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Biochimica Et Biophysica Acta Mar 2001Interaction of the local anesthetic dibucaine with small unilamellar vesicles of dimyristoylphosphatidylcholine (DMPC) and dioleoyl phosphatidylcholine (DOPC) containing...
Interaction of the local anesthetic dibucaine with small unilamellar vesicles of dimyristoylphosphatidylcholine (DMPC) and dioleoyl phosphatidylcholine (DOPC) containing different mol percents of cholesterol has been studied by fluorescence spectroscopy. Fluorescence measurements on dibucaine in presence of phospholipid vesicles containing various amounts of cholesterol yielded a pattern of variation of wavelength at emission maximum and steady-state anisotropy which indicated that the microenvironment of dibucaine is more polar and flexible in membranes that contain cholesterol than in membranes without cholesterol. Experiments on quenching of fluorescence from membrane-associated dibucaine by potassium iodide showed a marked increase in quenching efficiency as the cholesterol content of the vesicles was increased, demonstrating increased accessibility of the iodide quenchers to dibucaine in the presence of cholesterol, when compared to that in its absence. Total emission intensity decay profiles of dibucaine yielded two lifetime components of approximately 1 ns and approximately 2.8--3.1 ns with mean relative contributions of approximately 25 and approximately 75%, respectively. The mean lifetime in vesicles was 20--30% smaller than in the aqueous medium and showed a moderate variation with cholesterol content. Fluorescence measurements at two different temperatures in DMPC SUVs, one at 33 degrees C, above the phase transition temperature and another at 25 degrees C, around the main phase transition, indicated two different mode of dibucaine localization. At 25 degrees C dibucaine partitioned differentially in presence and absence of cholesterol. However, at 33 degrees C the apparent partition coefficients remained unaltered indicating differences in the microenvironment of dibucaine in presence and absence of cholesterol in the phospholipid membranes.
Topics: Anesthetics, Local; Anisotropy; Cholesterol; Dibucaine; Dimyristoylphosphatidylcholine; Drug Interactions; Lipid Bilayers; Phosphatidylcholines; Phospholipids; Spectrometry, Fluorescence; Temperature
PubMed: 11248213
DOI: 10.1016/s0005-2736(01)00268-1 -
Journal of Neurophysiology Apr 2012As an immediate consequence of stroke onset, failure of the Na(+)-K(+)-ATPase pump evokes a propagating anoxic depolarization (AD) across gray matter. Acute neuronal...
As an immediate consequence of stroke onset, failure of the Na(+)-K(+)-ATPase pump evokes a propagating anoxic depolarization (AD) across gray matter. Acute neuronal swelling and dendritic beading arise within seconds in the future ischemic core, imaged as changes in light transmittance (ΔLT). AD is itself not a target for drug-based reduction of stroke injury because it is generated in the 1st min of stroke onset. Peri-infarct depolarizations (PIDs) are milder AD-like events that recur during the hours following AD and contribute to infarct expansion. Inhibiting PIDs with drugs could limit expansion. Two types of drugs, "caines" and σ(1)-receptor ligands, have been found to inhibit AD onset (and may also oppose PID initiation), yet their underlying actions have not been examined. Imaging ΔLT in the CA1 region simultaneously with whole cell current-clamp recording from CA1 pyramidal neurons reveal that the elevated LT front and onset of the AD are coincident. Either dibucaine or carbetapentane pretreatment significantly delays AD onset without affecting resting membrane potential or neuronal input resistance. Dibucaine decreases excitability by raising spike threshold and decreasing action potential (AP) frequency, whereas carbetapentane eliminates the fast afterhyperpolarization while accentuating the slow afterhyperpolarization to reduce AP frequency. Orthodromic and antidromic APs are eliminated by dibucaine within 15 min but not by carbetapentane. Thus both drugs reduce cortical excitability at the level of the single pyramidal neuron but through strikingly different mechanisms. In vivo, both drugs would likely inhibit recurring PIDs in the expanding penumbra and so potentially could reduce developing neuronal damage over many hours poststroke when PIDs occur.
Topics: Action Potentials; Animals; CA1 Region, Hippocampal; Cell Hypoxia; Cyclopentanes; Dibucaine; Male; Neurons; Neuroprotective Agents; Organ Culture Techniques; Patch-Clamp Techniques; Rats; Rats, Sprague-Dawley
PubMed: 22279188
DOI: 10.1152/jn.00701.2011 -
Anesthesiology Feb 1981A chronic model for investigation of spinal anesthesia in the dog is described. This model incorporates the use of a chronically implanted catheter in the lumbar... (Comparative Study)
Comparative Study
A chronic model for investigation of spinal anesthesia in the dog is described. This model incorporates the use of a chronically implanted catheter in the lumbar subarachnoid space. An 18-gauge thin-walled Crawford needle is passes percutaneously into the subarachnoid space. An 18-gauge epidural catheter is then threaded through the needle into the subarachnoid space and the distal end attached to a special metal valve which is sutured under the skin. One-milliliter volumes of various local anesthetic solutions were injected intrathecally via the valve and catheter. Durations of the effects of the local anesthetics were evaluated. Duration which hind-limb paralysis persisted in the dog. The times to onset and durations of motor blockades were evaluated following the intrathecal injection of dibucaine, tetracaine, lidocaine, bupivacaine, chloroprocaine, and mepivacaine. Times to onset ranged from 1.1 to 2.3 min. Durations of motor blockade were longest for dibucaine and tetracaine, followed in order of decreasing duration by bupivacaine, lidocaine, chloroprocaine, and mepivacaine. The durations of subarachnoid conduction motor blockades in the dog are qualitatively similar to reported values for spinal anesthesia in man. Therefore, the technique described may provide a useful model to evaluate factors that may influence spinal anesthesia.
Topics: Anesthesia, Spinal; Anesthetics, Local; Animals; Bupivacaine; Catheters, Indwelling; Dibucaine; Dogs; Female; Half-Life; Injections, Spinal; Lidocaine; Male; Mepivacaine; Methods; Models, Biological; Procaine; Subarachnoid Space; Tetracaine
PubMed: 6894071
DOI: 10.1097/00000542-198102000-00009 -
The Journal of Biological Chemistry Jun 1993Calpain is distributed ubiquitously in virtually every tissue (Croall, D. E., and DeMartino, G. N. (1991) Physiol. Rev. 71, 813-846), but its physiological role remains...
Calpain is distributed ubiquitously in virtually every tissue (Croall, D. E., and DeMartino, G. N. (1991) Physiol. Rev. 71, 813-846), but its physiological role remains to be determined. The identification of its natural endogenous substrates would be of great interest. Since pp60src, a major tyrosine kinase in platelets, is known to be easily cleaved during purification from cells (Feder, D., and Bishop, J. M. (1990) J. Biol. Chem. 265, 8205-8211), we examined the possibility that it is an endogenous substrate of calpain. In the whole cell lysate from resting platelets, which was analyzed by Western blotting with monoclonal antibody 327, we found pp60src almost exclusively in a 60-kDa form, with a trace of 52-kDa form. Addition of A23187 (a calcium ionophore) or dibucaine, which are known to be activators of platelet calpain (Croall and DeMartino, 1991; Fox, J. E., Reynolds, C., Morrow, J. S., and Phillips, D. R. (1987) Blood 76, 2510-2519; Fox, J. E., Austin, C. D., Boyles, J. K., and Steffen, P. K. (1990b) J. Cell Biol. 111, 483-493), caused dose- and time-dependent cleavage of actin-binding protein and p235 protein (talin). At the same time, loss of the 60-kDa species of pp60src and generation of the 52-kDa (occasionally seen as doublets) and 47-kDa species were detected by the Western blotting. In platelets aggregated by 1 unit/ml thrombin, apparently identical cleavage products were found. The cleavage of pp60src was inhibited by calpeptin (20 microM), an inhibitor of calpain (Tsujinaka, T., Kajiwara, Y., Kambayashi, J., Sakon, M., Higuchi, N., Tanaka, T., and Mori, T. (1988) Biochem. Biophys. Res. Commun. 153, 1201-1208; Tsujinaka, T., Ariyoshi, H., Uemura, Y., Sakon, M., Kambayashi, J., and Mori, T. (1990) Life Sci. 46, 1059-1066; Fox, J. E., Clifford, C. C., and Austin, C. D. (1990) Blood 76, 2510-2519; Fox, J. E., Austin, C. D., Boyles, J. K., and Steffen, P. K. (1990) J. Cell. Biol. 111, 483-493; Fox, J. E., Austin, C. D., Clifford, C. C., and Steffen, P. K. (1991) J. Biol. Chem. 266, 13289-13295). Addition of EGTA (3 mM) to the extracellular media completely inhibited the cleavage of actin-binding protein, talin, and pp60src in response to A23187 (1 microM). Intact pp60src was distributed in both cytosolic and particulate (membrane) fractions. Cleaved species were found exclusively in the cytosolic fraction. pp60src-associated enolase kinase activity was reduced. Thus, pp60src is an endogenous substrate for calpain, the cleavage of which may have regulatory effects on the kinase.
Topics: Antibodies, Monoclonal; Blood Platelets; Blotting, Western; Calcimycin; Calcium; Calpain; Dimethyl Sulfoxide; Dipeptides; Egtazic Acid; Electrophoresis, Polyacrylamide Gel; Humans; Microfilament Proteins; Molecular Weight; Platelet Aggregation; Proto-Oncogene Proteins pp60(c-src); Substrate Specificity; Talin
PubMed: 7685344
DOI: No ID Found -
International Journal of Hyperthermia :... 2000Local anaesthetics, in addition to anaesthesia, induce the synthesis of heat shock proteins (HSPs), sensitize cells to hyperthermia, and increase the aggregation of...
Local anaesthetics, in addition to anaesthesia, induce the synthesis of heat shock proteins (HSPs), sensitize cells to hyperthermia, and increase the aggregation of nuclear proteins during heat shock. Anaesthetics are membrane active agents, and anaesthesia appears to be due to altered ion channel activity; however, the direct effect of heat shock is protein denaturation. These observations suggest that local anaesthetics may sensitize cells to hyperthermia by interacting with and destabilizing membrane proteins such that protein denaturation is increased. It is shown, using differential scanning calorimetry (DSC), that the local anaesthetics procaine, lidocaine, tetracaine and dibucaine destabilize the transmembrane domains of the Ca2+ -ATPase of sarcoplasmic reticulum and the band III anion transporter of red blood cells. The transmembrane domain of the Ca2+ -ATPase has a transition temperature (Tm) of denaturation of 61 degrees C which is decreased, for example, to 53 degrees C by 15 mM lidocaine. The degree of destabilization (deltaTm) by each anaesthetic is proportional to the lipid to water partition coefficient, and the increased sensitization by anaesthetics with larger partition coefficients and at higher pH suggests that the uncharged forms of the anaesthetics are responsible for destabilization. A Hill analysis of deltaTm for the Ca2+ -ATPase as a function of the concentration of anaesthetic in water gives dissociation constants (Kd) on the order of 10(-4) M, if binding occurs directly from the aqueous phase. This demonstrates moderate affinity binding. However, dissociation constants of 1-3 M are obtained, if binding occurs through the lipid phase, which demonstrates low affinity binding. Thus, the interaction of local anaesthetics with the Ca2+ -ATPase may be moderately specific or non-specific depending on the mechanism of interaction. The observation that local anaesthetics also destabilize the transmembrane domain of the band III protein of erythrocytes suggests that destabilization of transmembrane proteins is a general property of anaesthetics, which is at least in part a mechanism of sensitization to hyperthermia.
Topics: Anesthesia, Local; Anesthetics, Local; Animals; Anion Exchange Protein 1, Erythrocyte; Calcium-Transporting ATPases; Dibucaine; Erythrocytes; Fever; Heat-Shock Proteins; Lidocaine; Procaine; Rabbits; Tetracaine
PubMed: 10669313
DOI: 10.1080/026567300285385 -
Zeitschrift Fur Naturforschung. C,... 2001The interaction of the local anesthetic dibucaine with the isolated toad skin and membrane models is described. The latter consisted of human erythrocytes, isolated...
The interaction of the local anesthetic dibucaine with the isolated toad skin and membrane models is described. The latter consisted of human erythrocytes, isolated unsealed human erythrocyte membranes (IUM), large unilamellar vesicles (LUV) of dimyristoylphosphatidylcholine (DMPC) and phospholipid multilayers built-up of DMPC and dimyristoylphosphatidylethanolamine (DMPE), representative of phospholipid classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. Results indicate a significant decrease in the potential difference (PD) and in the short-circuit current (Isc) after the application of dibucaine in toad skin, which may be interpreted as reflecting inhibition of the active transport of ions. This finding might be explained on the basis of the results obtained from fluorescence spectroscopy and X-ray diffraction studies on membrane models. In fact, dibucaine induced structural perturbations in IUM, DMPC LUV and phospholipid multilayers. Scanning electron microscopy revealed that dibucaine induced erythrocyte stomatocytosis. According to the bilayer couple hypothesis an echinocytic type of shape change would have been expected given the preferential interaction of dibucaine with DMPC. Although it is still premature to define the molecular mechanism of action of dibucaine, the experimental results confirm the important role played by the phospholipid bilayers in the association of the anesthetic with cell membranes.
Topics: Animals; Anura; Biological Transport; Dibucaine; Dimyristoylphosphatidylcholine; Erythrocyte Membrane; Female; Humans; In Vitro Techniques; Lipid Bilayers; Liposomes; Male; Microscopy, Electron, Scanning; Models, Biological; Phosphatidylethanolamines; Skin; Sodium; X-Ray Diffraction
PubMed: 11531098
DOI: 10.1515/znc-2001-7-822 -
Biochimica Et Biophysica Acta Dec 2012The membrane location of the local anesthetics (LA) lidocaine, dibucaine, tetracaine, and procaine hydrochloride as well as their influence on phospholipid bilayers were...
The membrane location of the local anesthetics (LA) lidocaine, dibucaine, tetracaine, and procaine hydrochloride as well as their influence on phospholipid bilayers were studied by ³¹P and ¹H magic-angle spinning (MAS) NMR spectroscopy. The ³¹P NMR spectra of the LA/lipid preparations confirmed that the overall bilayer structure of the membrane remained preserved. The relation between the molecular structure of the LAs and their membrane localization and orientation was investigated quantitatively using induced chemical shifts, nuclear Overhauser enhancement spectroscopy, and paramagnetic relaxation rates. All three methods revealed an average location of the aromatic rings of all LAs in the lipid-water interface of the membrane, with small differences between the individual LAs depending on their molecular properties. While lidocaine is placed in the upper chain/glycerol region of the membrane, for dibucaine and procaine the maximum of the distribution are slightly shifted into the glycerol region. Finally for tetracaine the aromatic ring is placed closest to the aqueous phase in the glycerol/headgroup region of the membrane. The hydrophobic side chains of the LA molecules dibucaine and tetracaine were located deeper in the membrane and showed an orientation towards the hydrocarbon core. In contrast the side chains of lidocaine and procaine are oriented towards the aqueous phase.
Topics: Anesthetics, Local; Cell Membrane; Dibucaine; Hydrophobic and Hydrophilic Interactions; Lidocaine; Lipid Bilayers; Magnetic Resonance Spectroscopy; Procaine; Tetracaine
PubMed: 22842001
DOI: 10.1016/j.bbamem.2012.07.014 -
The Journal of Antibiotics Jul 1989The uptake of [3H]peplomycin-Cu(II) ([3H]PEP-Cu(II)) into various tumor cell lines was studied. The time course of [3H]PEP-Cu(II) uptake into AH66, AH66F, Ehrlich and...
The uptake of [3H]peplomycin-Cu(II) ([3H]PEP-Cu(II)) into various tumor cell lines was studied. The time course of [3H]PEP-Cu(II) uptake into AH66, AH66F, Ehrlich and P388 cells was biphasic. The first phase of uptake was completed within 5 minutes. The second, slower phase, of uptake into AH66, AH66F and Ehrlich cells increased linearly with incubation time, but that into P388 cells reached a plateau level. In L1210 cells, only the first rapid uptake was observed. The lower uptake into P388 and L1210 cells during the second phase may be related to their insensitivity to PEP. However, the uptake into AH66F cells was higher than that into AH66 cells, although AH66F cells were less sensitive to PEP than AH66 cells. Deamide PEP was detected in intact cells which had taken up [3H]PEP-Cu(II) during 4 hours. This confirmed that PEP-Cu(II) was transported into the cell, the copper removed and PEP metabolized to deamide PEP. [3H]PEP-Cu(II) uptake into AH66 and AH66F cells increased in proportion to the extracellular concentration of drug up to at least 200 micrograms/ml, suggesting that uptake was not mediated by a carrier system. Metabolic inhibitors such as NaN3 and 2,4-dinitrophenol enhanced [3H]PEP-Cu(II) uptake, but did not influence efflux. Uptake was also enhanced by membrane modifiers such as dibucaine and chlorpromazine which increase the fluidity of lipid membranes. The results suggest that PEP-Cu(II) was taken up into tumor cells by passive diffusion, controlled by an energy-dependent cell membrane barrier.
Topics: Animals; Antibiotics, Antineoplastic; Bleomycin; Carcinoma, Ehrlich Tumor; Chlorpromazine; Chromatography, High Pressure Liquid; Colchicine; Dibucaine; Dose-Response Relationship, Drug; Leukemia L1210; Leukemia P388; Liver Neoplasms, Experimental; Peplomycin; Permeability; Time Factors; Tumor Cells, Cultured; Vinblastine
PubMed: 2473972
DOI: 10.7164/antibiotics.42.1163 -
Biophysical Journal Mar 1980Gating current (Ig) underlying Na-channel activation is large enough to enable resolution of components both preceding and paralleling Na conductance (gNa) turn-on. For...
Gating current (Ig) underlying Na-channel activation is large enough to enable resolution of components both preceding and paralleling Na conductance (gNa) turn-on. For large depolarizations (beyond +20 mV), an additional "slow phase" of Ig is observed during a time when Na activation is already complete, but when K-channel opening is just becoming detectable. If Na- and K-channel gating are similar, the slow kinetics and long delay for K activation predict that K channel Ig must be relatively small and slow. Externally applied dibucaine almost totally blocks gNa and greatly reduces the fast (Na channel) Ig without altering gK or the Ig slow phase. The slow phase of Ig depends in part of the presence of functional K channels. Selective diminution in amplitude of the slow phase is consistently observed after a 30-min perfusion with both external and internal K-free media, a procedure which destroys nearly all K channels. This decrease of Ig amounts to approximately 10% of the total charge movements at +40 to +80 mV, with gating charge and K channels disappearing in a ratio of less than 1 e- per picosiemens of gK. These findings are consistent with the idea that part of the Ig slow phase represents gating current generated by the early steps in K-channel activation.
Topics: Animals; Axons; Decapodiformes; Dibucaine; Electric Conductivity; Ion Channels; Kinetics; Potassium; Sodium
PubMed: 6271271
DOI: 10.1016/S0006-3495(80)85147-2 -
Journal of Psychiatry & Neuroscience :... Mar 2010Enlarged ventricles and reduced hippocampal volume are consistently found in patients with first-episode schizophrenia. Studies investigating brain structure in...
BACKGROUND
Enlarged ventricles and reduced hippocampal volume are consistently found in patients with first-episode schizophrenia. Studies investigating brain structure in antipsychotic-naive patients have generally focused on the striatum. In this study, we examined whether ventricular enlargement and hippocampal and caudate volume reductions are morphological traits of antipsychotic-naive first-episode schizophrenia.
METHODS
We obtained high-resolution 3-dimensional T1-weighted magnetic resonance imaging scans for 38 antipsychotic-naive first-episode schizophrenia patients and 43 matched healthy controls by use of a 3-T scanner. We warped the brain images to each other by use of a high-dimensional intersubject registration algorithm. We performed voxel-wise group comparisons with permutation tests. We performed small volume correction for the hippocampus, caudate and ventricles by use of a false discovery rate correction (p < 0.05) to control for multiple comparisons. We derived and analyzed estimates of brain structure volumes. We grouped patients as those with (n = 9) or without (n = 29) any lifetime substance abuse to examine the possible effects of substance abuse.
RESULTS
We found that hippocampal and caudate volumes were decreased in patients with first-episode schizophrenia. We found no ventricular enlargement, differences in global volume or significant associations between tissue volume and duration of untreated illness or psychopathology. The hippocampal volume reductions appeared to be influenced by a history of substance abuse. Exploratory analyses indicated reduced volume of the nucleus accumbens in patients with first-episode schizophrenia.
LIMITATIONS
This study was not a priori designed to test for differences between schizophrenia patients with or without lifetime substance abuse, and this subgroup was small.
CONCLUSION
Reductions in hippocampal and caudate volume may constitute morphological traits in antipsychotic-naive first-episode schizophrenia patients. However, the clinical implications of these findings are unclear. Moreover, past substance abuse may accentuate hippocampal volume reduction. Magnetic resonance imaging studies addressing the potential effects of substance abuse in antipsychotic-naive first-episode schizophrenia patients are warranted.
Topics: Adolescent; Adult; Benzydamine; Brain; Caudate Nucleus; Cerebral Ventricles; Dibucaine; Drug Combinations; Female; Hippocampus; Humans; Hyaluronoglucosaminidase; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Nucleus Accumbens; Organ Size; Piperidines; Psychiatric Status Rating Scales; Schizophrenia; Substance-Related Disorders; Time Factors; Young Adult
PubMed: 20184807
DOI: 10.1503/jpn.090049