Anestesia intravenosa contínua com cetamina racêmica ou dextrocetamina e detomidina em cadelas / [Continuous intravenous anesthesia with racemic ketamine or dextroketamine and detomidine in female dogs]

Objetivou-se com este estudo comparar a associação de detomidina e cetamina ou dextrocetamina, por via intravenosa contínua, em oito cadelas submetidas a dois protocolos: GCD - indução anestésica com 5mg/kg e infusão intravenosa contínua de 20mg/kg/h de cetamina; e GDD - indução com 3,5mg/kg e infusão de 14mg/kg/h de dextrocetamina. Associou-se detomidina, 30µg/kg/h, em ambos os grupos. Registraram-se frequência cardíaca (FC), pressão arterial (PA), frequência respiratória (f), temperatura (TC), miorrelaxamento, analgesia, hemogasometria e eletrocardiograma, antes e 15 minutos após a MPA (Mbasal e Mmpa); após o início da infusão (Mic); a cada 10 minutos até 90 minutos (M10, M20, M30, M40, M50, M60, M70, M80 e M90); e 30 minutos após o fim da infusão (M120). Foi observada bradicardia em Mmpa no GCD e de Mmpa a M10 no GDD. Ocorreu hipotensão em Mmpa e hipertensão a partir de Mic. A f diminuiu de M10 a M30. Foram observados: onda T de alta amplitude, bloqueios atrioventriculares e parada sinusal. Ocorreu acidose respiratória. O período de recuperação foi de 219,6±72,3 minutos no GCD e de 234,1±96,8 minutos no GDD. A cetamina e a dextrocetamina, associadas à detomidina por infusão contínua, causam efeitos cardiorrespiratórios e anestésicos similares.(AU)

The combination of detomidine and ketamine or dextrocetamine for continuous intravenous infusion was compared in eight female dogs submitted to two protocols: GCD - 5mg/kg of anesthetic induction and continuous intravenous infusion of ketamine 20mg/kg/h; and GDD - induction with 3.5mg/kg and infusion of 14mg/kg/h of dextrocetamine. Detomidine, 30µg/kg/h was associated in both groups. Heart rate (HR), blood pressure (BP), respiratory rate (RR), temperature (CT), myorelaxation, analgesia, blood gas analysis and electrocardiogram were recorded before and 15 minutes after MPA (Mbasal and Mmpa); after the start of infusion (Mic); every 10 minutes to 90 minutes (M10, M20, M30, M40, M50, M60, M70, M80 and M90); and 30 minutes after the end of infusion (M120). Bradycardia was observed in Mmpa in GCD and from Mmpa to M10 in GDD. There was hypotension in Mmpa and hypertension from Mic. The RR decreased from M10 to M30. High amplitude T wave, atrioventricular blocks and sinus arrest were observed. Respiratory acidosis occurred. The recovery period was 219.6±72.3 minutes in GCD and 234.1±96.8 minutes in GDD. Ketamine and S+ ketamine associated with detomidine for continuous infusion cause cardiorespiratory and similar anesthetic effects.(AU)

Broccoli-shaped biosensor hierarchy for electrochemical screening of noradrenaline in living cells.

Monitoring and determination of ultra-trace concentrations of monoamine neurotransmitter such as noradrenaline (NA) in living cells with simple, sensitive and selective assays are significantly interesting. We design NA-electrode sensing system based on C-, N-doped NiO broccoli-like hierarchy (CNNB). The spherical broccoli-head umbrella architectures associated with nano-tubular arrangements enabled to tailor NA biosensor design. The homogenous doping and anisotropic dispersion of CN nanospheres along the entire NB head nanotubes lead to creating of abundant electroactive sites in the interior tubular vessels and outer surfaces for ultrasensitive detection of NA in living cells such as PC12. The CNNB biosensor electrodes showed efficient electrocatalytic activity, enhanced kinetics for electrooxidation of NA, and fast electron-transfer between electrode-electrolyte interface surfaces, enabling synergistic enhancement in sensitivity, and selectivity at a low-detectable concentration of ∼ 6nM and reproducibility of broccoli-shaped NA-electrodes. The integrated CNNB biosensor electrodes showed evidence of monitoring and screening of NA released from PC12 cells under K+ ion-extracellular stimulation process. The unique features of CNNB in terms of NA-selectivity among multi-competitive components, long-term stability during the detection of NA may open their practical, in-vitro application for extracellular monoamine neurotransmitters detection in living cells.

FeMoO4 based, enzyme-free electrochemical biosensor for ultrasensitive detection of norepinephrine.

Herein, FeMoO4 (FM) nanorods were synthesized by a template-free, facile, hydrothermal method in an aqueous medium. The surface morphology of FeMoO4 was identified with field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray diffraction (XRD) was performed to identify the crystallographic nature of the as-synthesized FeMoO4. The as-synthesized material was used as an active electrode material for the oxidation of a neurotransmitter (i.e. norepinephrine (NE)) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. FeMoO4 possesses polycrystallanity and bimetallic character, which helps to enhance the performance of the FM/GCE as compared to the GCE. The enhanced performance was also due to the formation of Fe (II)-dioxygen complexes, which catalyze the oxidation of NE. Meticulous observations taken from CV studies proved the diffusion-controlled nature of the reaction with a diffusion coefficient of 1.10×10(-4)cm(2)/s and a standard heterogeneous rate constant of 4.078×10(-3)cm/s. The amperometric response of NE on the FM/GCE showed a linear increase in the current between 5.0×10(-8)M and 2.0×10(-4)M with a detection limit of 3.7×10(-9)M. In the amperometric study, the time required to reach the 98% steady state response, after successive additions of 50nM NE, was less than 3s. The FM/GCE showed good sensitivity, and stability for the determination of NE.

Novel spectroscopic methods for determination of Cromolyn sodium and Oxymetazoline hydrochloride in binary mixture.

New accurate, sensitive and selective spectrophotometric and spectrofluorimetric methods were developed and subsequently validated for determination of Cromolyn sodium (CS) and Oxymetazoline HCl (OXY) in binary mixture. These methods include 'H-point standard addition method (HPSAM) and area under the curve (AUC)' spectrophotometric method and first derivative synchronous fluorescence spectroscopic (FDSFS) method. For spectrophotometric methods, absorbances were recorded at 241.5nm and 274.9nm for HPSAM and the wavelength was selected in ranges 232.0-254.0nm and 216.0-229.0nm for AUC method, where the concentration was obtained by applying Cramer's rule. For FDSFS method, the first-derivative synchronous fluorescence signal was measured at 290.0nm, using Δλ=145.0nm. The suggested methods were validated according to International Conference of Harmonization (ICH) guidelines and the results revealed that they were precise and reproducible. All the obtained results were statistically compared with those of the reported method and there was no significant difference.

Ion selective phosphotungestate and beta-cyclodextrin based membrane electrodes for stability-indicating determination of midodrine hydrochloride.

This paper reports the construction and evaluation of two ion selective electrodes for the determination midodrine hydrochloride (MD) by direct potentiometry in pure drug substance and in tablet formulations. Precipitation based technique was used for fabrication of the first membrane sensor (sensor 1) using phosphotungestate (PT) and dioctylphthalate (DOP) as cation exchanger and solvent mediator, respectively. beta-cyclodextrin (beta-CD)-based technique with PT as a fixed anionic site in PVC matrix was used for fabrication of the second membrane sensor (sensor 2). The proposed sensors showed fast, stable Nernstian responses of 54 and 56 mV/decade for sensors 1 and 2, respectively, across a relatively wide MD concentration range (1x 10(-4) to 1 x 10(-1) mol/L and 5 x 10(-5) to 1 x 10(-1) mol/L for sensor 1 and 2, respectively) in the pH range of 5-7. Sensor I and sensor 2 can be used for three and two weeks, respectively without any measurable change in sensitivity. The suggested electrodes succeeded to determine intact MD in the presence of up to 10% of its degradation product and displayed good selectivity in presence of common inorganic and organic species.

Simultaneous determination of antazoline and naphazoline by the net analyte signal standard addition method and spectrophotometric technique.

A novel net analyte signal standard addition method (NASSAM) was used for simultaneous determination of the drugs anthazoline and naphazoline. The NASSAM can be applied for determination of analytes in the presence of known interferents. The proposed method is used to eliminate the calibration and prediction steps of multivariate calibration methods; the determination is carried out in a single step for each analyte. The accuracy of the predictions against the H-point standard addition method is independent of the shape of the analyte and interferent spectra. The net analyte signal concept was also used to calculate multivariate analytical figures of merit, such as LOD, selectivity, and sensitivity. The method was successfully applied to the simultaneous determination of anthazoline and naphazoline in a commercial eye drop sample.

Frontal analysis of cell-membrane chromatography for determination of drug-alpha(1D) adrenergic receptor affinity.

The aim of the present study was to determine drug-alpha(1D) adrenergic receptor (AR) affinity by frontal analysis of cell-membrane chromatography (CMC). The cell-membrane stationary phase (CMSP) was prepared by immobilizing rat aorta cell membranes on porous silica, and the resulting CMSP was used to determine drug binding affinity to alpha(1D)-AR by frontal analysis. The CMSP of rat aorta was stable and reproducible. Relative binding affinities (dissociation constant, K(d)) were determined by frontal chromatography for prazosin (166.13+/-18.36 nmol), BMY7378 (537.40+/-30.84 nmol), phentolamine (646.92+/-23.17 nmol), 5-methylurapidil (725.66+/-25.48 nmol), oxymetazoline (910.56+/-40.62 nmol) and methoxamine (1299.27+/-51.73 nmol). These results were consistent with the affinity rank order and showed a good correlation with the affinity of the same compounds for the cloned alpha(1D)-AR subtype obtained from radioligand-binding assay. The study demonstrates that frontal analysis of CMC may be used for direct determination of drug-receptor binding interactions, and that CMC is an alternative reliable method to quantitatively study ligand-receptor interactions.

A rapid and sensitive LC/MS/MS assay for the quantitation of brimonidine in ocular fluids and tissues.

We report here the development and validation of an LC/MS/MS method for the rapid and accurate quantitation of brimonidine in ocular tissues and fluids using brimonidine-d(4) as an internal standard (IS). Brimonidine was extracted from retina, iris/ciliary body, and vitreous humor samples with an acetonitrile:water (1:1) solution followed by sonication and vortexing. Aliquots of aqueous humor, iris/ciliary body, retina, and vitreous humor samples were diluted with acetonitrile containing IS and were separated on a reverse-phase HPLC column under isocratic conditions. Brimonidine (m/z transition: 292-->212) and the internal standard (m/z transition: 296-->216) were analyzed via multiple-reaction monitoring (MRM) in the positive electrospray mode on a 4000 Q TRAP instrument. The total analysis time for each sample was less than 2.0 min. The calibration curves for brimonidine (1-1000 ng/mL) were constructed using a linear regression with 1/x(2) weighing. The lower limit of quantitation for brimonidine was 1.0 ng/mL for aqueous humor, 10 ng/g for iris/ciliary body, 12.5 ng/g for retina, and 1.6 ng/g for vitreous humor. Intra-day and inter-day estimates of accuracy and precision were within 15% of their nominal values indicating that the method is reliable for quantitation of brimonidine in ocular tissues and fluids.

Method development and validation for the simultaneous determination of cetirizine dihydrochloride, paracetamol, and phenylpropanolamine hydrochloride in tablets by capillary zone electrophoresis.

A simple, selective, and cost effective capillary zone electrophoresis (CZE) method has been developed for the simultaneous separation and determination of cetirizine dihydrochloride (CTZ), paracetamol (PARA), and phenylpropanolamine hydrochloride (PPA) in tablets. A 10 mM sodium tetraborate background electrolyte (BGE) solution (pH 9.0) was found to be suitable for separation of all the analytes. An uncoated fused-silica capillary of a total length of 76 cm (effective length 64.5 cm) was used for separation. All the analytes were completely separated within 10 min at the applied voltage of 20 kV (current produced approximately 21 microA), and detection was performed at 195 nm with an UV detector. Ibuprofen was used as internal standard (I.S.) for the quantification of the drugs. Validation of the method was performed in terms of linearity, accuracy, precision, limit of detection (LOD), and quantification (LOQ). The linearity of the calibration curves for CTZ, PARA, and PPA (tested range) were 2-50 microg ml(-1) (r(2)=0.9982), 10-1000 microg ml(-1) (r(2)=0.9978), and 10-100 microg ml(-1) (r(2)=0.9986), respectively. The proposed method has been applied for the determination of active ingredients in tablets, and the recovery was found to be > or =98.60% with the relative standard deviation (R.S.D.) < or =1.56%. The LOQ of the CTZ, PARA, and PPA was found to be 2.0, 2.0, and 4.0 microg ml(-1), respectively. There were no interfering peaks due to the excipients present in the pharmaceutical tablets. Thus, the proposed method is simple and suitable for the simultaneous analysis of active ingredients in tablet dosage forms.

[Use of hyaluronic acid cleaving enzymes for absorption acceleration. Results of an in vitro study with xylazine and ketamine]. / Einsatz von Hyaluronsäure spaltenden Enzymen zur Resorptionsbeschleunigung. Ergebnisse einer In-vitro-Studie mit Xylazin und Ketamin.

The so-called "Hellabrunner Mischung", (combination of xylazine and ketamine with hyaluronidase) is frequently used for the immobilisation of wildlife animals. The enzyme hyaluronidase shall improve the distribution of the intramuscularly or subcutaneously administered compounds in the tissue and enhance their absorption. These enhancing effects of two hyaluronate lyases of bacterial origin (Streptococcus agalactiae and Streptococcus equisimilis) and a testicular hyaluronidase were compared in an in vitro test. Using the isolated perfused bovine udder, 2 ml of a solution were administered subcutaneously containing 125 mg/ml xylazine and 100 mg/ml ketamine and one of the above mentioned enzymes (150 I.U.). All three enzymes enhanced the absorption rate of xylazine and ketamine determined by measurement of the concentration in the perfusate. The bacterial hyaluronate lyases were significantly more efficient, especially during the clinically important first minutes after administration.

Determination of octopamine, synephrine and tyramine in Citrus herbs by ionic liquid improved 'green' chromatography.

Without adding any volatile organic solvents, aqueous solutions of room temperature ionic liquids (RTILs) were used as 'green' mobile phases to determine octopamine, synephrine and tyramine by liquid chromatography. The problems of the adrenergic amines separation, such as band tailing, low retention and low resolution were solved successfully by using RTIL. The effect of 1-ethyl-3-methylimidazolium tertafluoroborate ([EMIM][BF4]) was the best in the six investigated RTILs. The concentration of [EMIM][BF4], mobile phase pH and column temperature, which influenced the chromatographic behaviors of the analytes, were investigated in detail. The change of retention factors caused by pH shift was obviously suppressed by [EMIM][BF4]. The sensitivity, accuracy and repeatability of this method were found to be satisfactory. The contents of adrenergic amines in several Citrus herbs and extracts, such as Fructus aurantii immaturus, were simultaneously determined by this 'green' chromatographic method.

A rapid derivative spectrophotometric method for simultaneous determination of naphazoline and antazoline in eye drops.

A zero-crossing first-derivative spectrophotometric method is applied for the simultaneous determination of naphazoline hydrochloride and antazoline phosphate in eye drops. The measurements were carried out at wavelengths of 225 and 252 nm for naphazoline hydrochloride and antazoline phosphate, respectively. The method was found to be linear (r2>0.999) in the range of 0.2-1 microg/ml for naphazoline hydrochloride in the presence of 5 microg/ml antazoline phosphate at 225 nm. The same linear correlation (r2>0.999) was obtained in the range of 1-10 microg/ml of antazoline phosphate in the presence of 0.5 microg/ml of naphazoline hydrochloride at 252 nm. The limit of determination was 0.2 microg/ml and 1 microg/ml for naphazoline hydrochloride and antazoline phosphate, respectively. The method was successfully used for simultaneous analysis of naphazoline hydrochloride and antazoline phosphate in eye drops without any interference from excipients and prior separation before analysis.

A fluorescence optosensor for analyzing naphazoline in pharmaceutical preparations. Comparison with other sensors.

We have developed an optical sensor for determining and quantifying naphazoline (NPZ) based on its inherent fluorescence property. We have placed a non-ionic-exchanger solid support (Amberlite XAD-7) in a flow cell in the light path of the excitation beam and the fluorescence signal for NPZ is continuously monitored at lambda(exc/nm)=294/306 nm. The response time for this sensor is acceptably fast, 80s, obtaining a detection limit of 2.6 ng mL(-1) with standard deviations of 2.0% at 125 ng mL(-1). This device has been satisfactorily applied to two commercial formulations and its selectivity has been demonstrated with an interference study. The advantages have been compared with the only published sensor for determining NPZ in pharmaceutical preparations and with other analytical methods in the literature.

Efeitos da administração epidural de amitraz, xilazina ou dimetil sulfóxido em vacas / Effects of epidural injection of amitraz, xylazine or dimethyl sulfoxide in cows

Avaliaram-se os efeitos da injeção epidural de amitraz (0,4mg/kg), xilazina (0,05mg/kg) ou dimetil sulfóxido 10 por cento (5,0ml) sobre a freqüência cardíaca (FC), pressão arterial sistólica (PAS), freqüência respiratória (FR), motilidade ruminal (MR), temperatura retal (TR), altura de cabeça (AC) e latência das respostas a estímulos nociceptivos nas regiões da coxa (LECC) e coroa do casco (LRRM) de vacas. Houve diminuição da FC e da MR nos grupos xilazina e amitraz. O tratamento com xilazina resultou em alterações na FR, PAS e AC. LECC e LRRM foram maiores nos tratamentos com agonistas alfa-2. Nas doses utilizadas, o amitraz aumentou a latência de resposta a estímulo nociceptivo em menor grau que a xilazina, sem induzir efeitos colaterais sistêmicos severos, em vacas.

Desipramine attenuates loss of cardiac sympathetic neurotransmitters produced by congestive heart failure and NE infusion.

We reported recently that inhibition of neuronal reuptake of norepinephrine (NE) by desipramine prevented the reduction of sympathetic neurotransmitters in the failing right ventricle of right heart failure animals. In this study, we studied whether desipramine also reduced the sympathetic neurotransmitter loss in animals with left heart failure induced by rapid ventricular pacing (225 beats/min) or after chronic NE infusion (0.5 microg. kg(-1). min(-1)). Desipramine was given to the animals for 8 wk beginning with rapid ventricular pacing or NE infusion. Animals receiving no desipramine were studied as controls. We measured myocardial NE content, NE uptake activity, and sympathetic NE, tyrosine hydroxylase, and neuropeptide Y profiles by histofluorescence and immunocytochemical techniques. Effects of desipramine on NE uptake inhibition were evidenced by potentiation of the pressor response to exogenous NE and reduction of myocardial NE uptake activity. Desipramine treatment had no effect in sham or saline control animals but attenuated the reduction of sympathetic neurotransmitter profiles in the left ventricles of animals with rapid cardiac pacing and NE infusion. In contrast, the panneuronal marker protein gene product 9.5 profile was not affected by either rapid pacing or NE infusion, nor was it changed by desipramine treatment in the heart failure animals. The study confirms that excess NE contributes to the reduction of cardiac sympathetic neurotransmitters in heart failure. In addition, it shows that the anatomic integrity of the sympathetic nerves is relatively intact and that the neuronal damaging effect of NE involves the uptake of NE or its metabolites into the sympathetic nerves.

Differential pre- and postsynaptic effects of desipramine on cardiac sympathetic nerve terminals in RHF.

Right heart failure (RHF) is characterized by chamber-specific reductions of myocardial norepinephrine (NE) reuptake, beta-receptor density, and profiles of cardiac sympathetic nerve ending neurotransmitters. To study the functional linkage between NE uptake and the pre- and postsynaptic changes, we administered desipramine (225 mg/day), a NE uptake inhibitor, to dogs with RHF produced by tricuspid avulsion and progressive pulmonary constriction or sham-operated dogs for 6 wk. Animals receiving no desipramine were studied as controls. We measured myocardial NE uptake activity using [(3)H]NE, beta-receptor density by [(125)I]iodocyanopindolol, inotropic responses to dobutamine, and noradrenergic terminal neurotransmitter profiles by glyoxylic acid-induced histofluorescence for catecholamines, and immunocytochemical staining for tyrosine hydroxylase and neuropeptide Y. Desipramine decreased myocardial NE uptake activity and had no effect on the resting hemodynamics in both RHF and sham animals but decreased myocardial beta-adrenoceptor density and beta-adrenergic inotropic responses in both ventricles of the RHF animals. However, desipramine treatment prevented the reduction of sympathetic neurotransmitter profiles in the failing heart. Our results indicate that NE uptake inhibition facilitates the reduction of myocardial beta-adrenoceptor density and beta-adrenergic subsensitivity in RHF, probably by increasing interstitial NE concentrations, but protects the cardiac noradrenergic nerve endings from damage, probably via blockade of NE-derived neurotoxic metabolites into the nerve endings.

Adrenergic signalling between rat taste receptor cells.

In taste buds, synaptic transmission is traditionally thought to occur from taste receptor cells to the afferent nerve. This communication reports the novel observation that taste receptor cells respond to adrenergic stimulation. Noradrenaline application inhibited outward potassium currents in a dose-dependent manner. This inhibition was mimicked by the beta agonist isoproterenol and blocked by the beta antagonist propranolol. The alpha agonists clonidine and phenylephrine both inhibited the potassium currents and elevated intracellular calcium levels. Inwardly rectifying potassium currents were unaffected by adrenergic stimulation. Experiments using the RT-PCR technique demonstrate that lingual epithelium expresses multiple alpha (alpha1a, alpha1b, alpha1c, alpha1d, alpha2a, alpha2b, alpha2c) and beta (beta1, beta2) subtypes of adrenergic receptors, and immunocytochemistry localized noradrenaline to a subset of taste receptor cells. Collectively, these data imply strongly that adrenergic transmission within the taste bud may play a paracrine role in taste physiology.

Evaluation and application of liquid chromatographic columns coated with 'intelligent' ligands. II. Phospholipid column.

The stationary phases of octadecylsilica (ODS) coated with phospholipid have been developed as a model of artificial lipid membranes for liquid chromatographic columns. An ODS column coated with phospholipid can be readily prepared by recycling a solution containing L-alpha-dipalmitoyl-phosphatidylcholine (DPPC) through an ODS column in a closed loop. DPPC becomes absorbed on the ODS surfaces by hydrophobic interaction between the acyl group of DPPC and the octadecyl group of the ODS surfaces. The DPPC column was usable when a mobile phase containing 30% (v/v) acetonitrile was delivered without detachment of the DPPC from the ODS surfaces. The retention behavior of ionic solutes on the DPPC column suggested that the retention was based on both ionic and electrostatic interactions between the solutes and the stationary phase. The retention factors on the DPPC column correlated well with the partition coefficients in liposome systems for alpha-adrenoceptor agonists and beta-blockers, indicating that the partition of solutes between the coated phase and buffer was similar to that in the liposome/water system. The DPPC column can be used in screening studies to predict the binding properties of drugs onto lipid membranes.

Sympathetic nervous system activity in adipose tissues during pregnancy and lactation of the rat.

The concentration and turnover of norepinephrine in white adipose and liver tissues were determined in pregnant, lactating, and age-matched virgin rats to elucidate the adaptations in sympathetic nervous system activity. In study 1, at d 18 of pregnancy and d 7 and 21 of lactation, animals were killed, and liver and cardiac perimetrial and retroperitoneal adipose depots were quick-frozen and then assayed for norepinephrine as a gross estimate of sympathetic innervation. In study 2, the same design was used to measure the turnover of norepinephrine as a measure of sympathetic activity. Animals were treated with alpha-methylparatyrosine, an inhibitor of norepinephrine synthesis, and killed at 0, 1.5, and 3 h after injection. In pregnant animals, basal norepinephrine concentrations were decreased compared with unbred controls in perimetrial and retroperitoneal depots. By d 21 of lactation, all adipose depots from lactating animals had more norepinephrine than did controls. The turnover of norepinephrine decreased in noncardiac adipose depots of pregnant animals. By d 21 of lactation, norepinephrine concentration was greater in all of the adipose depots than in controls. The turnover rate was faster in all adipose tissue depots but only significantly different in the cardiac depot. Sympathetic nervous activity in adipose tissue is diminished in pregnant rats, presumably to save energy for fetal growth and maternal fat storage. In late lactation, activity is increased, presumably to direct fatty acids away from adipose tissue towards milk production. The data from this study are consistent with the hypothesis that the sympathetic nervous system plays a role in the regulation of adipose metabolism in lactation.