Influence of local anesthetics upon human polymorphonuclear leukocyte function in vitro. Reduction of lysosomal enzyme release and superoxide anion production

Persistent pain relief following a single injection of a local anesthetic for neuropathic abdominal wall and groin pain

OBJECTIVES

It is our experience that a small portion of patients with neuropathic abdominal wall pain syndromes such as the anterior cutaneous nerve entrapment syndrome (ACNES) have a long term beneficial response following just one single tender point injection (TPI) with a local anesthetic agent. This report focuses on the phenomenon of ongoing pain relief following a single local anesthetic injection in neuropathic abdominal wall and groin pain syndromes.

METHODS

This report is an overview based on earlier studies from a center of expertise for neuropathic abdominal wall and groin pain syndromes. All studies on neuropathic abdominal wall and groin pain syndromes reporting on efficacy of a diagnostic TPI using a local anesthetic agent were included.

RESULTS

A total of 10 studies including 834 patients fulfilled study criteria. Each of these 10 studies found that approximately 10% (range, 4-25%) of the cases experienced persistent pain relief after a single TPI with lidocaine 1%.

CONCLUSIONS

Persistent pain relief after a single TPI using a local anesthetic agent may be observed in approximately one of 10 patients suffering from neuropathic abdominal wall or groin pain syndromes. When a patient is suspected of having a neuropathic abdominal wall or groin pain syndrome, a single TPI using a local anesthetic agent should be administered as long term pain relief may occasionally occur.

Comparative Analysis of Different Local Anesthetic Solutions Available in Market: An In Vitro and Clinical Study

OBJECTIVES

 The study aimed to evaluate and compare various commercially available local anesthetic solutions.

MATERIALS AND METHODS

 A total of 150 commercially available local anesthetic cartridges of similar composition (2% lidocaine with epinephrine 1:100,000) were randomly collected and divided into 3 groups. The designations of groups were selected from their product names such that each group consisted of 60 cartridges. Group S (Septodont, France) Group M (Medicaine, Korea) and Group H (HD-Caine, Pakistan). The samples were divided into five sub-groups, each consisting of 10 cartridges from each group to investigate each parameter.

RESULTS

 The acquired data was statistically analyzed and compared (using SPSS version 12). Compositional analysis revealed a non-significant (P>0.05) difference when the three Groups were compared with standard lidocaine and epinephrine solutions. The mean pH values of samples from group S, M and H respectively fell within the range of pH values of commercially available solutions. Non-significant difference in EPT values of Group S and H was found when efficacy was compared (p = 0.3), however a significant difference (p < 0.01) was observed in contrast to Group M. Anti-bacterial activity was observed in all the group and a non-significant difference in cell viability values of Group S and M was found (p = 0.6), while the difference was significant in comparison to Group H.

CONCLUSION

 Within the limitations of these investigations, it appears that the properties of different manufacturers fall within the recommended ranges as mentioned in literature and do not appear to be statistically different in the variables we have tested.

Effect of Proparacaine in a Mouse Model of Allergic Rhinitis

Objectives

Lidocaine, a local anaesthetic is a treatment option in uncontrolled asthma due to its immunomodulatory effects. In the present study, proparacaine (PPC), a derivative of lidocaine was examined for its therapeutic application in a mouse model of allergic rhinitis.

Methods

The mice were grouped into 4 groups: control group, allergic rhinitis (AR) group, ciclesonide (CIC) group, and PPC group. Nasal symptom scores, eosinophil counts, goblet cell counts, and mast cells counts in the nasal mucosa were measured. Serum ovalbumin (OVA)-specific immunoglobulin (Ig) E, OVA-specific IgG1, OVA-specific IgG2a, interleukin (IL)-4, IL-5, and cortisol levels were measured.

Results

Intranasal administration of PPC significantly decreased nasal symptoms, number of eosinophils, goblet cells, and mast cells in the lamina propria of the nasal mucosa. Serum OVA-specific IgE, OVA-specific IgG1, OVA-specific IgG2a was significantly higher in the AR compared with the control group. Serum level of IL-4 was significantly lower in the CIC group and PPC group in comparison with AR group. Serum IL-5 showed no significant difference among all groups. No significant difference in serum cortisol levels was observed among the 4 groups.

Conclusion

PPC appears to have a therapeutic potential in treatment of allergic rhinitis in a mouse model by reducing eosinophil, goblet cell, and mast cell infiltration in the nasal mucosa.

Postoperative persistent chronic pain: what do we know about prevention, risk factors, and treatment

BACKGROUND AND OBJECTIVES

Postoperative persistent chronic pain (POCP) is a serious health problem, disabling, undermining the quality of life of affected patients. Although more studies and research have addressed the possible mechanisms of the evolution from acute pain to chronic postoperatively, there are still no consistent data about the risk factors and prevention. This article aims to bring what is in the panorama of the current literature available.

CONTENT

This review describes the definition, risk factors, and mechanisms of POCD, its prevention and treatment. The main drugs and techniques are exposed comprehensively.

CONCLUSION

Postoperative persistent chronic pain is a complex and still unclear etiology entity, which interferes heavily in the life of the subject. Neuropathic pain resulting from surgical trauma is still the most common expression of this entity. Techniques to prevent nerve injury are recommended and should be used whenever possible. Despite efforts to understand and select risk patients, the management and prevention of this syndrome remain challenging and inappropriate.

Pharmacokinetics and pharmacodynamics of lignocaine: A review

Lignocaine is an essential drug on World Health Organisation essential drug list, considered efficacious, safe and cost-effective for any health-care system. Despite its ubiquitous use in medicine and surgery, there are few detailed reviews of its pharmacokinetics and pharmacodynamics. Being an amide-type local anesthetic and Class 1b antiarrhythmic, lignocaine is most frequently used clinically for its anesthetic and antiarrhythmic benefits. However, lignocaine has important antinociceptive, immuno-modulating, and anti-inflammatory properties. Information pertaining to the pharmacokinetics and pharmacodynamics of lignocaine was examined by performing a literature search of PubMed, Embase and MEDLINE (via Ovid), pharmacology textbooks and online sources. We present a focused synopsis of lignocaine’s pharmacological composition, indications for use and mechanisms of action, focusing on its anti-inflammatory, immuno-modulating and analgesia effects. In addition we review the dosing regimes and infusion kinetics of lignocaine in the clinical setting. Finally, we review the evidence for ligocaine’s modulation of the inflammatory response during major surgery and its specific effects on cancer recurrence. These indirect effects of local anesthetics in tumor development may stem from the reduction of neuroendocrine responses to the stress response elicited by major surgery and tissue damage, enhanced preservation of immune-competence, in addition to opioid-sparing effects of modulating tumor growth.

Topical use of Rectogesic® and Emla® to improve cutaneous blood perfusion following thermal injury. A comparative experimental study

Early post-burn ischemic necrosis of the skin is of particular interest in modern burn research. The purpose of this study was to test the hypothesis that blood perfusion could be improved by the topical application of vasoactive substances. A sample of 55 wistar rats was used to investigate the effect of 0,4% nitroglycerin ointment (Rectogesic(®)) comparatively to no application and placebo. The beneficiary action of 5% prilocaine/lidocaine cream (EMLA(®)) in burn blood perfusion was also tested comparatively to Rectogesic(®). Both preparations were tested respectively to non burned controls. Laser Doppler assessment of blood flow at 15, 30, 45, 60, 120 and 180 minutes after preparation application, demonstrated that the use of Rectogesic(®) improved perfusion at all measurements compared to placebo and to no preparation application (p&0,05). There was no statistical significant difference in the effect of the two preparations.

Hyperkalemic cardioplegia for adult and pediatric surgery: end of an era?

Despite surgical proficiency and innovation driving low mortality rates in cardiac surgery, the disease severity, comorbidity rate, and operative procedural difficulty have increased. Today's cardiac surgery patient is older, has a "sicker" heart and often presents with multiple comorbidities; a scenario that was relatively rare 20 years ago. The global challenge has been to find new ways to make surgery safer for the patient and more predictable for the surgeon. A confounding factor that may influence clinical outcome is high K(+) cardioplegia. For over 40 years, potassium depolarization has been linked to transmembrane ionic imbalances, arrhythmias and conduction disturbances, vasoconstriction, coronary spasm, contractile stunning, and low output syndrome. Other than inducing rapid electrochemical arrest, high K(+) cardioplegia offers little or no inherent protection to adult or pediatric patients. This review provides a brief history of high K(+) cardioplegia, five areas of increasing concern with prolonged membrane K(+) depolarization, and the basic science and clinical data underpinning a new normokalemic, "polarizing" cardioplegia comprising adenosine and lidocaine (AL) with magnesium (Mg(2+)) (ALM™). We argue that improved cardioprotection, better outcomes, faster recoveries and lower healthcare costs are achievable and, despite the early predictions from the stent industry and cardiology, the "cath lab" may not be the place where the new wave of high-risk morbid patients are best served.

Anesthetics impact the resolution of inflammation

BACKGROUND

Local and volatile anesthetics are widely used for surgery. It is not known whether anesthetics impinge on the orchestrated events in spontaneous resolution of acute inflammation. Here we investigated whether a commonly used local anesthetic (lidocaine) and a widely used inhaled anesthetic (isoflurane) impact the active process of resolution of inflammation.

METHODS AND FINDINGS

Using murine peritonitis induced by zymosan and a systems approach, we report that lidocaine delayed and blocked key events in resolution of inflammation. Lidocaine inhibited both PMN apoptosis and macrophage uptake of apoptotic PMN, events that contributed to impaired PMN removal from exudates and thereby delayed the onset of resolution of acute inflammation and return to homeostasis. Lidocaine did not alter the levels of specific lipid mediators, including pro-inflammatory leukotriene B(4), prostaglandin E(2) and anti-inflammatory lipoxin A(4), in the cell-free peritoneal lavages. Addition of a lipoxin A(4) stable analog, partially rescued lidocaine-delayed resolution of inflammation. To identify protein components underlying lidocaine's actions in resolution, systematic proteomics was carried out using nanospray-liquid chromatography-tandem mass spectrometry. Lidocaine selectively up-regulated pro-inflammatory proteins including S100A8/9 and CRAMP/LL-37, and down-regulated anti-inflammatory and some pro-resolution peptides and proteins including IL-4, IL-13, TGF-â and Galectin-1. In contrast, the volatile anesthetic isoflurane promoted resolution in this system, diminishing the amplitude of PMN infiltration and shortening the resolution interval (Ri) approximately 50%. In addition, isoflurane down-regulated a panel of pro-inflammatory chemokines and cytokines, as well as proteins known to be active in cell migration and chemotaxis (i.e., CRAMP and cofilin-1). The distinct impact of lidocaine and isoflurane on selective molecules may underlie their opposite actions in resolution of inflammation, namely lidocaine delayed the onset of resolution (T(max)), while isoflurane shortened resolution interval (Ri).

CONCLUSIONS

Taken together, both local and volatile anesthetics impact endogenous resolution program(s), altering specific resolution indices and selective cellular/molecular components in inflammation-resolution. Isoflurane enhances whereas lidocaine impairs timely resolution of acute inflammation.

Evidence-informed management of chronic low back pain with epidural steroid injections

The management of chronic low back pain (CLBP) has proven very challenging in North America, as evidenced by its mounting socioeconomic burden. Choosing amongst available nonsurgical therapies can be overwhelming for many stakeholders, including patients, health providers, policy makers, and third-party payers. Although all parties share a common goal and wish to use limited health-care resources to support interventions most likely to result in clinically meaningful improvements, there is often uncertainty about the most appropriate intervention for a particular patient. To help understand and evaluate the various commonly used nonsurgical approaches to chronic low back pain, the North American Spine Society has sponsored this special focus issue of The Spine Journal, titled Evidence-Informed Management of Chronic Low Back Pain Without Surgery. Articles in this special focus issue were contributed by leading spine practitioners and researchers, who were invited to summarize the best available evidence for a particular intervention and encouraged to make this information accessible to nonexperts. Each of the articles contains five sections (description, theory, evidence of efficacy, harms, and summary) with common subheadings to facilitate comparison across the 24 different interventions profiled in this special focus issue, blending narrative and systematic review methodology as deemed appropriate by the authors. It is hoped that articles in this special focus issue will be informative and aid in decision making for the many stakeholders evaluating nonsurgical interventions for CLBP.

JMF2-1, a lidocaine derivative acting on airways spasm and lung allergic inflammation in rats

BACKGROUND

Prior reports show that nebulized lidocaine might be an effective treatment for asthma.

OBJECTIVE

We sought to determine the anti-inflammatory and spasmolytic effects of lidocaine and its analogue, JMF2-1, which we have synthesized for reduced local anesthetic activity.

METHODS

Blockade of Na(+) currents was assayed in cultured GH(3) cells by using the patch-clamp technique, whereas anesthesia was assessed in a cutaneous pinching test in rats. Lidocaine and its analogue were nebulized into sensitized rats for evaluation of their effectiveness on airways spasm and inflammation induced by methacholine and allergen, respectively. Tissue histamine release and tracheal spasm triggered by allergen challenge in the absence and presence of these treatments were also examined in vitro.

RESULTS

The 50% inhibitory concentration values for blockade of Na(+) currents after treatment with JMF2-1 (25.4 mM) was remarkably higher than that of lidocaine (0.18 mM), which is consistent with the weak anesthetic capacity of this analogue. In contrast, JMF2-1 was more potent than lidocaine in inhibiting allergen-induced histamine release and tracheal spasm. In in vivo settings methacholine-induced increase in lung resistance (145%) significantly reduced to 72% and 47% after lidocaine and JMF2-1 treatment, respectively. Both treatments inhibited by about 81% allergen-evoked eosinophil accumulation into the lung tissue.

CONCLUSION

Replacement of the 2,6-dimethyl radicals by the 2-trifluormethyl group on the benzene ring of lidocaine significantly reduces anesthetic activity, preserving its ability to prevent key aspects of the allergic inflammatory response in the lung.

CLINICAL IMPLICATIONS

Nebulized JMF2-1 might be a means of achieving the antiasthmatic effects of lidocaine without the anesthetic effects.

Local anesthetic-induced protection against lipopolysaccharide-induced injury in endothelial cells: the role of mitochondrial adenosine triphosphate-sensitive potassium channels

Lidocaine attenuates cell injury induced by ischemic-reperfusion and inflammation, although the protective mechanisms are not understood. We hypothesized that lidocaine and other amide local anesthetics protect against endothelial cell injury through activation of the mitochondrial adenosine triphosphate-sensitive potassium (mitoK(ATP)) channels. We determined the effects of amide local anesthetics (lidocaine, ropivacaine, and bupivacaine), ester local anesthetics (tetracaine and procaine), one amide analog (YWI), and two non-amide local anesthetic analogs (JDA and ICM) on viability of human microvascular endothelial cells after exposure to lipopolysaccharide (LPS) in the absence or presence of the mitoK(ATP) channel antagonist 5-hydroxydecaonate. Flavoprotein fluorescence was used to investigate the effects of local anesthetics on diazoxide-induced activation of mitoK(ATP) channels. Lidocaine, ropivacaine, bupivicaine, YWI, JDA, and ICM attenuated by 60% to 70% the decrease in cell viability caused by LPS. Amide local anesthetics and YWI protection was inhibited by 5-hydroxydecaonate, whereas the protection induced by JDA and ICM was not. Tetracaine and procaine did not protect against LPS-induced injury. The amide local anesthetics and the amide analog (YWI) enhanced diazoxide-induced flavoprotein fluorescence by 5% to 20%, whereas ester local anesthetics decreased diazoxide-induced flavoprotein fluorescence by 5% to 60% and the non-amide local anesthetic analogs had no effect. In conclusion, amide local anesthetics and the amide analog (YWI) attenuate LPS-induced cell injury, in part, through activation of mitoK(ATP) channels. In contrast, tetracaine and procaine had no protective effects and inhibited activation of mitoK(ATP) channels. The non-amide local anesthetic analogs induced protection but through mechanisms independent of mitoK(ATP) channels.

Anti-inflammatory properties of local anesthetics and their present and potential clinical implications

Development of new local anesthetic agents has been focused on the potency of their nerve-blocking effects, duration of action and safety and has resulted in a substantial number of agents in clinical use. It is well established and well documented that the nerve blocking effects of local anesthetics are secondary to their interaction with the Na+ channels thereby blocking nerve membrane excitability and the generation of action potentials. Accumulating data suggest however that local anesthetics also possess a wide range of anti-inflammatory actions through their effects on cells of the immune system, as well as on other cells, e.g. microorganisms, thrombocytes and erythrocytes. The potent anti-inflammatory properties of local anesthetics, superior in several aspects to traditional anti-inflammatory agents of the NSAID and steroid groups and with fewer side-effects, has prompted clinicians to introduce them in the treatment of various inflammation-related conditions and diseases. They have proved successful in the treatment of burn injuries, interstitial cystitis, ulcerative proctitis, arthritis and herpes simplex infections. The detailed mechanisms of action are not fully understood but seem to involve a reversible interaction with membrane proteins and lipids thus regulating cell metabolic activity, migration, exocytosis and phagocytosis.

Lidocaine attenuates cytokine-induced cell injury in endothelial and vascular smooth muscle cells

Local anesthetics have been reported to attenuate the inflammatory response and ischemia/reperfusion injury. Therefore, we hypothesized that pretreatment with local anesthetics may protect endothelial and vascular smooth muscle (VSM) cells from cytokine-induced injury. Human microvascular endothelial cells and rat VSM cells were pretreated with lidocaine or tetracaine (5-100 microM for 30 min) and then exposed to the cytokines tumor necrosis factor-alpha, interferon-gamma, and interleukin-1beta for 72 h. Cell survival and integrity were evaluated by trypan blue exclusion and lactate dehydrogenase release. The role of adenosine triphosphate-sensitive potassium (KATP) channels, protein kinase C, or both in modulating local anesthetic-induced protection was evaluated with the mitochondrial KATP antagonist 5-hydroxydecanoate, the cell-surface KATP antagonist 1-[5-[2-(5-chloro-o-anisamido)ethyl]-2-methoxyphenyl]sulfonyl-3-methylthiourea (HMR-1098), and the protein kinase C inhibitor staurosporine. Lidocaine attenuated cytokine-induced cell injury in a dose-dependent manner. Lidocaine (5 microM) increased cell survival by approximately 10%, whereas lidocaine (100 microM) increased cell survival by approximately 60% and induced a threefold decrease in lactate dehydrogenase release in both cell types. In contrast, tetracaine did not attenuate cytokine-induced cell injury. 5-hydroxydecanoate abolished the protective effects of lidocaine, but staurosporine and HMR-1098 had no effect on the lidocaine-induced protection. This study showed that lidocaine, but not tetracaine, attenuates cytokine-induced injury in endothelial and VSM cells. Lidocaine-induced protection appears to be modulated by mitochondrial KATP channels.

IMPLICATIONS

This study demonstrates that lidocaine attenuates cytokine-induced injury of endothelial and vascular smooth muscle cells via mechanisms involving adenosine triphosphate-sensitive potassium channels. Protection of the vasculature from cytokine-induced inflammation may preserve important physiological endothelial and vascular smooth muscle functions.

Pharmacologic prevention of posterior capsule opacification: in vitro effects of preservative-free lidocaine 1% on lens epithelial cells

PURPOSE

To assess the in vitro effectiveness of preservative-free lidocaine 1% in removing lens epithelial cells (LECs) from the anterior capsule and to evaluate the effect of lidocaine on the LECs.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Eight rabbits (16 eyes) were used in the study. After the rabbits were killed, the eyes were enucleated and divided into 2 groups. In Group 1 (n = 8 eyes), LECs were exposed to preservative-free lidocaine 1% or balanced salt solution (BSS) for 1, 2, or 5 minutes. The anterior capsules were then stained with trypan blue and alizarin red. Photomicrographs of each capsule were taken and analyzed for LEC damage. In Group 2 (n = 8 eyes), hydrodissection was performed with 1 of the agents, followed by phacoemulsification and cortical cleanup. The LEC attachment to the anterior capsule was evaluated by histopathology.

RESULTS

Anterior capsule fragments irrigated with BSS showed no LEC nuclear staining; ie, no direct toxic effect. In those irrigated with preservative-free lidocaine 1%, the LECs showed mild toxicity; some cells showed blue nuclear staining. After hydrodissection with lidocaine, the capsules were almost free of LECs; after hydrodissection with BSS, the capsules showed a normal layer of LECs attached to the anterior capsule.

CONCLUSIONS

Preservative-free lidocaine 1% may help diminish the amount of live LECs by facilitating cortical cleanup, by loosening the desmosomal area of cell-cell adhesion with decreased cellular adherence, or by a direct toxic effect. The use of this agent may help prevent posterior capsule opacification.

Effects of tetracaine and bupivacaine on chemiluminescence generated by formyl-methionyl-leucyl-phenylalanine-stimulated human leukocytes and cell-free systems

We investigated the abilities of an ester-type local anesthetic tetracaine and an amide-type local anesthetic bupivacaine to inhibit reactive oxygen and/or nitrogen species generated by either human leukocytes or cell-free systems via luminol- and lucigenin-enhanced chemiluminescence (CL). Tetracaine (96+/-1%, n=6, 1 mM) and bupivacaine (97+/-0.4%, n=5, 1 mM) significantly inhibited FMLP-induced-CL in leukocyte assay. In cell-free experiments, CL due to superoxide production was significantly inhibited by tetracaine (23+/-2%, n=6) and bupivacaine (25+/-4%, n=6) at 1 mM. Although bupivacaine was ineffective on H(2)O(2)-induced CL, tetracaine activated H(2)O(2)-induced luminol CL. Additionally, tetracaine inhibited FeSO(4)-induced CL (42+/-2%, n=6, 1 mM). In hypochlorous acid (HOCl)-induced CL assay, 70+/-10% (n=5) and 57+/-4% (n=15) inhibitions were observed by tetracaine and bupivacaine, respectively. Peroxynitrite-induced luminol (54+/-7%, n=7, tetracaine, and 26+/-5%, n=8, bupivacaine, at 1 mM) and lucigenin CL (58+/-3%, n=6, tetracaine, and 22+/-14%, n=9, bupivacaine, at 1 mM) were markedly inhibited. Tetracaine interacted with superoxide, hydroxyl radical, HOCl and peroxynitrite, while bupivacaine scavenged superoxide, HOCl and peroxynitrite. These direct scavenging properties of these drugs might be involved in the inhibition observed in leukocyte free radical release. In general, a decrease in CL-response was seen with higher concentrations (0.1-1 mM) of the local anesthetics, it is likely that tetracine and bupivacaine at therapeutic concentrations do not suppress leukocyte function in vivo.

Therapeutic spinal corticosteroid injections for the management of radiculopathies

Current literature and a recent meta-analysis suggest a favorable role for corticosteroid injections in the nonoperative treatment of radiculopathy [70]. The superior results reported in recent literature may be attributable to precise fluoroscopically guided transforaminal placement of injectate close to the disc-nerve root interface and near the dorsal root ganglia, maximizing the therapeutic effect. The favorable results of corticosteroid injections in the treatment of radiculopathy caused by a focal disc herniation are consistent with the biochemical construct of radicular pain. The preliminary unfavorable results of therapeutic SNRB for radicular pain caused by epidural or intraneural fibrosis or occurring after trauma may relate to a biomechanical rather than a biochemical etiology. Outcomes for acquired cervical or lumbar spinal stenosis are intermediate compared with those observed for herniated discs and scarring or trauma. Such results may stem from the multifactorial origin of stenosis symptoms; they may develop from impaired venous flow, restricted neural glide, inflammation, or structural root injury. Better-designed studies that use strict inclusion criteria that stratify patients into categories according to the mechanism of injury (atraumatic versus traumatic), the presence or absence of neurologic deficits or imaging abnormalities, and prior treatment will provide the basis for evidence-based treatment decisions. Such an emphasis is just beginning and inevitably will occur. Until then, decisions have to be predicated on the limited and flawed work conducted to date [71]. Nevertheless, the information gleaned from these published reports provides valuable insight not available just a decade ago.

Lidocaine inhibits secretion of IL-8 and IL-1beta and stimulates secretion of IL-1 receptor antagonist by epithelial cells

Lidocaine and related local anaesthetics have been shown to be effective in the treatment of ulcerative colitis (UC). However, the mechanisms underlying their therapeutic effect are poorly defined. Intestinal epithelial cells play an important role in the mucosal inflammatory response that leads to tissue damage in UC via the secretion of pro-inflammatory cytokines and chemokines. The aim of this study was to evaluate the direct immunoregulatory effect of lidocaine on pro-inflammatory cytokine and chemokine secretion from intestinal epithelial cells. HT-29 and Caco-2 cell lines were used as a model system and treated with lidocaine and related drugs. The expression of IL-8, IL-1beta and the IL-1 receptor antagonist (RA) were assessed by ELISA and quantification of mRNA. In further experiments, the effect of lidocaine on the secretion of IL-8 from freshly isolated epithelial cells stimulated with TNFalpha was tested. Lidocaine, in therapeutic concentrations, inhibited the spontaneous and TNFalpha-stimulated secretion of IL-8 and IL-1beta from HT-29 and Caco-2 cell lines in a dose-dependent manner. Similarly, suppression of IL-8 secretion was noted in the freshly isolated epithelial cells. Other local anaesthetics, bupivacaine and amethocaine, had comparable effects. Lidocaine stimulated the secretion of the anti-inflammatory molecule IL-1 RA. Both the inhibitory and the stimulatory effects of lidocaine involved regulation of transcription. The results imply that the therapeutic effect of lidocaine may be mediated, at least in part, by its direct effects on epithelial cells to inhibit the secretion of proinflammatory molecules on one hand while triggering the secretion of anti-inflammatory mediators on the other.

Inhibitory effects of S-(-) and R-(+) bupivacaine on neutrophil function

BACKGROUND

Local anesthetics inhibit migration, enzyme release and superoxide anion generation of polymorphonuclear leukocytes (PMN). Due to their ability to phagocytose and kill bacteria PMN represent a major defense mechanism in the circulating blood. In this study we determined the influence of racemic bupivacaine and its enantiomers on neutrophil phagocytic activity, oxidative burst as well as surface expression of complement and Fcgamma receptors.

METHODS

Venous blood was pre-incubated with different concentrations of either racemic bupivacaine, R-(+) or S-(-) bupivacaine. Fluoresceine isothiocyanate (FITC)-labeled antibodies against Fcgamma receptor III (CD16), complement receptor 1 (CD35) and complement receptor 3 (CD11b) were used to determine surface receptor expression. Phagocytic activity was measured by ingestion of FITC-labeled vital Staphylococcus aureus. Oxidative burst was determined by conversion of nonfluorescent dihydrorhodamine 123 into fluorescent rhodamine 123. Fluorescent intensity of each sample was determined by flow cytometry.

RESULTS

Racemic bupivacaine inhibited surface receptor expression, phagocytosis, and oxidative burst in a time- and concentration-dependent manner. Although the S-(-) enantiomer exerted significantly less inhibitory action on neutrophil function compared to R-(+) and racemic bupivacaine, these effects were small compared to the overall changes.

CONCLUSION

These findings suggest that bupivacaine impairs surface receptor expression and may thereby contribute to reduced phagocytic activity and oxidative burst. Enantiomer-specific effects of bupivacaine may play a minor role in the inhibition of these leukocyte functions.

Effects of local anesthetics on phospholipase D activity in differentiated human promyelocytic leukemic HL60 cells

Local anesthetics impair certain functions of neutrophils, and phospholipase D (PLD) is considered to play an important role in the regulation of these functions. To understand the mechanisms by which local anesthetics suppress the functions of neutrophils, we examined the effects of local anesthetics on PLD in neutrophil-like differentiated human promyelocytic leukemic HL60 cells. Tetracaine, a local anesthetic, inhibited formyl-methionyl-leucyl-phenylalanine (fMLP)- and 4beta-phorbol 12-myristate 13-acetate (PMA)-induced PLD activation, but potentiated fMLP-stimulated phospholipase C activity. All four local anesthetics tested suppressed PMA-induced PLD activation to different extents, and the order of their potency was tetracaine > bupivacaine > lidocaine > procaine. In a cell-free system, tetracaine suppressed guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS)-induced PLD activation as well as PMA-induced PLD activation. Western blot analysis revealed that tetracaine prevented the membrane translocation of PLD-activating factors, ADP-ribosylation factor, RhoA, and protein kinase Calpha. Tetracaine also inhibited the activity of recombinant hPLD1a in vitro. These results suggest that local anesthetics suppress PLD activation in differentiated HL60 cells by preventing the membrane translocation of PLD-activating factors, and/or by directly inhibiting the enzyme per se. Therefore, it could be assumed that local anesthetics would suppress the functions of neutrophils by inhibition of PLD activation.

Digital image analysis of erythema development after experimental thermal injury to human skin: effect of postburn topical local anesthetics (EMLA)

Local anesthetics inhibit edema and improve circulation in experimental burns. We evaluated the effect of topical local anesthetics on human skin burns in volunteers using computerized color analysis that allowed repeated noninvasive quantitative measurements. A standardized partial-thickness burn (1 cm2) was induced in one forearm of 10 healthy volunteers and in the opposite forearm a week later. The burned areas were treated with lidocaine/prilocaine cream (EMLA; Astra, Sweden) or a placebo cream for 1 h. The experimental skin area was photographed before and 1, 2, 4, and 12 h postburn. Digitized images were evaluated using normalized red-green-blue and Hue-Saturation-Intensity. Differences in erythema between skin treated with EMLA and placebo were not significant during the first 4 h postburn. However, 12 h postburn, a pronounced decrease in the degree of erythema was observed in EMLA-treated skin compared with placebo-treated skin. We conclude that topical local anesthetics administered for 1 h postburn significantly reduces the duration of erythema after a mild thermal injury, which suggests a potential use in clinical practice in the treatment of minor skin burns.

IMPLICATIONS

Burn injury constitutes a serious type of tissue damage that activates inflammatory mechanisms, often causing pain, disfiguration, or malfunction. We treated burns using an anesthetic cream and demonstrated a reduction in burn-induced inflammation by using computer-based color image analysis.

Effects of lidocaine on nucleus pulposus-induced nerve root injury. A neurophysiologic and histologic study of the pig cauda equina

STUDY DESIGN

Application of autologous nucleus pulposus on nerve roots and treatment with local application of lidocaine in the pig.

OBJECTIVES

Studies of the effects of lidocaine on nucleus pulposus-exposed nerve roots.

SUMMARY OF BACKGROUND DATA

Nerve root infiltration may improve radicular symptoms beyond the pharmacologic duration of local anesthetics, but the mechanisms for this effect are not known.

METHODS

Nucleus pulposus was harvested from a lumbar disc and placed onto the sacrococcygeal cauda equina in pigs. In Series 1, early lidocaine treatment of nucleus pulposus-induced nerve root injury, pigs received 2% lidocaine (n = 5) or saline (n = 5) before and after surgery. Nerve conduction velocity and histologic appearance were studied after 3 days. In Series 2, delayed lidocaine treatment of nucleus pulposus-induced nerve root injury, after 7 days 2% lidocaine was administered epidurally to nucleus pulposus-exposed (n = 4) and -nonexposed (n = 4) nerve roots. Nerve conduction velocity, muscle action potentials, and histologic appearance were assessed.

RESULTS

In Series 1, early treatment with lidocaine limited the reduction in nerve conduction velocity. The epidural inflammation was less in lidocaine treated animals. In Series 2, nerve conduction velocity was lower in nucleus pulposus-exposed animals than in nonexposed animals. The initial reduction of nerve conduction velocity and muscle action potential was similar between the groups, but the recovery of muscle action potential was slower and less complete in nucleus pulposus-exposed nerve roots. There was minimal histologic nerve injury in both series and in both protocols.

CONCLUSIONS

Early treatment with lidocaine may reduce nucleus pulposus-induced nerve root injury. Lidocaine induced a delayed recovery in nerve roots exposed to nucleus pulposus. Further studies are needed to clarify the therapeutic effects of nerve root infiltration and the pathophysiology of nucleus pulposus-induced nerve root injury.

Topical local anaesthetics (EMLA) inhibit burn-induced plasma extravasation as measured by digital image colour analysis

Amide local anaesthetics have previously been shown to reduce oedema and improve dermal perfusion following experimental burns. Previous studies have used invasive techniques for burn oedema quantification which do not allow continuous monitoring in the same animal. The present study used digital image colour analysis to investigate the effect of topical local anaesthetics on burn-induced extravasation of Evans blue albumin. A standardised full-thickness burn injury (1 x 1 cm) was induced in the abdominal skin of anaesthetised rats. The burn area was subsequently covered with 0.5 g of lidocaine-prilocaine cream 5% (25 mg of each in 1 g; EMLA, ASTRA, Sweden) or placebo cream during the first hour post-burn. One hour after the burn trauma, animals received Evans blue dye intravenously. Skin colour appearances were recorded by macrophotography before the burn and 5, 60. 65, 90, 120, 150, and 180 min post-burn. Colour slides were digitised and colour changes were analysed using the normalised red-green-blue (n-rgb) colour system. Results showed a significant inhibition of Evans blue extravasation between 60 and 180 min post-burn in EMLA-treated animals versus controls. Topical local anaesthetics are potent inhibitors of burn-induced plasma albumin extravasation, probably by direct action on vascular permeability and by inhibition of various steps of the pathophysiological response after burn injury.

Lidocaine and its Analogues Inhibit IL-5-Mediated Survival and Activation of Human Eosinophils

Eosinophils and cytokines active on eosinophils, especially IL-5, are believed to be critically involved in chronic allergic diseases. IL-5 activates eosinophils and enhances their survival in vitro by delaying apoptosis. In this study, we found that lidocaine and six analogues blunt responses of eosinophils to IL-5. Lidocaine and its derivatives inhibit IL-5-mediated eosinophil survival in a concentration-dependent manner (IC50 = 110 μM for 30 pg/ml IL-5). At suboptimal lidocaine concentrations, the eosinophil survival response to IL-5 shifts and more IL-5 is required to maintain survival. The inhibitory effect requires at least 24-h exposure of eosinophils to lidocaine, and the protein kinase C activator, PMA, completely reverses the inhibition. A multiparameter flow-cytometric analysis shows that lidocaine hastens the apoptosis of eosinophils normally delayed by IL-5. Lidocaine does not affect IL-5R expression or IL-5-induced protein tyrosine phosphorylation. Lidocaine also inhibits eosinophil survival mediated by IL-3 or granulocyte-macrophage CSF, although less potently than that mediated by IL-5. Furthermore, lidocaine inhibits eosinophil superoxide production stimulated by IL-5, granulocyte-macrophage CSF, or IL-3, but not that stimulated by platelet-activating factor, immobilized IgG, or PMA. Lidocaine and its derivatives show novel immunomodulatory properties and are able to blunt eosinophil responses to cytokines in addition to their local anesthetic or antiarrhythmic properties. Thus, lidocaine and its derivatives may represent a new class of therapeutic agents to treat patients with allergic diseases.

Adverse effects and drug interactions associated with local and regional anaesthesia

Systemic and localised adverse effects of local anaesthetic drugs usually occur because of excessive dosage, rapid absorption or inadvertent intravascular injection. Small children are more prone than adults to methaemoglobinaemia, and the combination of sulfonamides and prilocaine, even when correctly administered, should be avoided in this age group. The incidence of true allergy to local anaesthetics is rare. All local anaesthetics can cause CNS toxicity and cardiovascular toxicity if their plasma concentrations are increased by accidental intravenous injection or an absolute overdose. Excitation of the CNS may be manifested by numbness of the tongue and perioral area, and restlessness, which may progress to seizures, respiratory failure and coma. Bupivacaine is the local anaesthetic most frequently associated with seizures. Treatment of CNS toxicity includes maintaining adequate ventilation and oxygenation, and controlling seizures with the administration of thiopental sodium or benzodiazepines. Cardiovascular toxicity generally begins after signs of CNS toxicity have occurred. Bupivacaine and etidocaine appear to be more cardiotoxic than most other commonly used local anaesthetics. Sudden onset of profound bradycardia and asystole during neuraxial blockade is of great concern and the mechanism(s) remains largely unknown. Treatment of cardiovascular toxicity depends on the severity of effects. Cardiac arrest caused by local anaesthetics should be treated with cardiopulmonary resuscitation procedures, but bupivacaine-induced dysrhythmias may be refractory to treatment. Many recent reports of permanent neurological complications involved patients who had received continuous spinal anaesthesia through a microcatheter. Injection of local anaesthetic through microcatheters and possibly small-gauge spinal needles results in poor CSF mixing and accumulation of high concentrations of local anaesthetic in the areas of the lumbosacral nerve roots. In contrast to bupivacaine, the hyperbaric lidocaine (lignocaine) formulation carries a substantial risk of neurotoxicity when given intrathecally. Drugs altering plasma cholinesterase activity have the potential to decrease hydrolysis of ester-type local anaesthetics. Drugs inhibiting hepatic microsomal enzymes, such as cimetidine, may allow the accumulation of unexpectedly high (possibly toxic) blood concentrations of lidocaine. Reduction of hepatic blood flow by drugs or hypotension will decrease the hepatic clearance of amide local anaesthetics. Special caution must be exercised in patients taking digoxin, calcium antagonists and/or beta-blockers.

Neuroendocrine stress hormones do not recreate the postoperative hypercoagulable state

Surgery causes changes in hemostasis, leading to a hypercoagulable state that has been linked to both arterial and venous thrombotic complications. The etiology of this state is unknown, but many investigators have hypothesized that perioperative neuroendocrine changes are responsible. We have previously demonstrated minimal increases in hemostatic function with a stress hormone infusion. This study was undertaken to further examine the relationship between neuroendocrine hormones and hemostatic function. Seventeen healthy volunteers were administered a stress hormone cocktail i.v. (epinephrine, cortisol, glucagon, angiotensin II, and vasopressin) for 24 h in a blind, placebo-controlled, cross-over design in our clinical research center. Venous blood samples were obtained for measurement of hemostatic function before the infusion and at 2, 8, and 24 h. There were no demonstrable increases in any measure of hypercoagulability. Alternatively, there was an increase in tissue plasminogen activator and protein C activity. These changes are consistent with an inhibition of coagulation and improved fibrinolysis. These data suggest that this combination of neuroendocrine hormones is not responsible for the postoperative hypercoagulable state.

IMPLICATIONS

Infusion of five stress hormones (epinephrine, cortisol, glucagon, vasopressin, and angiotensin II) to normal volunteers does not cause increases in procoagulant proteins and platelet reactivity or decreases in fibrinolytic proteins. Alternatively, these five hormones caused increased levels of fibrinolytic proteins (tissue plasminogen activator) and endogenous anticoagulants (protein C antigen and activity).

The inhibitory effects of local anesthetics on superoxide generation of neutrophils correlate with their partition coefficients

Lidocaine and tetracaine suppress superoxide anion (O2-) generation of neutrophils. We examined the effects of eight local anesthetics on O2- generation in human neutrophils and searched for a potential relationship between the biological activities and the physicochemical properties of presently available eight local anesthetics. Human neutrophils incubated with local anesthetic and a Cypridina luciferin analog as a O2(-)-specific chemiluminescence probe were stimulated by phorbol ester. The chemiluminescence development based on O2- generation was monitored by a luminometer. All of the tested local anesthetics suppressed O2- generation in a concentration-dependent manner. The concentration of each of eight local anesthetics that produced 50% inhibition of peak chemiluminescence (IC50) had a rank order of dibucaine < tetracaine < bupivacaine < ropivacaine < procaine < mepivacaine < lidocaine = prilocaine. A linear relationship was obtained between IC50 values and the values of logarithm of partition coefficient (log P) of eight local anesthetics; log (IC50 in molarity) = -1.252 - 0.514 x log P, r2 = 0.891, P < 0.001. Unlike with staurosporine, which inhibits protein kinase C (PKC), no effect was observed on the O2- generation in the presence of tetrodotoxin (TTX), veratridine (VTD), or amiloride. These results suggest that the inhibitory effects of local anesthetics on O2- generation of neutrophils are predicted by physicochemical properties of the drugs, especially partition coefficients.

Leukocyte hydrogen peroxide production in a surgical wound in mice. The effects of an amide local anaesthetic

The oxygen metabolism of polymorphonuclear leukocytes (PMN) is of importance in local tissue repair processes. Amide local anaesthetics are commonly used to relieve surgical wound pain. The cellular effects of local anaesthetics in vivo is poorly described in the literature. However, interactions between amide local anaesthetics and the oxygen metabolism of leukocytes have been reported. To extend that knowledge, this paper investigates the influence of lidocaine treatment on the production of hydrogen peroxide (H2O2) by leukocyte oxygen metabolism. A soft tissue chamber model in the mouse was used, allowing measurements of the H2O2 production spontaneously and after phorbol myristate acetate (PMA) addition, from two different leukocyte pools. Exudate leukocytes were generally more reactive to PMA stimulation in comparison to tissue chamber adherent leukocytes. Topically administered lidocaine significantly influenced the number of leukocytes in the wound exudate at 24 h postoperatively. Exudate leukocytes, topically exposed to lidocaine, showed an enhanced H2O2 production in comparison to leukocytes receiving lidocaine systemically. At 6 days, the viability and the H2O2 production differed significantly between the group receiving topically applied lidocaine in comparison to placebo. We conclude that the wound healing process may be effected by topically applied lidocaine, administered in clinical doses, at least via interference with leukocyte oxygen metabolism.

Preoperative wound infiltration with bupivacaine reduces early and late opioid requirement after hysterectomy

We conducted a randomized, double-blind trial to evaluate the early and late analgesic effect of preoperative wound infiltration with bupivacaine 0.25% (40 mL) compared to placebo (NaCl 0.9%, 40 mL) in patients undergoing major surgery. Forty-one patients scheduled for elective hysterectomy during general anesthesia were included. The pain management focused on pain prevention, including preoperative administration of nonsteroidal antiinflammatory drugs (NSAIDs), and peroperative administration of opioids. Postoperatively patients received buprenorphine and/or acetaminophen on demand. A significant difference between treatments was evident in the 3-day postoperative trial period. With identical pain scores in the two groups, the requested total amount of buprenorphine was greater in the placebo group (2.0 [0-5.1] mg) (median and [range]) than in the bupivacaine group (0.8 [0-2.8] mg) (P < 0.05). The demand for analgesics occurred earlier in those who received placebo (225 min) than in those who received bupivacaine (345 min), but did not reach the level of significance. In conclusion, preoperative wound infiltration with bupivacaine improved immediate and late postoperative pain management after hysterectomy compared to placebo.

Lidocaine attenuates the hypotensive and inflammatory responses to endotoxemia in rabbits

OBJECTIVE

To assess the effects of lidocaine on the hemodynamic and inflammatory responses to Escherichia coli endotoxemia in rabbits.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

University laboratory.

SUBJECTS

Twenty-seven female Japanese rabbits, anesthetized with urethane and ventilated mechanically.

INTERVENTIONS

Animals were randomly assigned to one of three groups: a) endotoxemic control group (n = 9), receiving intravenous Escherichia coli endotoxin (0.5 mg/kg bolus) via the mesenteric vein; b) laparotomy control group (n = 9), treated identically to the endotoxemic control group, except for substitution of 0.9% saline for endotoxin; and c) lidocaine-treated group (n = 9), treated identically to the endotoxemic controls and additionally, intravenous lidocaine (3 mg/kg bolus, followed by infusion at 2 mg/kg/hr) was administered immediately after endotoxin

MEASUREMENTS AND MAIN RESULTS

We compared hemodynamics, blood gases, and microscopic findings of lung tissue obtained at necropsy in each group. Laparotomy alone had a minimal effect on the parameters and findings. Endotoxin injection decreased mean systolic arterial pressure from 135 +/- 6 (SD) to 95 +/- 25 mm Hg (p < .05) and increased the mean base deficit from -1.2 +/- 1.8 to -14.4 +/- 4.2 mmol/L (p < .05), and caused the infiltration of neutrophils into the lungs. Lidocaine administration abolished the hypotension and attenuated the increase the base deficit to -9.5 +/- 2.1 mmol/L (p < .05) and the cellular infiltration in comparison with endotoxemic controls.

CONCLUSIONS

Lidocaine attenuated the hemodynamic and inflammatory responses to endotoxemia in rabbits. Findings suggest that lidocaine administration may prevent the development of hypotension and metabolic acidosis during endotoxemia.

Lidocaine reduces reperfusion injury and neutrophil migration in canine lung allografts

BACKGROUND

Depletion of neutrophils (PMNs) and inhibition of PMN endothelial adhesion ameliorate post-ischemic lung reperfusion injury. Lidocaine reduces PMN adhesion to endothelial surfaces in vivo, and inhibits upregulation of PMN-CD11b/CD18 (Mac-1) in vitro. We evaluated the effect of lidocaine on reperfusion injury, PMN adhesion, and PMN migration in preserved lung allografts.

METHODS

Donor lungs were flushed with modified Euro-Collins solution (4 degrees C) after prostaglandin E1 administration (250 micrograms), inflated with 550 mL (inspired oxygen fraction = 1.0), and stored for 24 hours at 1 degree C. Left lung allotransplantation was performed in 13 mongrel dogs. Immediately after reperfusion the recipient right pulmonary artery and bronchus were ligated to permit assessment of allograft function during a 6-hour postreperfusion period. Allograft gas exchange (every 15 minutes) and hemodynamics (every 60 minutes) were assessed. Peripheral blood PMN CD11b expression was determined by flow cytometry. After sacrifice allograft bronchoalveolar lavage fluid PMN count and allograft tissue myeloperoxidase activity were measured. Two groups were studied: In group I (n = 8) lidocaine hydrochloride was added to the donor flush (20 mg/L) solution. In addition lidocaine was given to the recipient at the time of thoracotomy (intravenous bolus of 4 mg/kg) followed by a continuous infusion of 4 mg/kg/h during implantation and the assessment period. Three dogs that did not reach effective lidocaine blood levels at the time of reperfusion (3 to 4 micrograms/mL) were excluded from analysis. Group II animals (n = 5) received no lidocaine.

RESULTS

Gas exchange in group I was superior throughout the assessment period (p < 0.05). Bronchoalveolar lavage fluid PMN count in group I was reduced (0.36 x 10(6)PMN/mL versus 6.2 x 10(6) PML/mL; p < 0.03). Group I allograft myeloperoxidase activity was 0.17 U/mg/min compared with 0.28 U/mg/min in group II (p < 0.01). In lidocaine-treated animals PMN CD11b expression was maintained at basal levels 2 hours after reperfusion, compared with group II, in which upregulation of CD11b was observed. Lower lobe wet/dry ratio was not different in the two groups.

CONCLUSIONS

Our observations indicate that lidocaine reduces reperfusion injury and inhibits PMN adhesion and subsequent migration to the lung allograft.

Neutrophil activation during cardiopulmonary bypass in paediatric and adult patients

It has been reported that the 'systemic inflammatory' response occurring during cardiopulmonary bypass (CPB) may be responsible for postoperative complications. This inflammatory response is triggered by the platelet coagulation system, complement activation, resulting in neutrophil activation and degranulation. The aim of this study was to quantify the specific markers of neutrophil activation in the adult and paediatric patient during CPB. We report that neutrophil myeloperoxidase (MPO) and human neutrophil elastase (HNE) are significantly increased in both the paediatric and adult patients. This study utilized enzymatic assays that quantified the enzymatic activity in the blood circulation rather than measurement of the enzyme protein complex. Increased concentrations of MPO were, in part, related to the blood prime with the paediatric patients and the HNE concentrations were related to time on CPB in both the paediatric and adult patient. This study demonstrated that there are significantly elevated neutrophil enzyme activities in the CPB patient and underscores the pivotal role of the neutrophil in the pathophysiology of CPB.

Efficacy of lipid soluble, membrane-protective agents against hydrogen peroxide cytotoxicity in cardiac myocytes

We examined the efficacy of a group of drugs that stabilize the cell membrane and can potentially prevent cytotoxicity in cultured fetal chick cardiac myocytes exposed to hydrogen peroxide (H2O2). The effects of various membrane-protective agents were determined by analysis of the kinetics of lactic dehydrogenase (LDH) release. The kinetic parameters calculated from the data include a rate constant for release of LDH (kb) and the fraction of total LDH that is released from the cells (CIIMax). The CIIMaxs derived from a range of H2O2 concentrations reveal that the mean toxic concentration of H2O2 is 1.1 mM and that the pattern of toxicity is consistent with the damage being directly proportional to the concentration of the free radicals generated from the H2O2. Maximum nontoxic concentrations of three amphiphilic membrane protective agents had no effect upon cytotoxicity from H2O2. The slightly polar lipophilic agent, Trolox C, a vitamin E derivative, was also without protective effect at a maximum nontoxic concentration. The highly lipophilic agent, probucol, had a small protective effect at 50 microM, the maximum concentration we succeeded in solubilizing in the culture medium. However, the lipophilic 21-aminosteroid U74500, delivered to the cells in an emulsion, markedly reduced cytotoxicity from H2O2. The CII Max was significantly reduced and the protection was concentration dependent over a range of concentrations from 50-400 nmol/ml. Furthermore, the inhibition by U74500 was fully consistent with a mechanism of scavenging of free radicals formed during lipid peroxidation. In support of this hypothesis, a dose of 400 nmoles/ml completely prevented an increase in lipid peroxides due to H2O2 exposure, whereas there was a sixfold increase during exposure to H2O2 in untreated myocytes. Thus, a lipid soluble 21-aminosteroid prevented lipid peroxidation and reduced cardiac myocyte injury during exposure to H2O2, probably by scavenging of free radicals formed during lipid peroxidation in the cell membrane, whereas amphiphilic agents, which probably altered the physicochemical structure of the cell membrane but did not scavenge free radicals, were not protective.

Ketamine inhibits contractile responses of intestinal smooth muscle by decreasing the influx of calcium through the L-type calcium channel

During the inflammatory response, tissues release histamine (H), substance P, serotonin (5-HT), prostaglandins and kinins, agents that mediate manifestations of inflammation such as pain, vasodilation, increased capillary permeability and smooth muscle contraction. In this study we investigated whether racemic (R[+]) ketamine (K) and its isomers are spasmolytic on intestinal smooth muscle contracted by inflammatory mediators, and whether the spasmolytic effect of K is related to changes in calcium influx through the L-type calcium channel or to an interaction of K with opioid receptors. We measured the contractions of guinea-pig ileum mounted in an organ bath containing Tyrode's solution gassed with 95% O2/5% CO2 at 37 degrees C. In the first protocol we determined the effect of K and its isomers on contractions induced by five mediators: 10(-7) M H, 10(-8) M substance P, 10(-8) M neurokinin A, 5 x 10(-9) M bradykinin and 5 x 10(-7) M 5-HT. For each of these mediators, we plotted concentration-response curves for the inhibitory effect of K, and from regression fitting of these curves, we calculated the IC50 concentration of K that inhibited the contraction by 50%). In the second protocol we measured the contraction induced by the calcium ionophore A23187 (5.0 x 10(-6) M), both alone and after 1.8-7.2 x 10(-4) M R(+/-)K. Then we examined how the inhibition caused by R(+/-)K was affected by increases in the concentration of extracellular calcium by adding calcium (1.8-7.2 x 10(-3) M).(ABSTRACT TRUNCATED AT 250 WORDS)

Topical ketamine inhibits albumin extravasation in chemical peritonitis in rats

BACKGROUND

As ketamine has local anaesthetic actions and local anaesthetics are known to have anti-inflammatory effects, ketamine could be expected to be an anti-inflammatory agent. Here we sought to determine whether ketamine is indeed anti-inflammatory in chemical peritonitis induced by HCl in rats.

METHODS

Peritonitis was elicited by applying 0.02 M HCl on the surface of the cecum or appendix and quantified by measuring the extravasation of intravenously injected Evan's Blue bound to albumin extracted from those tissues. Three experimental sets were performed. In the first set, four groups of 10 rats each received: 1%, 2%, and 4% ketamine and 1% lidocaine. In the same animal, before induction of peritonitis one area was topically pre-treated with 0.9% saline (control site) and another area was topically pre-treated with 1%, 2% or 4% ketamine or 1% lidocaine (experimental site). In the second set, two groups of 10 rats each received: 2% ketamine or 1% lidocaine. Ten min after the induction of peritonitis, the control site was topically treated with 0.9% saline, while the experimental site was treated with 2% ketamine or 1% lidocaine. In the third set 20 rats, divided into two groups, were pre-treated either with 2% S(+)ketamine or 2% R(-)ketamine before the induction of peritonitis instead of the previously employed racemic version of the drug.

RESULTS

Treatment of the cecum or appendix areas with ketamine or lidocaine before the induction of peritonitis decreased the extravasation of Evan's Blue-albumin from 5.7 +/- 0.7 micrograms/100 mg tissue to 4.5 +/- 0.8, N.S. with 1% ketamine; from 5.9 +/- 0.8 to 4.1 +/- 0.7, P < 0.01 with 2% ketamine; from 4.8 +/- 0.7 to 3.5 +/- 0.6, P < 0.05 with 4% ketamine and from 5.9 +/- 0.6 to 3.6 +/- 0.8, P < 0.01 with 1% lidocaine. Treatment of the areas of peritonitis with 2% ketamine or 1% lidocaine decreased the extravasation of Evan's Blue-albumin from 5.6 +/- 0.5 micrograms/100 mg tissue to 4.4 +/- 0.6, P < 0.05 and from 6.0 +/- 0.8 to 5.0 +/- 0.7, P < 0.01. Administration of the isomer S(+)ketamine to colonic areas before the induction of peritonitis reduced the extravasation of Evan's Blue-albumin from 6.5 +/- 0.7 micrograms/100 mg tissue to 4.1 +/- 0.6, P < 0.01; while the isomer R(-)ketamine was inactive.

CONCLUSIONS

These results indicate that topically applied ketamine inhibited the development of chemical peritonitis. This action of racemic ketamine was due to the isomer S(+)ketamine.

Effects of five amino-amide local anaesthetic agents on human polymorphonuclear leukocytes measured by chemiluminescence

The aim of this study was to assess the influence of five amino-amide local anesthetic agents on the production of oxygen metabolites in the human polymorphonuclear leukocyte (PMNL), both intra- and extracellularly. Ropivacaine, a new long-acting amino-amide local anaesthetic agent, bupivacaine, lidocaine, mepivacaine and prilocaine in concentrations 1-5 micrograms.ml-1 up to 500-1000 micrograms.ml-1 were compared to an untreated control. PMNLs were isolated from heparinized blood (healthy adult volunteers). Cells were incubated with the various local anaesthetics (37 degrees C, 30 min), then placed in a Biolumat (luminol-amplified chemiluminescence) and stimulated by formyl-methionyl-leucyl-phenylalanine (FMLP), phorbol myristate acetate (PMA) or ionomycin. Horseradish peroxidase (HRP) was added to discriminate between an intra- or extracellular response. In general, a decrease in chemiluminescence-response was seen with higher concentrations (500-1000 micrograms.ml-1) of the various local anaesthetics. Lidocaine showed a decrease even at lower concentrations. A marked increase in intracellular response for prilocaine 1000 micrograms.ml-1 (3894 mumol.l-1) accompanied by a reduction in extracellular response, using FMLP +/- HRP as a stimuli, was noted. Ropivacaine 1000 micrograms.ml-1 (3216 mumol-l-1) showed a decrease both intra- and extracellularly that was similar to, and even somewhat more pronounced than lidocaine 1000 micrograms.ml-1 (3692 mumol.l-1), when using PMA with or without HRP as the stimuli.

Neuronal involvement in the intestinal effects of Clostridium difficile toxin A and Vibrio cholerae enterotoxin in rat ileum

BACKGROUND/AIMS

Activation of intestinal mast cells and neurons is involved in intestinal inflammation and diarrhea. This study compared the effects of neuronal inhibitors and inhibition of intestinal sensory afferent nerves on the intestinal actions of Clostridium difficile toxin A, an inflammatory enterotoxin, and cholera toxin, a noninflammatory enterotoxin.

METHODS

The effects of lidocaine, hexamethonium, atropine, and long-term pretreatment of capsaicin on fluid secretion, mannitol permeability, myeloperoxidase (MPO) activity, and release of rat mast cell protease II (RMCPII) were measured in toxin A- and cholera toxin-exposed loops in vivo.

RESULTS

Lidocaine, hexamethonium, and capsaicin, but not atropine, inhibited toxin A-mediated secretion and MPO activity, but only capsaicin reduced mannitol permeability. Lidocaine, but not capsaicin, reduced secretion and permeability caused by cholera toxin. Toxin A caused release of RMCPII from rat ileum in vivo and in vitro; this was inhibited by lidocaine or capsaicin, whereas cholera toxin had no effect on release of RMCPII.

CONCLUSIONS

Neuronal mechanisms are important in the in vivo effects of these two enterotoxins. Capsaicin-sensitive sensory afferent neurons and mast cells are involved in the intestinal mechanism of toxin A, but not cholera toxin.

Preoperative infiltration of the surgical area enhances postoperative analgesia of a combined low-dose epidural bupivacaine and morphine regimen after upper abdominal surgery

In a randomized, blinded trial we assessed the value of adding preoperative infiltration of the surgical area with bupivacaine to a low dose epidural regimen for postoperative pain treatment. Forty-nine patients scheduled for major upper abdominal surgery during combined thoracic epidural (bupivacaine + morphine) and general anaesthesia were studied. Postoperative analgesia was epidural bupivacaine 10 mg/hr-1 + morphine 0.2 mg/hr-1 for 72 h. The patients randomly received preoperative infiltration of the surgical area with bupivacaine 0.25%, 40 ml (group I); or no infiltration (group II). Pain was evaluated at rest, during cough and during mobilization six and eight h after start of surgery, and at 8 a.m. and 4 p.m. on the following days until 72 h after start of surgery. The sensory level of analgesia was evaluated by pin prick. We found no difference between the two groups during rest and cough. However, during mobilization group I had lower pain scores compared to group II (P < 0.05). There was a significant reduction in the need for supplemental intramuscular morphine in the treatment group compared to the control group (P < 0.05). Thus an enhanced analgesic effect was demonstrated by adding preoperative infiltration of the surgical area with local anaesthetic to a low dose epidural bupivacaine/morphine regimen after upper abdominal surgery.

Impairment of raw 264.7 macrophage function by antiarrhythmic drugs

The effect of the antiarrhythmic drugs lidocaine, quinidine and procainamide on macrophage function was investigated in RAW 264.7 mouse monocytic macrophage cell. Cells stimulated by either zymosan or phorbol ester were found to generate both superoxide (O2-) and H2O2. The production of O2 was detected as superoxide dismutase inhibitable ferricytochrome c reduction. H2O2 production was monitored in both chemical and flow cytometric fluorescent assays. Although all three drugs inhibited both O2 and H2O2 release in a dose-dependent manner, only quinidine was found to have significant inhibitory effects. The amounts of quinidine required to cause a 50% inhibition in O2 production in zymosan and phorbol ester stimulated cells were found to be 250 microM and 300 microM, respectively and the amounts required to cause one-half optimum levels of H2O2 production in these cells were found to be 50 microM and 100 microM, respectively. The effect of these drugs on O2 producing NADPH oxidase was investigated and only procainamide was found to have a significant effect (p < 0.001) in inhibiting the oxidase activity. Lidocaine and quinidine had no significant effect on the activation of the respiratory burst oxidase. A sensitive and convenient 'differential phagocytosis' assay was devised on the basis of number of particles engulfed by individual phagocytes using flow cytometric techniques. It appears to be remarkably free of interference and was applied to investigate the role of antiarrhythmic drugs on the phagocytosis of fluorescent latex beads. All three antiarrhythmic drugs inhibited phagocytosis of latex beads in a dose dependent manner irrespective of the number of particles phagocitized by the cells. The results of these studies do not conclusively establish a mechanism of action of these drugs on the generation of O2 and H2O2 by stimulated macrophages; nevertheless, it is interesting that all three drugs inhibited the phagocytic activity.

Lidocaine inhibits priming and protein tyrosine phosphorylation of human peripheral neutrophils

The addition of agents, such as tumor necrosis factor-alpha, to human peripheral neutrophils (HPPMN) induces priming, which enhances the receptor-mediated superoxide (O2-) generation and tyrosine phosphorylation of several HPPMN proteins. Lidocaine, a local anesthetic, inhibited both enhanced O2- generation and tyrosine phosphorylation of a 115 kDa protein in a concentration- and time-dependent manner. Lidocaine also inhibited protein kinase C sensitive O2- generation induced by phorbol myristate acetate, but not time dependently. Furthermore, lidocaine inhibited O2- generation by non-primed HPPMN induced by formylmethionyl-leucyl-phenylalanine, but this inhibition needed a higher concentration of lidocaine compared with that of primed HPPMN. These results suggest that lidocaine inhibits the priming step of neutrophil activation and that it is linked to the inhibition of tyrosine phosphorylation of a 115 kDa protein.

Modification of neutrophil functions by naftifine

Naftifine (NF), a topical antimycotic agent, is highly active in vitro and in vivo against a wide range of pathogenic fungi. NF inhibits human polymorphonuclear leucocyte (PMN) chemotaxis. Following stimulation with zymosan-activated serum, 85-97% of the PMNs exhibited detectable membrane ruffling and polarity. In contrast, NF-treated PMNs did not exhibit such chemotactic factor-induced shape changes. We also analysed the effect of NF on PMN superoxide anion (O2-) and chemiluminescence (CL) production, as a measure of respiratory burst activity. Stimulation of PMNs pre-incubated with NF (37 degrees C for 30 min at 1-150 micrograms/ml) by FMLP, PMA and zymosan resulted in a dose-dependent inhibition in PMN CL. Doses of NF which depressed chemotaxis, inhibited CL and diminished O2- production in a statistically significant manner (P < 0.05-0.001). In conclusion, NF alters membrane-related responses in PMNs, and this alteration may be associated with a change in PMN morphology. Binding of NF to PMN membrane sterol, with a subsequent alteration in membrane configuration, is the most likely cause of the inhibition of PMN function. The data collectively document biochemical and morphological differences between control and NF-treated PMNs as determined by stimulus-specific CL and O2- generation and membrane shape change. Such differences may account, in part, for its efficacy in inflammatory fungal skin diseases.

Inhibitory effects of amide local anaesthetics on stimulus-induced human leukocyte metabolic activation, LTB4 release and IL-1 secretion in vitro

The anti-inflammatory effects of the amide local anaesthetics lidocaine and bupivacaine were evaluated in vitro by examination of the metabolic activation and secretory responses of human polymorphonuclear granulocytes (PMNGs) and mononuclear cells. Pretreatment with lidocaine or bupivacaine had a dose-dependent inhibitory effect on PMNG luminol-amplified chemiluminescence stimulated by bovine serum albumin (BSA)/anti-BSA immune complexes (IC) or by serum-opsonized zymosan (SOZ) particles. Both lidocaine and bupivacaine inhibited the release of the inflammatory mediators leukotriene B4 (LTB4) and interleukin-1 (IL-1) evaluated by radioimmunoassay (RIA). Pretreatment of suspended PMNGs and monocytes with the anaesthetics caused a marked inhibition of LTB4 release when the cells were stimulated with SOZ. In short-term (24 h) cultures of mononuclear cells the addition of lidocaine or bupivacaine reduced, in a dose-dependent manner, the level of IL-1 detected after stimulation with lipopolysaccharide (LPS). In all three assays (chemiluminescence, LTB4 and IL-1 RIA) bupivacaine was found to be more potent than lidocaine. The present results show that amide local anaesthetics have marked suppressive effects on the metabolic activation and secretory functions of leukocytes stimulated by different agonists. Although the detailed mechanisms for these effects are not known, they may explain part of the potent anti-inflammatory actions of local anaesthetics previously described in vivo.