-Wave Amplitude and plasma potassium changes and plasma catecholamine responses to skin incision followed by alfentanil were studied in 24 ASA I patients. Propofol and vecuronium were used without anticholinergics for induction of anaesthesia followed by isoflurane in 02/air. End-tidal isoflurane concentration was kept constant (0.7%) for 30 min before the skin incision. Five min after the skin incision alfentanil 30 #g kg -1 was given. Blood samples for catecholamines and plasma potassium concentrations were drawn from right ventricle of the heart one minute before and after the skin incision and two minutes after alfentanil. Heart rate, systolic and diastolic arterial pressures increased after the skin incision (P < 0.001), and decreased after alfentanil (P < 0.001). Plasma adrenaline and noradrenaline concentrations increased slightly after the skin incision (P < 0.05 and P < 0.01, respectively). Noradrenaline levels continued to increase after alfentanil (P < 0.001) despite totally abolished haemodynamic responses to the skin incision. ECG T-Wave Amplitude changes, measured as R/T ratio, did not correlate to the changes in plasma catecholamine levels: both rapid increases and decreases in R/T ratio were seen. No plasma potassium changes were seen during the trial. T-Wave changes, occurring in seconds after the skin incision, are probably produced by a direct catecholamine release from cardiac sympathetic nerve endings.
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the effect of atropine on the t Wave Amplitude of ecg during isoflurane anaesthesia
Journal of Clinical Monitoring and Computing, 1994Co-Authors: P Annila, A Ylihankala, Leena LindgrenAbstract:The effect of bolus dose of atropine (20 μg kg−1) on the R/T-Wave Amplitude ratio of electrocardiogram was studied in 12 patients during isoflurane anaesthesia at electroencephalogram burst suppression level (mean ET of isoflurane 1.8 vol-%). The Amplitude ratio was measured before, 1, 2, 5 and 10 min after atropine. Change was measured as decibels and 95% confidence intervals were calculated. The Amplitude of T-Wave flattened significantly after atropine. It is concluded, that the ECG T-Wave Amplitude reflects the balance of sympathetic and parasympathetic nervous activity during isoflurane anaesthesia. The use of the decibel transformation and confidence intervals seems to be a relevant method to interpret changes in physiologic measures during anaesthesia.
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effect of atropine on the qt interval and t Wave Amplitude in healthy volunteers
BJA: British Journal of Anaesthesia, 1993Co-Authors: P Annila, A Ylihankala, Leena LindgrenAbstract:Prolongation of the QT interval of the ECG represents an imbalance in cardiac autonomic function and may predict cardiac arrhythmia. Vagal activity protects against prolongation of the QT interval which may be associated with flattening of the T-Wave of the ECG. The changes in QT interval, T-Wave Amplitude and respiratory sinus arrhythmia (RSA) were studied after i.v. administration of atropine 20 µg kg−1 or placebo to 10 healthy volunteers in a cross-over study. After atropine, a decrease in RSA occurred in all volunteers, but remained at baseline values after placebo. Corrected QT interval (QTc) increased from 410 (20) ms to 454 (11) ms (P
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changes in the t Wave Amplitude of ecg during isoflurane anaesthesia
Acta Anaesthesiologica Scandinavica, 1993Co-Authors: P Annila, V Jantti, Leena Lindgren, A YlihankalaAbstract:R/T-Wave Amplitude ratio of electrocardiogram (ECG), heart rate (HR) and systolic arterial pressure (SAP) were recorded in 15 patients awake, at 1 minimal alveolar concentration of isoflurane before and during surgery, and in deep anaesthesia (electroencephalogram burst suppression) during surgery. R/T-Wave Amplitude ratio and HR were sensitive to both surgery and changes in the level of isoflurane anaesthesia; induction of anaesthesia, skin incision and the rapid increase in the concentration of isoflurane all significantly decreased the T-Wave Amplitude, without influence on the R-Wave. Changes in the T-Wave Amplitude correlated directly to HR. SAP increased at skin incision and decreased when the anaesthesia was deepened. The authors conclude that the R/T-Wave Amplitude ratio of ECG provides a reliable method for monitoring the sympathetic tone during isoflurane anaesthesia.
Karim Bendjelid - One of the best experts on this subject based on the ideXlab platform.
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Respiratory change in ECG-Wave Amplitude is a reliable parameter to estimate intravascular volume status
Journal of Clinical Monitoring and Computing, 2013Co-Authors: Raphaël Giraud, Nils Siegenthaler, Jacques-a Romand, Denis R. Morel, Laurent Brochard, Karim BendjelidAbstract:Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The “Brody effect”, a theoretical analysis of left ventricular (LV) chamber size influence on QRS-Wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-Wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-Wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-Wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax − ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both
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respiratory change in ecg Wave Amplitude is a reliable parameter to estimate intravascular volume status
Journal of Clinical Monitoring and Computing, 2013Co-Authors: Raphaël Giraud, Nils Siegenthaler, Karim Bendjelid, Denis R. Morel, Laurent Brochard, Jacquesandre RomandAbstract:Electrocardiogram (ECG) is a standard type of monitoring in intensive care medicine. Several studies suggest that changes in ECG morphology may reflect changes in volume status. The "Brody effect", a theoretical analysis of left ventricular (LV) chamber size influence on QRS-Wave Amplitude, is the key element of this phenomenon. It is characterised by an increase in QRS-Wave Amplitude that is induced by an increase in ventricular preload. This study investigated the influence of changes in intravascular volume status on respiratory variations of QRS-Wave Amplitudes (ΔECG) compared with respiratory pulse pressure variations (ΔPP), considered as a reference standard. In 17 pigs, ECG and arterial pressure were recorded. QRS-Wave Amplitude was measured from the Biopac recording to ensure that in all animals ECG electrodes were always at the same location. Maximal QRS Amplitude (ECGmax) and minimal QRS Amplitude (ECGmin) were determined over one respiratory cycle. ΔECG was calculated as 100 × [(ECGmax - ECGmin)/(ECGmax + ECGmin)/2]. ΔECG and ΔPP were simultaneously recorded. Measurements were performed at different time points: during normovolemic conditions, after haemorrhage (25 mL/kg), and following re-transfusion (25 mL/kg) with constant tidal volume (10 mL/kg) and respiration rate (15 breath/min). At baseline, ΔPP and ΔECG were both <12 %. ΔPP were significantly correlated with ΔECG (r(2) = 0.89, p < 0.001). Volume loss induced by haemorrhage increased significantly ΔPP and ΔECG. Moreover, during this state, ΔPP were significantly correlated with ΔECG (r(2) = 0.86, p < 0.001). Re-transfusion significantly decreased ΔPP and ΔECG, and ΔPP were significantly correlated with ΔECG (r(2) = 0.90, p < 0.001). The observed correlations between ΔPP and ΔECG at each time point of the study suggest that ΔECG is a reliable parameter to estimate the changes in intravascular volume status and provide experimental confirmation of the "Brody effect."
Siarhei A Siapich - One of the best experts on this subject based on the ideXlab platform.
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effects of quensyl on the erg a Wave Amplitude from the isolated superfused vertebrate retina
Acta Ophthalmologica, 2013Co-Authors: Siarhei A Siapich, A Goebel, Peter WalterAbstract:Purpose Long-term therapy with quensyl is known to cause neurodegenerative changes in the retina. In our present research we study acute toxic effects of quensyl on the a-Wave response of electroretinogram (ERG) of isolated superfused bovine retinas. Methods Isolated bovine retinae were mounted in a temperature-controlled recording chamber. After light stimulation electric field potentials were recorded as a transretinal potential using Ag/AgCl-electrodes. Isolated bovine retinas were perfused with phosphate buffered saline (PBS) containing 1mM L-aspartate to block further synaptic transmission in order to record the effects of quensyl on photoreceptors. We tested the low and high light intensities of 100 mlux and 10 lux. After reaching a stable ERG Amplitude, quensyl (190 µM, 570 µM or 1,9 mM) was added to the perfusing solution. After 90 min quensyl was washed out for 90 min with PBS containing 1mM L-aspartate. Changes in a-Wave Amplitude were calculated and plotted. Results 190 µM quensyl showed a 1,3 fold stimulation of the a-Wave Amplitude at 100 mlux, the effect at 10 lux was not significant. 570 µM quensyl reduced the a-Wave Amplitude by 3-folds independent of light-intensity. The inhibition was good reversible by washing with PBS containing 1mM L-aspartate only at low light intensity (2 folds), there was almost no recovery at 10 lux. 1,9 mM quensyl showed a massive depression of a-Wave Amplitude (6 to 7 folds) and no wash out effect over 90 minutes at both light intensities. Conclusion Quensyl has a toxic effect on photoreceptors, even with slight increase of concentration showing a huge progression of inhibition and reduction of recovery. An exact dosage of quensyl is of great importance to avoid an irreversible neuronal damage.
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effect of zncl 2 and chelation of zinc ions by n n diethyldithiocarbamate dedtc on the erg b Wave Amplitude from the isolated superfused vertebrate retina
Investigative Ophthalmology & Visual Science, 2010Co-Authors: Siarhei A Siapich, Walid Albanna, Jurgen Hescheler, Matthias Luke, Heiko Wrubel, Maged Alnawaiseh, Marco Weiergraber, Toni SchneiderAbstract:Purpose: NiCl 2 (15 µM) enhances the ERG b-Wave Amplitude of vertebrate retina, up to 1.5-fold by blocking E/R-type voltage-gated Ca 2+ channels, which is mediated by blocking the release of GABA onto ionotropic GABA-A and GABA-C receptors. In vivo, it is likely that zinc, rather than nickel ions, may be involved in the modulation of retinal signalling. Therefore, we tested the effect of both, ZnCl 2 (10 to 500 µM) and DEDTC (100 to 500 µM), which chelates zinc ions for the capacity to influence the ERG b-Wave Amplitude. Methods: Transretinal potentials from the isolated bovine retina were recorded as electroretinograms and Ca 2+ inward currents by patch-clamp recordings of stably Ca v 2.3 transfected HEK-293 cells, yielding an IC 50 value of 5.3 µM for ZnCl 2 . Results: ZnCl 2 (10–15 µM) increased the b-Wave Amplitude by 1.52-fold ± 0.12 (n = 6 retinas), which was partially reversible upon washout. The same 1.5-fold stimulation of the b-Wave Amplitude was reported recently for 15 µM NiCl 2 . The superfusion of isolated retinas by DEDTC (100 µM) caused a transient decrease of the ERG b-Wave Amplitude (0.75-fold ± 0.06; n = 4), suggesting that the cosecretion of Zn 2+ ions may occur under scotopic conditions. Conclusion: The stimulatory effect of ZnCl 2 on the ERG b-Wave Amplitude resembles the stimulatory effect of NiCl 2 and may be mediated rather by the NiCl 2 -sensitive, Ca v 2.3 E-/R-type voltage-gated Ca 2+ channels than by NiCl 2 -sensitive T-type channels.
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effect of zncl2 and chelation of zinc ions by n n diethyldithiocarbamate dedtc on the erg b Wave Amplitude from the isolated superfused vertebrate retina
Current Eye Research, 2010Co-Authors: Siarhei A Siapich, Walid Albanna, Jurgen Hescheler, Matthias Luke, Heiko Wrubel, Maged Alnawaiseh, Marco Weiergraber, Toni SchneiderAbstract:Purpose: NiCl2 (15 µM) enhances the ERG b-Wave Amplitude of vertebrate retina, up to 1.5-fold by blocking E/R-type voltage-gated Ca2+ channels, which is mediated by blocking the release of GABA onto ionotropic GABA-A and GABA-C receptors. In vivo, it is likely that zinc, rather than nickel ions, may be involved in the modulation of retinal signalling. Therefore, we tested the effect of both, ZnCl2 (10 to 500 µM) and DEDTC (100 to 500 µM), which chelates zinc ions for the capacity to influence the ERG b-Wave Amplitude.Methods: Transretinal potentials from the isolated bovine retina were recorded as electroretinograms and Ca2+ inward currents by patch-clamp recordings of stably Cav2.3 transfected HEK-293 cells, yielding an IC50 value of 5.3 µM for ZnCl2.Results: ZnCl2 (10–15 µM) increased the b-Wave Amplitude by 1.52-fold ± 0.12 (n = 6 retinas), which was partially reversible upon washout. The same 1.5-fold stimulation of the b-Wave Amplitude was reported recently for 15 µM NiCl2. The superfusion of isolate...
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antagonists of ionotropic γ aminobutyric acid receptors impair the nicl2 mediated stimulation of the electroretinogram b Wave Amplitude from the isolated superfused vertebrate retina
Acta Ophthalmologica, 2009Co-Authors: Siarhei A Siapich, Mohammed Banat, Walid Albanna, Jurgen Hescheler, Matthias Luke, Toni SchneiderAbstract:PURPOSE: NiCl(2) (15 microM) stimulates the electroretinogram (ERG) b-Wave Amplitude of vertebrate retina up to 1.5-fold through its blocking of E/R-type voltage-gated Ca(2+) channels. Assuming that such an increase is mediated by blocking the release of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) via ionotropic GABA receptors, we tested the effect of both GABA itself and GABA-receptor antagonists such as (-)bicuculline (1.51-fold increase) and (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA; 1.46-fold increase) on the b-Wave Amplitude. METHODS: Recording of the transretinal potentials from the isolated bovine retina. RESULTS: GABA (100 microM) reduced the b-Wave Amplitude only when NiCl(2) (15 microM) was applied first. Each antagonist applied on its own stimulated the b-Wave Amplitude only partially: subsequent NiCl(2) superfusion caused a small but additional increase, leading to a 1.69- and a 1.88-fold total increase of the Amplitude by Ni(2+) plus (-)bicuculline or Ni(2+) plus TPMPA, respectively. Only the application of both antagonists in combination, before superfusing low NiCl(2) (15 microM), completely prevented subsequent stimulation by NiCl(2) with a similar 1.90-fold total increase of b-Wave Amplitude. Those retina segments that did not respond to NiCl(2) could not be stimulated by (-)bicuculline and vice versa. CONCLUSION: The stimulatory effect of NiCl(2) on the ERG b-Wave Amplitude is mainly, but not only, mediated by a NiCl(2)-sensitive, Ca(v)2.3-triggered GABA release acting through ionotropic GABA-A and GABA-C receptors.
