Complete essential oils of Laurus nobilisinducing antinociceptiveaction by opioid mechanism in C-Reflex and spinal Wind-Up model in rat / Aceites esenciales totales de Laurus nobilis inducen acción antinociceptivamediante mecanismo opioide en el modelode Reflejo-C y Wind-Up espinal en ratas

The essential oil of Laurus nobilis L. was used to test their antinociceptive efficacy. It was applied intraperitoneally (i.p.) to rats subjected to a nociception test (C reflex and spinal wind-up). The results showed that the essential oil applied at higher doses (0.06 mg/Kg) causes a complete abolition of the spinal wind-up, while the C reflex was unchanged, indicating a clear antinociceptive effect. At lower concentrations (0.012 mg/Kg), there was a lowering in the wind-up by 85% within ten minutes of the essential i.p. oil application. Interestingly, there was an effect of naloxone (0.08 mg/Kg i.p.) When applied, a change occurs that almost entirely reversed the antinociception caused by the essential oil from Laurus nobilis. We conclude that there is a significant antinociceptive effect of the essential oil of Laurus nobilis subjected to electric nociception. In addition, it was observed that naloxone reversed the antinociceptive effect (wind-up) produced by Laurus nobilis.

El aceite esencial de Laurus nobilis L. se usó para probar su eficacia antinociceptiva. Se aplicó por vía intraperitoneal (i.p.) a ratas sometidas a una prueba de nocicepción (reflejo-C y wind-up espinal). Los resultados mostraron que el aceite esencial aplicado a dosis más altas (0.06 mg/Kg) abolió completamente el wind-up espinal, mientras que el reflejo-C no cambió, lo que indica un claro efecto antinociceptivo. A concentraciones más bajas (0.012 mg/Kg), hubo una disminución en el wind-up en un 85% dentro de los diez minutos del i.p. la aplicación del aceite esencial. Curiosamente, hubo un efecto de la naloxona (0.08 mg/Kg i.p.) la cual revierte casi por completo la antinocicepción causada por el aceite esencial de Laurus nobilis. Concluimos que existe un efecto antinociceptivo significativo del aceite esencial de Laurus nobilis sometido a nocicepción eléctrica. Además, se observó que la naloxona revirtió el efecto antinociceptivo (wind-up) producido por Laurus nobilis.

Local analgesic effect of tramadol is not mediated by opioid receptors in early postoperative pain in rats / O efeito analgésico de tramadol não é mediado por receptores opioides na dor de ratos no pós-operatório imediato / El efecto analgésico del tramadol no está mediado por receptores opiáceos en el dolor en ratones en el postoperatorio inmediato

BACKGROUND AND OBJECTIVES: Tramadol is known as a central acting analgesic drug, used for the treatment of moderate to severe pain. Local analgesic effect has been demonstrated, in part due to local anesthetic-like effect, but other mechanisms remain unclear. The role of peripheral opioid receptors in the local analgesic effect is not known. In this study, we examined role of peripheral opioid receptors in the local analgesic effect of tramadol in the plantar incision model. METHODS: Young male Wistar rats were divided into seven groups: control, intraplantar tramadol, intravenous tramadol, intravenous naloxone-intraplantar tramadol, intraplantar naloxone-intraplantar tramadol, intravenous naloxone-intravenous tramadol, and intravenous naloxone. After receiving the assigned drugs (tramadol 5 mg, naloxone 200 µg or 0.9% NaCl), rats were submitted to plantar incision, and withdrawal thresholds after mechanical stimuli with von Frey filaments were assessed at baseline, 10, 15, 30, 45 and 60 min after incision. RESULTS: Plantar incision led to marked mechanical hyperalgesia during the whole period of observation in the control group, no mechanical hyperalgesia were observed in intraplantar tramadol group, intraplantar naloxone-intraplantar tramadol group and intravenous naloxone-intraplantar tramadol. In the intravenous tramadol group a late increase in withdrawal thresholds (after 45 min) was observed, the intravenous naloxone-intravenous tramadol group and intravenous naloxone remained hyperalgesic during the whole period. CONCLUSIONS: Tramadol presented an early local analgesic effect decreasing mechanical hyperalgesia induced by plantar incision. This analgesic effect was not mediated by peripheral opioid receptors. .

JUSTIFICATIVA E OBJETIVOS: Tramadol é conhecido como um fármaco analgésico de ação central, usado para o tratamento de dor moderada a grave. O efeito analgésico local foi demonstrado, em parte devido ao efeito semelhante ao anestésico local, mas outros mecanismos permanecem obscuros. O papel dos receptores opioides periféricos no efeito analgésico local não é conhecido. Neste estudo, examinamos o papel dos receptores opioides periféricos no efeito analgésico local de tramadol em modelo de incisão plantar. MÉTODOS: Ratos Wistar, jovens e machos, foram divididos em sete grupos: controle, tramadol intraplantar, tramadol intravenoso, tramadol intraplantar-naloxona intravenosa, tramadol intraplantar-naloxona intraplantar, tramadol intravenoso-naloxona intravenosa e naloxona intravenosa. Após receber os medicamentos designados (5 mg de tramadol, 200 mg de naloxona ou NaCl a 0,9%, os ratos foram submetidos à incisão plantar e os limiares de retirada após estímulos mecânicos com filamentos de von Frey foram avaliados no início do estudo e nos minutos 10, 15, 30, 45 e 60 após a incisão. RESULTADOS: A incisão plantar levou à hiperalgesia mecânica acentuada durante todo o período de observação no grupo controle; hiperalgesia mecânica não foi observada nos grupos tramadol intraplantar, tramadol intraplantar-naloxona intraplantar e tramadol intraplantar-naloxona intravenosa. No grupo tramadol intravenoso, um aumento tardio do limiar de retirada (após 45 minutos) foi observado. Os grupos tramadol intravenoso-naloxona intravenosa e naloxona intravenosa permaneceram hiperalgésicos durante todo o período. CONCLUSÕES: Tramadol apresentou efeito analgésico local inicial e diminuiu a hiperalgesia mecânica induzida pela incisão plantar. Esse efeito analgésico não foi mediado por receptores opioides periféricos. .

JUSTIFICACIÓN Y OBJETIVOS: Al tramadol se le conoce como un medicamento analgésico de acción central usado para el tratamiento del dolor moderado a intenso. El efecto analgésico local quedó demostrado, en parte, a causa del efecto similar al del anestésico local, pero otros mecanismos permanecen sin clarificar. El rol de los receptores opiáceos periféricos en el efecto analgésico local no se conoce. En este estudio, examinamos el papel de los receptores opiáceos periféricos en el efecto analgésico local del tramadol en un modelo de incisión plantar. MÉTODOS: Ratones Wistar, jóvenes y machos, fueron divididos en 7 grupos: control, tramadol intraplantar, tramadol intravenoso, tramadol intraplantar-naloxona intravenosa, tramadol intraplantar-naloxona intraplantar, tramadol intravenoso-naloxona intravenosa, y naloxona intravenosa. Después de recibir los medicamentos designados (5 mg de tramadol, 200 µg de naloxona o NaCl al 0,9%), los ratones fueron sometidos a la incisión plantar, y los umbrales de retirada de la pata posteriores a los estímulos mecánicos con filamentos de von Frey fueron evaluados al inicio del estudio y en los minutos 10, 15, 30, 45 y 60 después de la incisión. RESULTADOS: La incisión plantar conllevó hiperalgesia mecánica acentuada durante todo el período de observación en el grupo control; la hiperalgesia mecánica no fue observada en los grupos tramadol intraplantar, tramadol intraplantar-naloxona intraplantar, y tramadol intraplantar-naloxona intravenosa. En el grupo tramadol intravenoso, fue observado un aumento tardío del umbral de retirada (después de 45 min); los grupos tramadol intravenoso-naloxona intravenosa y naloxona intravenosa permanecieron hiperalgésicos durante todo el período. CONCLUSIONES: El tramadol presentó un efecto analgésico local inicial, disminuyendo la hiperalgesia mecánica inducida por la incisión plantar. Ese efecto analgésico no fue mediado por receptores opiáceos periféricos. .

[Gabapentin effect on visceral pain and its interaction with antinociceptive effect of morphine in mice]

Visceral pain is one of the most common forms of pain which requires new therapeutical drugs. The aim of this study is to investigate the inhibitory effect of gabapentin on induced abdominal contractions and to examine the effect of its co- administration with morphine. In this study, 96 mice received acetic-acid intraperitoneally after administration of saline, gabapentin [1, 5, 10, 50 and 100 mg/ kg], morphine [0.25, 0.5, 1, 3 and 5 m/g kg] or a combination of subanalgesic dose of morphine with subanalgesic and the lowest effective dose of gabapentin. In one group naloxone [5mg/kg/i.p] was injected 20 minutes prior to the injection of acetic acid. Then the number of writhes were counted for 45 minutes. Both gabapentin and morphine reduced writhing in a dose-dependent manner. The number of writhes decreased significantly by gabapentin [50 and 100/ mg/kg] and morphine [0.5, 1, 3, 5 mg/kg] comparing to the control group [P<0.001]. Also, the sub-analgesic dose of morphine [0.25mg/kg] with sub-analgesic and low effective dose of gabapentin [50mg/kg and 10mg/kg, respectively] significantly decreased the number of writhes [P<0.005]. The combination of low effective dose of gabapentin [50mg/kg] and sub-analgesic dose of morphine decreased the number of writhings by 94% as compared to the controls [P<0.005]. The antinociceptive effect of combinational administration was not reversed by naloxone [opioid antagonist]. These data demonstrated the comparable efficacy of gabapentin [50 and 100/ mg/ kg; i.p.] with 0.5mg/kg morphine in visceral pains. Also the combination of subanalgesic doses of gabapentin and morphine, which were ineffective alone, produced significant analgesic effect in writhing model of pain. Therefore, combination of low doses of morphine and gabapentin, due to lower rate of side effects, may be clinically considered as a safer treatment in the management of visceral pains

Additive Antinociception between Intrathecal Sildenafil and Morphine in the Rat Formalin Test

The possible characteristics of spinal interaction between sildenafil (phosphodiesterase 5 inhibitor) and morphine on formalin-induced nociception in rats was examined. Then the role of the opioid receptor in the effect of sildenafil was further investigated. Catheters were inserted into the intrathecal space of male Sprague-Dawley rats. For induction of pain, 50 microliter of 5% formalin solution was applied to the hindpaw. Isobolographic analysis was used for the evaluation of drug interaction between sildenafil and morphine. Furthermore, naloxone was intrathecally given to verify the involvement of the opioid receptor in the antinociception of sildenafil. Both sildenafil and morphine produced an antinociceptive effect during phase 1 and phase 2 in the formalin test. The isobolographic analysis revealed an additive interaction after intrathecal delivery of the sildenafil-morphine mixture in both phases. Intrathecal naloxone reversed the antinociception of sildenafil in both phases. These results suggest that sildenafil, morphine, and the mixture of the two drugs are effective against acute pain and facilitated pain state at the spinal level. Thus, the spinal combination of sildenafil with morphine may be useful in the management of the same state. Furthermore, the opioid receptor is contributable to the antinocieptive mechanism of sildenafil at the spinal level.

Successful treatment of intrathecal morphine overdose.

A 47-year-old woman was diagnosed with secondary progressive multiple sclerosis, and was treated with intrathecal morphine for chronic pain via a slow-release subcutaneous pump. She accidentally received a 35-ml (510 mg) bolus injection of morphine by this route, which led to status epilepticus. She was treated with continuous intravenous naloxone infusion, and with medication to control hypertension and stop the seizure activity. The outcome was excellent, and the patient returned to her neurological baseline. This report describes the complications and the successful treatment of intrathecal morphine overdose. In order to prevent these serious errors, it is vital that only care providers who are proficient with these devices perform the refilling procedure.

Enkephalinergic involvement in substantia nigra in the modulation of hypothalamically-induced predatory attack behavior.

The present study was carried out in five cats which did not attack the rats spontaneously. Predatory attack on an anaesthetized rat was elicited by electrical stimulation of lateral hypothalamus at a mean current strength of 650 microA. The attack was accompanied by minimal affective display and culminated in neck biting. Microinfusions of DAME (delta-alanine methionine enkephaline) in 500 ng dose in substantia nigra facilitated the predatory attack and there was a significant reduction in the threshold current strength for affective display as well as somatomotor components. Microinfusions of naloxone, an opioid antagonist in 1.0 microg dose when DAME effect was at its peak reversed the facilitatory effects and the threshold returned to the control levels within 10 minutes of naloxone infusion at the same locus. Microinfusions of naloxone alone in similar dosage completely blocked the predatory attack response as indicated by an increase in the threshold current strength for somatomotor as well as affective display components. The somatomotor were completely inhibited and could not be elicited even when the current strength was increased to 1000 microA. Control injections of saline in similar volumes (0.5 microl) failed to produce any response Microinfusions of naloxone in lower dose (250 ng) failed to produce any blocking effect. These findings indicate that hypothalamically elicited predatory attack is facilitated by enkephalinergic mechanisms operating at the midbrain level.

Bloqueos del neuroeje en cirugía cardíaca / Central neuroaxial blocks in cardiac surgery

El anestésico ideal para la cirugía cardíaca debe ofrecer, además de estabilidad hemodinámica intraoperatoria, una recuperación postanestésica libre de dolor. La utilización de narcóticos en altas dosis se acerca a este ideal. Los bloqueos del neuroeje son una alternativa a los narcóticos en altas dosis. La efectividad de la morfina por vía intratecal o de la analgesia epidural torácica para controlar el dolor postoperatorio está demostrada más allá de toda duda. Esta analgesia es muy necesaria no sólo para confort del paciente sino por una multitud de factores; entre ellos, para disminuir la frecuencia y la severidad de episodios isquémicos postoperatorios así como la cantidad de complicaciones pulmonares y la utilización de drogas vasodilatadoras en el postoperatorio inmediato. El principal problema asociado al uso de morfina por vía intratecal es la depresión respiratoria, que tiene una incidencia de entre el 0.36 y el 1.9 por ciento. Esta depresión está relacionada con la dosis y es fácilmente tratada con naloxona sin abolir el efecto analgésico. Administrar morfina por vía intratecal es técnicamente más fácil y menos costoso, pero la analgesia epidural torácica se puede usar por varios días, no se necesita utilizar opioides, y, al emplearse anestésicos locales, tiene efectos muy beneficiosos sobre la circulación coronaria. La posibilidad de hematoma espinal es cierta y ha impedido la utilización de estos bloqueos, pero ha habido numerosos reportes acerca del uso de morfina por vía intratecal o analgesia epidural torácica involucrando miles de pacientes sin consecuencias adversas. Algunas precauciones son necesarias: agujas ultrafinas, no más de dos intentos para la morfina por vía intratecal y colocación del catéter epidural 20 horas antes de la operación. La utilización de morfina por vía intratecal o analgesia epidural torácica le da grandes beneficios a los pacientes en términos de disminución de complicaciones cardíacas y pulmonares. El riesgo potencial de un hematoma espinal es real, pero probablemente muy sobreestimado, y requiere más estudio.

Effects of chronic systemic administration of opioid peptides, naloxone and N-acetyl beta-endorphin antiserum on gonadotropins and testicular functions in the rat.

Systemic administration of opioid peptides, methionine-enkephalin and beta-endorphin, chronically, lowered gonadotropin levels in plasma and had an inhibitory effect mainly on the testicular enzymes hyaluronidase, acid phosphatase and on incorporation of 3[H] thymidine in the tissue. When rats were similarly treated with opioid peptide antagonist naloxone and N-acetyl beta-endorphin antiserum, induced an opposite effect. This is either the direct effect of opioid peptides/antagonist on the gonads or it may be via the circulating levels of gonadotropin.

Disminución del daño tisular inducido por la obstrucción intestinal experimental con nalozona y sylfóxido de dimetilo en perros / Use of naloxone and dimethyl sulfoxide to decrease tissue damage due to experimental intestinal obstruction in dogs

Después de la corrección de una obstrucción intestinal se producen radicales libres derivados del oxígeno, que se forman durante la isquemia y la reperfusión del área (síndrome de reperfusión). Para valorar hasta qué punto puede resolverse una obstrucción intestinal contrarrestando estos factores con medicamentos, se indujo una obstrucción intestinal a nivel del yeyuno en 10 perros, que se mantuvo durante 120 minutos. A los 110 minutos se administró una combinación de sulfóxido de dimetilo y naloxona con el objetivo de evaluar su eficacia para contrarrestar los efectos de la reperfusión. Los perros de dividieron en dos grupos de 5 animales cada uno: grupo testigo y grupo experimental. Al primer grupo se le administró solución salina fisiológica en cantidad equivalente al volumen administrado de fármacos que se les aplicó al segundo grupo, a este último se le suministró la combinación sulfóxido de dimetilo (a dosis de 1 g/kg de peso a una dilución de 10 por ciento) y naloxona (a dosis de 0.04 mg/kg de peso). Los resultados sugieren que dicha combinación puede ser eficaz para disminuir las lesiones provocadas por los radicales libres, también es eficaz para mejorar la condición del sujeto, al contrarrestar los efectos sistémicos de la reperfusión

Studies on the effect of intratesticular administration of opioid peptides, naloxone or N-acetyl beta-endorphin antiserum on some testicular parameters in rats.

Opioid peptides have been localized in a variety of peripheral tissues like placenta, thyroid, pancreas, gastrointestinal tract, in the reproductive tract of male and female and in the testes of rats. Immunoassayable material was detected in extracts of gonads, reproductive tract and accessory reproductive organs. Studies with naloxone have suggested that beta-endorphin may have an important role in steroidogenesis and may have a role in regulating transport of luminal material. In our studies met-enkephalin, beta-endorphin, naloxone or N-acetyl beta-endorphin antiserum were microinjected intra testicularly once on alternate days for one week and autopsied 24 h after the last injection. Intratesticular administration of 25, 50 and 100 micrograms doses of naloxone induced significant decrease in in vitro secretion of testosterone per se, which was significantly greater with 50 micrograms dose than with those of the other two doses. A 25 micrograms dose had no effect on hyaluronidase or acid phosphatase activity while 50 micrograms dose significantly decreased the enzyme activity. One hundred micrograms dose also significantly decreased hyaluronidase activity. Intratesticular injection of 10 micrograms met-enkephalin or 1 microgram beta-endorphin significantly decreased hyaluronidase activity whereas 20 microliters N-acetyl beta-endorphin antiserum increased the specific activity of hyaluronidase. There was no change in the weight of the testes on treatment with the above agents.

Role of midbrain ventro-lateral tegmental area (VTA) enkephalinergic mechanisms in the facilitation of hypothalamically-induced predatory attack behaviour.

Bipolar concentric electrodes were implanted in five cats in extreme lateral regions of hypothalamus. These sites were electrically stimulated using biphasic square wave pulses at a current strength ranging from 300-800 microA to evoke predatory attack on an anaesthetized but live rat. At lower current strength (300 microA) only alertness with pupillary dilatation was produced. Gradual increase in the current strength led to the recruitment of somatic and affective components and a predatory attack was exhibited at a mean current strength of 700 microA. A scoring system allowed the construction of stimulus response curves, which remained fairly constant when repeated over a period of 3-4 weeks. Bilateral microinjections of delta-alanine methoinine enkephaline (DAME) (500 ng in 0.5 microliter saline) in ventrolateral tegmental area (VTA) elevated the mean threshold current strength for affective components while somatomotor components were totally inhibited. The blocking effect of DAME persisted for 1 hour. Microinjections of naloxone (1 microgram) in similar volumes facilitated the response as indicated by a reduction in threshold current strength for somatomotor and affective components. Microinjections of naloxone (1 microgram) in similar volumes facilitated the response as indicated by a reduction in threshold current strength for somatomotor and affective components. Microinjections of naloxone (1 microgram) also reversed the blocking effect of DAME and the thresholds returned to the control level within 10 min while microinjection of normal saline as control had no effect. The excitatory effects of naloxone and inhibitory effects of DAME were statistically significant at P < 0.01 and P < 0.05 respectively with Wilcoxon's signed rank test. The present study indicates that enkephalinergic as well as opioidergic mechanisms operating at the midbrain (VTA) level are involved in the inhibition of predatory attack as elicited from lateral hypothalamus.

Effect of aspartate and glutamate on nociception, catalepsy and core temperature in rats.

Effects of excitatory aminoacids (EAAs) aspartate (ASP) and glutamate (GLU) in a low (50 ng, i.c.) and high dose (20 micrograms, i.c.), were studied on nociception, catalepsy and rectal temperature in albino rats. Both ASP and GLU altered the tail flick reaction time to thermal stimulation in a dose dependent manner, increasing it with low doses and reduced with high doses. Naloxone (10 micrograms, ic) antagonized the anti-nociceptive effect of EAAs while ketamine (10 micrograms, ic)-a NMDA receptor antagonist antagonized the hyperalgesic effect. These EAAs also antagonized catalepsy induced by haloperidol, chlorpromazine, trifluoperazine and morphine. Both ASP and GLU produced a hyperthermic response in all animals, including those in which hypothermia was induced by reserpine. These EAAs produced a comparable central modulatory effects on nociception, catalepsy and core temperature.

Peptidergic mechanisms in feeding behaviour.

Hyperphagia was induced in mice by p.o. administration of different types of CNS depressant drugs, like chlordiazepoxide 25 mg/kg diazepam 2.5 mg/kg, cyproheptadine 2 mg/kg and phenobarbitone 25 mg/kg. Such hyperphagia was abolished by pretreatment with naloxone 0.1 mg/kg sc. Naloxone per se at this dose produced no significant effect on the food intake. This is suggestive of the role of peptidergic mechanisms in the feeding behaviour in mice.

Evaluación de un algoritmo para el manejo de niños con shock séptico / Evaluation of a septic shock treatment algorythim in children

Para poner a prueba un algoritmo diseñado para facilitar el tratamiento del shock séptico, se estudiaron en el Servicio de Terapia Intensiva Pediátrica del Hospital General Centro Médico La Raza, 35 niños con edad promedio de 12.7 meses que tenían datos (clínicos y de laboratorio) de shock séptico hipodinámico. La primera fase del algoritmo consistió en la administración de metilprednisolona (30 mg/kg), naloxona (100 ug/kg/dosis) y coloides, habiendo observado una sobrevivencia del 61 por ciento y una letalidad secundaria al shock de 19 por ciento. En la segunda fase se aplicó dopamina (5 ug/kg/min) y dobutamina (5 a 20 ug/kg/min), con sobrevivencia de 38 por ciento; no presentaron nuevo shock el 23 por ciento del total y la letalidad fue de 30 por ciento. La tercera fase consistió en la transfusión de paquete globular, menor de 72 horas, observando 100 por ciento de sobrevivencia; ningún niño presentó nuevo shock. En dos niños se hizo exanguinotransfusión en la cuarta fase del algoritmo; ambos murieron. Se concluye que el algoritmo de manejo del shock séptico es útil, los esteroides son eficases cuando se aplican tempranamente. Las medidas que se tomen para nutrir a los niños deben ponerse en práctica tempranamente, para así reducir el efecto del hipercatabolismo y evitar la evolución hacia la falla orgánica múltiple

El papel del sistema opiáceo endógeno en el síndrome depresivo y en el afecto de sujetos normales / The function of the endogenous opioid system in the depressive syndrome and in the affect of normal subjec

En este artículo se revisan los diferentes abordajes que se han hecho, para el estudio del sistema endógeno opiáceo (SEO), en el síndrome depresivo y en la modulación del afecto en sujetos normales, desde un punto de vista clínico. Desde el año de 1975, cuando se identificaron los primeros péptidos opioides por Hughes y Kosterlitz, se postularon diferentes hipóteis respecto a la participación del SEO en los trastornos afectivos. Se han utilizado al menos tres estrategias para dicho fin: 1) estudios postmortem de cerebros y de líquido cerebro espinal, tanto en pacientes deprimidos como en sujetos normales, 2) estudios con agonistas del receptor opiáceo (i.g. morfina), 3) estudios con antagonistas del receptor opiáceo (i.g. naxolona). Aunque la evidencia no ha demostrado una alteración del SEO si juega un papel importante en la modulación del afecto y las respuestas neuroendócrinas, tanto en el síndrome depresivo como en los sujetos normales. Existen aún puntos por esclarecer en cuanto a la fisiopatología del trastorno afectivo

Efecto protector de naloxona y piroxicam durante la lesión por isquemia-reperfusión de intestino delgado / Protector effect of naloxone and piroxicam during ischemia-reperfusion injury

El presente trabajo consistió en un modelo experimental con ratas en el cual valoramos el efecto protector de piroxicam, cimetidina y naloxona durante la lesión por isquemia-reperfusión de intestino delgado. Las dosis de naloxona fueron mayores a las que empleamos en trabajos previos. En los animales tratados con piroxicam y naloxona se encontró un efecto protector que mejoró el índice de supervivencia en estos animales, lo cual correlaciona con la ausencia de necrosis y de infiltrado leucocitario en el estudio histopatológico. Sin embargo, las dosis mayores de naloxona empleadas en este trabajo no mejoraron el efecto protector. La cimetidina no mostró ningún efecto protector. Se analizan los posibles mecanismos de acción de estos fármacos durante la lesión por isquemia-reperfusión

Antídotos de uso reciente

Los antídotos son sustancias cuya función es contrarrestar el efecto farmacológico y tóxico de otras sustancias, teniendo en cuenta la importancia de las medidas generales en el manejo del intoxicado (baño general, emesis, lavado gástrico, carbón activado, catárticos). Cada día aparecen sustancias nuevas con dichas características. En el presente artículo se pretende dar información breve y detallada sobre las propiedades farmacológicas, indicaciones, dosificación, efectos secundarios y contraindicaciones de algunos de uso general (carbón activado, soluciones electrolíticas con polietilenglycol) y principalmente de algunos específicos de uso reciente: flumazenil, fragmentos Fab-antidigoxina, glucagón, naloxona, clonidina, N-acetil-cisteína, azul de metileno, nitrito y tiosulfato de sodio, ácido-2-3-dimercaptosuccínico, penicilina benzatínica, glicopirrolato y S-adenosil-metionina.

Manejo anestésico de endarterectomía de carótida: caso clínico / Anesthetic management of carotid endarterectomy: case report

En el presente estudio se describe el manejo anestésico de la endarterectomía de la arteria carótida interna en un paciente sometido dos veces a esta intervención quirúrgica. Se efectuó registro electroencefalográfico contínuo durante el procedimiento anestésico-quirúrgico: inducción con diazepam, tiopental y fentanil; relajación muscular con pancuronio para facilitar la intubación endotraqueal; mantenimiento con dos dosis subsecuentes de 600 *g de fentanil; ventilación mecánica controlada con oxígeno al 100 por ciento, volumen corriente 10 ml/kg y frecuencia para mantener la EFECO2 entre 30 y 32 torrs. La administración de naloxona, 60 *g iv, inmediatamente antes del pinzamiento de la arteria carótida interna modificó los signos electroencefalográficos del efecto del fentanil, provocando desincronización y actividad rápida de bajo voltaje en el electroencefalograma, situación que facilitó la identificación de los signos electroencefalográficos de izquemia asociados al pinzamiento de la arteria carótida interna, sin modificar el estado anestésico de la paciente. Se discute la importancia del registro electroencefalográfico contínuo que permite la identificación inmediata de signos electroencefalográficos de isquemia cerebral, así como las medidas de protección contra el daño cerebral en estas condiciones.

Participation of nucleous raphe obscurus in the control of sympathetic activity in the anesthetized rat

The medullary raphe are involved in the control of sympathetic activity during desynchonized sleep and in the modulation of nocicepotive sensory inpts. To determine the particpation cholinergic and opiate mechanisms in the control of sympathetic activity, we microinjected eserine, morphine and naloxone into the nucleus raphe obscurus (NRO) of urethane-anesthetized rats. Arterial blood pressure (BP) and renal nerve activity (RN) were recorded. Eserine and morphine induced significant reductions of RN and BP, while naloxone had no effect. It is suggested that cholinergic and opiate mechanisms particpate in the control of sympathetic activity by th NRO