Local Procaine Research Articles

Multiple hypothalamic sites control the frequency of hippocampal theta rhythm.

Stimulation of a neural pathway originating in the brainstem reticular formation, with synapses in the medial hypothalamus, activates the hippocampal theta rhythm. The frequency of reticular-elicited theta is determined in the medial supramammillary nucleus (mSuM) completely in anaesthetised rats, but only partially when the animal is awake. We tested other medial hypothalamic sites for their capacity to control theta frequency in awake rats. Blockade of sodium channels (1 microl fast infusion of the local anaesthetic procaine, experiment 1) or increased inhibition by GABA (Chlordiazepoxide [CDP], experiment 2) was found to reduce or increase the frequency of reticular-elicited theta, depending on the precise site of injection, in the region of the dorsomedial hypothalamic nucleus (DMH) and the posterior hypothalamic nucleus (PH). A band of null sites for CDP was located in the region of the ventral border of PH and dorsal border of mSuM. Using 0.5 and 1 microl CDP, and slow infusions (experiment 3), it was found that effective PH sites were also separate from mSuM in the rostrocaudal direction. In experiment 4, the DMH/PH region was mapped with unilateral and bilateral slow infusions of 0.5 microl CDP. CDP significantly reduced frequency in medial (periventricular) and dorsal PH, but not DMH. Bilateral injections appeared to generally sum the usual effects of unilateral injection, producing effects of intermediate size. However, the absolute frequency change in any given site, or with any pair of sites, did not exceed 1 Hz, which is similar to what is seen with single injections in mSuM. Overall, it appears that at, any one time, theta frequency may be determined by a complex interplay between distinct but interacting modulatory regions in the medial hypothalamus.

Pharmacokinetics and pharmacodynamics of a new local anesthetic agent.

We compared the effects of local anesthetics procaine, amethocaine (dicaine), bupivacaine, and a new agent RU-1148 on hydrolytic activity of human plasma butyrylcholinesterase. The butyrylcholinesterase-blocking activity of the test substances decreased in the following order: bupivacaine>amethocaine>procaine>RU-1148. The study of the capacity of these agents to form complexes with human plasma proteins and serum albumin showed that RU-1148 in therapeutic concentrations was transported by human serum albumin,beta-globulin, and acid glycoproteins. Study of the mechanisms of pharmacodynamic interactions between clonidine and RU-1148 demonstrated good prospects of their combined use.

The tertiary amine local anesthetic dibucaine binds to the membrane skeletal protein spectrin

The quinoline-based tertiary amine dibucaine has been shown to bind the membrane skeletal protein spectrin with a dissociation constant of 3.5×10−5 M at 25°C. Such binding is detected by monitoring the quenching of the tryptophan fluorescence intensity with increasing concentrations of dibucaine only and not with the benzene-based local anesthetics procaine, tetracaine and lidocaine. Binding of dibucaine also indicated changes in the tertiary structure of spectrin indicated by a circular dichroism spectrum in the near-UV region due to absorption of the aromatic side chains. The thermodynamic parameters associated with the binding indicated the interaction of dibucaine and spectrin to be enthalpy-driven and insensitive to an increase in the ionic strength of the buffer.

Protective effect of procaine hydrochloride on cisplatin-induced alterations in rat kidney.

Efforts have been made to reduce the undesirable side effects of cisplatin, mainly nephro- and neurotoxicity, but their reduction is usually accompanied by a concomitant inhibition of antitumor activity. The local anesthetic procaine hydrochloride (P.HCl) improves the therapeutic index of cisplatin not only by the reduction of its nephro- and hemotoxicity, but also by an increase of its antitumor activity. We therefore investigated the effects of a combined treatment of cisplatin and P.HCl on rat kidneys and compared this to kidneys from rats treated with a toxic dose of cisplatin or P.HCl alone. Treatment with a saline solution was used as control. Dehydrogenase activities [succinate dehydrogenase (SDH) and NADPH diaphorase reaction demonstrating nitric oxide synthase (NOS/NADPHd)] and phosphatase activities [K -nitrophenyl phosphatase (K pNPPase), alkaline phosphatase (AlPase) and acid phosphatase (AcPase)] were studied on cryostatic sections of kidneys from controls and treated rats. Evidence of heavy morphological damage and altered AlPase and AcPase activities induced by cisplatin were observed in the S3 segment of the proximal tubules. In addition, SDH and K pNPPase activities showed some changes in the distal tubule cells. The NOS/NADPHd activity in macula densa was drastically reduced. Combined treatment of cisplatin and P.HCl greatly attenuated morphological alterations of the rat kidney and reduced the changes in enzyme activities, except for NOS/NADPHd activity, compared to the cisplatin-treated group of animals. The study indicates that, in cisplatin-induced nephrotoxicity, a significant role is played by enzyme activities, in particular K pNPPase and NOS/NADPHd, and that P.HCl can mitigate the nephrotoxicity of cisplatin, possibly by influencing some enzyme activities involved in important renal metabolic pathways.

Determination of para-aminobenzoic acid, a degradation product of procaine hydrochloride, by zero-crossing first-derivative spectrometry.

A first derivative spectrometric method has been developed for the determination of the para-aminobenzoic acid (PABA), a related substance and degradation product of the local anesthetic procaine hydrochloride (PH). The wavelength selected for the determination of para-aminobenzoic acid in the presence of procaine was 290 nm. At this wavelength the calibration graphs relating the amplitude of the signals to the concentration of para-aminobenzoic acid were linear up to 10 mg L(-1). The detection limit of para-aminobenzoic acid was 0.70 mg L(-1). The method is simple and rapid and does not require preliminary treatment of the sample. The method was validated.

Partitioning of uncharged local anesthetic benzocaine into model biomembranes

The partitioning of uncharged local anesthetic benzocaine (BzC) into molecular aggregates formed by cationic surfactant decylammonium chloride (DeAC) and phospholipid dipalmitoylphosphatidylcholine (DPPC) was studied from the surface tension and light transmittance measurements. The quantities concerning the partitioning of BzC, the compositions of BzC in the surface-adsorbed film and micelle and three kinds of differential partition coefficients corresponding to phase transitions of the DPPC bilayer membrane were evaluated from thermodynamic analysis of the experimental data. The surface-adsorbed film and micelle were more abundant in BzC than the aqueous solution and significantly large differential partition coefficients for the DPPC membranes were observed. The results clearly showed that the BzC molecules greatly partitioned into hydrophobic environments produced by surfactant-monolayer and phospholipid-bilayer membranes. The partitioning behavior of BzC was also compared with that of charged local anesthetic procaine hydrochloride (PC·HCl). It was shown that the PC·HCl molecule did not or hardly partition into such hydrophobic environments. The contrasting results of the partitioning between BzC and PC·HCl are attributable to the drastic decrease of hydrophilicity of BzC due to the lacking of ionic polar head group in comparison with PC·HCl.

Determination of procaine, benzocaine and tetracaine by sequential injection analysis with permanganate-induced chemiluminescence detection

Local anaesthetics procaine hydrochloride ( I), benzocaine ( II), and tetracaine hydrochloride ( III) were determined by the technique of sequential injection analysis (SIA) with chemiluminescence (CL) detection. The CL was emitted during the oxidation of the analytes by permanganate in aqueous sulphuric acid in the presence of various CL enhancers (4-hydroxybiphenyl, Rhodamine B, glycolaldehyde, glutaraldehyde and formic acid). The optimum enhancer or reagent concentrations, order and volumes of the injected zones were: 0.37 M formic acid (40, 23 or 28 μl for I– III, respectively), sample (40 μl), 2.3 M H 2SO 4 (20, 16 or 18 μl for I– III, respectively), and 0.5 mM KMnO 4 (19, 13 or 15 μl for I– III, respectively). After a double (or single for III) reversal of the flow the mixed zone was pushed into the detector at a flow rate of 100 μl s −1. The transient CL signal was recorded at ≥390 nm. The calibration graphs relating the intensity of the emission (peak heights) to the concentration of the analytes were curvilinear (a second order polynomial showed the best fit) and they were suitable for determining I– III in the ranges 0.5–50, 0.5–25 and 0.2–25 μg ml −1, respectively. The limits of detection (3 σ) were 0.3 μg ml −1 for I and II and 0.1 μg ml −1 for III. The sample throughput was 120 h −1. The relative standard deviations were ≤3.8% ( n=10) when determining 5 μg ml −1 of I– III in prepared pure test solutions. The I and II were assayed in pharmaceutical dosage forms by the proposed method and the SIA results did not show any statistically significant difference from those obtained by standard titrimetry with sodium nitrite.

Effects of anticonvulsants on local anaesthetic-induced neurotoxicity in rats.

The effects of various anticonvulsants on local anaesthetics procaine- and lidocaine-induced convulsions were investigated in rats. Pretreatment with diazepam (2.5-5 mg/kg, intraperitoneally) and clonazepam (5-10 mg/kg, intraperitoneally) completely protected the rats against both local anaesthetic-induced convulsions. Phenobarbital (12.5-50 mg/kg, subcutaneously) also significantly decreased the incidence of both convulsions and prolonged their latencies. Carbabazepine (10-40 mg/kg, intraperitoneally) did not completely repress both convulsions, but it prolonged their latencies. Phenytoin (5-20 mg/kg, intraperitoneally) and primidone (30-60 mg/kg, intraperitoneally) markedly enhanced both local anaesthetic-induced convulsions, as shown by shortening of latency and increase in mortality. Valproate (100-200 mg/kg, intraperitoneally) produced a protective effect against procaine-induced convulsions, while it strongly enhanced lidocaine-induced convulsions. These results suggest that the benzodiazepines are effective drugs to prevent neurotoxicity induced by local anaesthetics, while phenytoin and primidone potentiate them.

Thermal destabilization of transmembrane proteins by local anaesthetics

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 (T m) of denaturation of 61oC which is decreased, for example, to 53oC by 15mMlidocaine. The degree of destabilization (T m) 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 T m for the Ca2+ -ATPase as a function of the concentration of anaesthetic in water gives dissociation constants (K d) on the order of 10-4 M, if binding occurs directly from the aqueous phase. This demonstrates moderate affinity binding. However, dissociation constants of 1-3M 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.

The involvement of the mediodorsal nucleus of the thalamus and the midbrain extrapyramidal area in locomotion elicited from the ventral pallidum

Motor activity is regulated by projections from the nucleus accumbens to the ventral pallidum, but it is unclear which efferents regulate behavioral output from the ventral pallidum. Motor activity was elicited pharmacologically by microinjecting either the mu opioid receptor agonist, Tyr- d-Ala-Gly-NmePhe-Gly-OH (DAMGO) or the glutamate receptor agonist, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA) into the ventral pallidum. The involvement of efferent projections was determined by microinjecting the local anesthetic procaine into the mediodorsal nucleus of the thalamus (MD) or the midbrain extrapyramidal area (MEA) prior to administering DAMGO or AMPA into the ventral pallidum. The motor activity induced by DAMGO was blocked by procaine microinjected into either the MD or the MEA. In contrast, procaine microinjected into the MD did not block motor activity elicited by AMPA while procaine into the MEA abolished the behavioral activation. These data indicate that the involvement of efferent projections from the ventral pallidum to either the MD or MEA in motor activation depends upon the type of receptor stimulated in the ventral pallidum.

The effect of intraseptal procaine injection of hippocampal theta in freely moving cat

Numerous studies have demonstrated that in the rodent, the septum is a critical site for the generation of hippocampla rhythmical field activity (theta, RSA). The aim of the present study was to clarify the role of the medial septal area in theta generation in the cat. Results indicate that (1) the microinfusion of the local anesthetic procaine into the medial septal region temporarily suppressed spontaneous as well as sensory and electrically induced hippocampal theta; (2) the suppression lasted 15 min and then amplitude and power of the hippocampal theta showed a progressive increase reaching preprocaine levels 60 min from the infusion onset. Theta frequency, in contrast, did not differ from control levels. The results provide evidence for the medial septal mediation of the hippocampal theta in the cat. This region is responsible for controlling theta amplitude but not its frequency. The present data supported the earlier results obtained in the rat and determined that the medial septal region plays a critical role in the generation of the hippocampal theta activity in cat.

A comparative study of the scaled vibrational frequencies in the local anesthetics procaine, tetracaine and propoxycaine by means of semiempirical methods: AM1, PM3 and SAM1

AM1, PM3 and SAM1 semiempirical calculations were carried out to obtain the frequencies of the normal modes in several local anesthetics of amino-ester type. The values computed with the three methods were scaled and compared among themselves and with the experimental data. The structural parameters: bond lengths, bond and torsional angles were optimized in the most stable conformation. Several relationships between the parameters of the p-amino group were established. Some general conclusions were drawn

Procain interaction with DPPC multilayers: an ESR spin label investigation

A spin label electron spin resonance (ESR) study has been carried out on the interaction between the local anesthetic procaine (PRC) and multilamellar dispersions of di-palmitoylphosphatidylcholine (DPPC). The investigation has been performed either in the gel or in the liquid crystal phase of DPPC varying the anesthetic/DPPC molar ratio as well as the pH of the dispersion medium and using spin labeled DPPC molecules (5- and 16-PCSL) and the di-tert-butyl nitroxide (DTBN) spin probe. On increasing the anesthetic concentration in the dispersion medium up to PRC/DPPC molar ratio of 33 mol.%, a lyotropic transition of the bilayer from the lamellar gel phase Lβ, to the interdigitated Lβi one is observed either at pH 5.0 or at pH 10.0. At intermediate pH values, about pH 7.0, such a PRC concentration dependent transition is absent. A decrease of the partition of the DTBN molecules between the dispersion medium and the fluid hydrophobic phase of DPPC multilayers is observed at pH 5.0 with anesthetic concentration, while an opposite behaviour is evidenced at pH 10.0. The pre- and main-phase transition temperatures of the DPPC multilayers are also affected although to different extent. These results are interpreted in terms of adsorption of the PRC molecules at the surface of the model membrane at the extreme pH values investigated, while at about neutral pH values they intercalate among the DPPC molecules. The protonation state of procaine plays an important role as it determines the way of surface adsorption of the PRC molecules in the neutral form at the high pH value and in the charged cationic form at pH 5.0.

Cocaine discrimination: relationship to local anesthetics and monoamine uptake inhibitors in C57BL/6 mice.

Although the discriminative properties of cocaine have been examined extensively in rats, and to a lesser extent in other species, there are currently no reports on cocaine discrimination by mice. In one of our experiments, C57BL/6 (C57) mice acquired cocaine discrimination (10 mg/kg training dose) and exhibited dose responsive generalization to lower doses of the drug, which was similar to previous reports using rats. In addition, mazindol, a general monoamine uptake inhibitor similar to cocaine, and nomifensine, which is relatively specific for the dopamine transporter, substituted completely for cocaine, as described for rats. In contrast, there was little substitution evidenced by monoamine uptake inhibitors relatively specific for the norepinephrine transporter (nisoxetine) or for the serotonin transporter (fluoxetine), or by the local anesthetics procaine or lidocaine. In our second experiment, neither cocaine nor mazindol substituted for procaine in animals trained to discriminate the local anesthetic (100 mg/kg) although lidocaine substituted completely for the procaine cue. These experiments emphasize the importance of the dopamine transporter in mediating the discriminative stimulus effects of cocaine in C57 mice. The lack of cross generalization between cocaine and procaine suggests that the anesthetic properties of cocaine contribute little toward its discrimination by this mouse strain.

Effect of procaine on membrane potential and intracellular pH in Xenopus laevis oocytes.

The effect of the local anaesthetic procaine on the intracellular pH, pHi, and electrophysiological properties of full-grown Xenopus oocytes was studied. In spite of its interference with both the pH-sensitive microelectrodes and fluorescent probe BCECF, we have shown that procaine induced an intracellular acidification rather than the alkalization commonly observed in most cells. The resting pHi of Xenopus oocytes loaded with BCECF was 7.36 +/- 0.04 (n = 16). Addition of 10 mM procaine to the bath at pH 7.5 caused pHi to decrease to a new steady state value of 6.97 +/- 0.05 (n = 9). A similar behaviour of pHi was observed with microelectrodes. Procaine also promoted a rise in membrane conductance and a membrane depolarization. These changes in membrane potential and conductance were not caused by the decrease in pHi since the addition of sodium propionate at pH 7.5 produced the same decrease of pHi as procaine, but resulted in only a slight depolarization with superimposed oscillations. Current measurements using two-electrode voltage clamp showed that the depolarization was associated with an inward current. No significant effect on this current was observed when replacing Cl, K or Na in the external medium. The absence of effect of Cl and K channel inhibitors argues against the involvement of Cl and K currents during the procaine response.

Far-Infrared of the Local Anesthetic Procaine

The low spectral region of procaine was studied by far-infrared spectroscopy. Raman lines were registered and interpreted. An equivalent study was performed on the molecule of benzocaine. In the characterization of the bands, and in the description of the torsion-inversion mode of the p-amino group, the AM1 semiempirical method was used. The optimum geometry parameters, the torsion and inversion potential functions, the energy levels, and the transitions were obtained. The effects of temperature on the torsion and inversion modes were studied.

Exclusion of the Local Anesthetic Procaine Hydrochloride from a Surface-Adsorbed Film and Micelle of Decylammonium Chloride

Incorporation of the local anesthetic procaine hydrochloride (PC·HCl) into surface-adsorbed films and micelles formed by decylammonium chloride (DeAC) was investigated by measuring the surface tensions of aqueous solutions of a DeAC−PC·HCl mixture. The thermodynamic quantities of the miscibility in these molecular aggregates, the total surface density, and the compositions of PC·HCl in the surface-adsorbed film and micelle were calculated by applying thermodynamic equations to the surface tension data. The phase diagrams of surface adsorption and micelle formation showed a peculiar feature; namely, the compositions of PC·HCl in the adsorbed film and micelle showed negative values over the whole composition range measured. The negative values were caused by the exclusion of the PC·HCl molecules from the adsorbed film and the micelle of DeAC. PC·HCl was not incorporated into such hydrophobic environments. In contrast, tetracaine hydrochloride (TC·HCl) was incorporated into the adsorbed film and micelle of DeAC at all DeAC−TC·HCl compositions. The difference in incorporation between TC·HCl and PC·HCl is attributable to the hydrophobicity of their molecules.

Raman Spectrum of Procaine Hydrochloride

A vibrational study of the local anesthetic procaine hydrochloride in the solid state and in aqueous solution was carried but. Assignment of the amino groups was performed using deuterated and non-deuterated samples. All the bands in the spectra were identified and assigned. The structure of the procaine cation was determined using the AM 1 semi-empirical method. A comparison with crystallographic data was made. The frequencies and intensities of the vibrations were also computed using AM1. Vibrational scale factors were employed in the AM1 calculations.

Local anesthetics measured by lipophilic β‐cyclodextrin‐based ion‐selective electrodes

Abstract2,3,6‐Trioctyl and 2,6‐didodecyl‐β‐cyclodextrins have been incorporated in ion‐selective electrodes as neutral ionophores for the detection of the local anesthetics procaine, prilocaine, lidocaine and bupivacaine hydrochlorides. Nernstian response and excellent limits of detection were observed (−log [C]≥5.0). Interference from ‘serum’ levels of sodium, potassium and calcium (150.0 mmol dm−3 Na+, 1.26 mmol dm−3 Ca2+ 4.30 mmol dm−3 K+ ), was negligible (−log K,) (overall)≥4.0). The major organic interferents were molecules of similar size and structure which caused reduced slope and drift in baseline potentials at 10 mmol dm−3 levels of concentrations. However, the interferences were substantially reduced when the interferent concentration was reduced by a factor of 10. Nernstian response was maintained in the presence of bovine serum albumin (BSA), serum (HS) and aI acid glycoprotein (AAG). A polyurethane, (Tecoflex SG80) membrane matrix was more biocompatible when compared to PVC as evidenced by lower E0 (internal) shifts with the former.

1905 Capsaicin attenuates the noradrenaline-induced temperature increase in brown adipose tissue in the rat

E series prostaglandins (PGE) are known to elicit potent hyperthermia when injected into the anterior hypothalamic preoptic area (POAH) in rats, but the effector mechanisms mediating the rise in temperature are not well defined. In the present study, microinjection of PGE2 into the POAH dose-dependently increased non-shivering thermogenesis in brown adipose tissue (BAT) in urethananesthetized rats, bringing about a marked and sustained rise in interscapular BAT (IBAT) and core temperatures. The effect of intra-POAH PGE2 injection on IBAT and core temperatures could be blocked by systemic pretreatment with the sympathetic ganglionic blocker chlorisondamine chloride or the β-adrenergic receptor blocker propranolol, thus implicating the involvement of the sympathetic system. Furthermore, the increase in IBAT and core temperatures induced by intra-POAH PGE2 could be blocked by prior injection of the local anesthetic procaine or the GABA receptor agonist muscimol into the ipsilateral ventromedial hypothalamic nucleus (VMH). Taken together, the results suggest that PGE2 increases body temperature by acting in the POAH to stimulate heat production in BAT via a sympathetic efferent mechanism located in the VMH.