Functional respiratory imaging after neostigmine- or sugammadex-enhanced recovery from neuromuscular blockade in the anesthetised rat: a randomised controlled pilot study / Imagem funcional da respiração após aceleração da recuperação do bloqueio neuromuscular com neostigmina ou sugamadex em ratos anestesiados: estudo piloto controlado e randomizado

Abstract Objectives Reductions in diaphragm activity are associated with the postoperative development of atelectasis. Neostigmine reversal is also associated with increased atelectasis. We assessed the effects of neostigmine, sugammadex, and spontaneous reversal on regional lung ventilation and airway flow. Methods Six Sprague-Dawley rats were paralysed with rocuronium and mechanically ventilated until recovery of the train-of-four ratio to 0.5. We administered neostigmine (0.06 mg.kg-1), sugammadex (15 mg.kg-1), or saline (n = 2 per group). Computed tomography scans were obtained during the breathing cycle. Three-dimensional models of lung lobes were generated using functional respiratory imaging technology, and lobar volumes were calculated during the breathing cycle. The diaphragmatic surface was segmented for the end-expiratory and end-inspiratory scans. The total change in volume was reported by the lung volume change from the end-expiratory scan to the end-inspiratory scan. Chest wall movement was defined as the lung volume change minus the volume change that resulted from diaphragm excursion. Results The two rats that received neostigmine exhibited a smaller relative contribution of diaphragm movement to the total change in lung volume compared with the two rats that received sugammadex or saline (chest wall contribution (%): 26.69 and 25.55 for neostigmine; -2.77 and 15.98 for sugammadex; 18.82 and 10.30 for saline). Conclusion This pilot study in rats demonstrated an increased relative contribution of chest wall expansion after neostigmine compared with sugammadex or saline. This smaller relative contribution of diaphragm movement may be explained by a neostigmine-induced decrease in phrenic nerve activity or by remaining occupied acetylcholine receptors after neostigmine.

Resumo Objetivos As reduções da atividade do diafragma estão associadas ao desenvolvimento de atelectasia no período pós-operatório. A reversão com neostigmina também está associada ao aumento de atelectasia. Avaliamos os efeitos de neostigmina, sugamadex e da reversão espontânea sobre a ventilação pulmonar regional e o fluxo aéreo. Métodos Seis ratos Sprague-Dawley foram paralisados com rocurônio e mecanicamente ventilados até a recuperação da sequência de quatro estímulos atingir relação 0,5. Administramos neostigmina (0,06 mg.kg-1), sugamadex (15 mg.kg-1) ou solução salina (n = 2 por grupo). As tomografias foram feitas durante o ciclo respiratório. Modelos tridimensionais dos lobos pulmonares foram gerados com a tecnologia de imagem funcional respiratória e os volumes lobares foram calculados durante o ciclo respiratório. A superfície diafragmática foi segmentada para as varreduras expiratória final e inspiratória final. A alteração total no volume foi relatada pela alteração do volume pulmonar da varredura expiratória final para a varredura inspiratória final. O movimento da parede torácica foi definido como a variação do volume pulmonar menos a alteração no volume resultante da excursão do diafragma. Resultados Os dois ratos que receberam neostigmina apresentaram uma contribuição relativa menor do movimento do diafragma para a alteração total do volume pulmonar em comparação com os dois ratos que receberam sugamadex ou solução salina (contribuição da parede torácica (%): 26,69 e 25,55 para neostigmina; -2,77 e 15,98 para sugamadex; 18,82 e 10,30 para solução salina). Conclusão Este estudo piloto com ratos demonstrou uma contribuição relativa aumentada de expansão da parede torácica após neostigmina em comparação com sugamadex ou solução salina. Essa contribuição relativa menor de movimento do diafragma pode ser explicada por uma redução induzida por neostigmina na atividade do nervo frênico ou por receptores de acetilcolina permanecerem ocupados após a administração de neostigmina.

The effect of sugammadex on postoperative cognitive function and recovery / O efeito de sugamadex sobre a função cognitiva e recuperação no pós-operatório

Abstract Background and objective: Sugammadex is the first selective relaxant binding agent. When compared with neostigmine, following sugammadex administration patients wake earlier and have shorter recovery times. In this study, we hypothesized that fast and clear awakening in patients undergoing general anesthesia has positive effects on cognitive functions in the early period after operation. Methods: Approved by the local ethical committee, 128 patients were enrolled in this randomized, prospective, controlled, double-blind study. Patients were allocated to either Sugammadex group (Group S) or the Neostigmine group (Group N). The primary outcome of the study was early postoperative cognitive recovery as measured by the Montreal Cognitive Assessment (MoCA) and Mini Mental State Examination (MMSE). After baseline assessment 12-24 h before the operation. After the operation, when the Modified Aldrete Recovery Score was ≥9 the MMSE and 1 h later the MoCA tests were repeated. Results: Although there was a reduction in MoCA and MMSE scores in both Group S and Group N between preoperative and postoperative scores, there was no statistically significant difference in the slopes (p > 0.05). The time to reach TOF 0.9 was 2.19 min in Group S and 6.47 min in Group N (p < 0.0001). Recovery time was 8.26 min in Group S and 16.93 min in Group N (p < 0.0001). Conclusion: We showed that the surgical procedure and/or accompanying anesthetic procedure may cause a temporary or permanent regression in cognitive function in the early postoperative period. However, better cognitive performance could not be proved in the Sugammadex compared to the Neostigmine.

Resumo Justificativa e objetivo: Sugamadex é o primeiro agente de ligação relaxante seletivo. Após a administração de sugamadex, os tempos de despertar e de recuperação dos pacientes são menores, em comparação com neostigmina. Neste estudo, a hipótese foi que um despertar mais rápido e claro dos pacientes submetidos à anestesia geral tem efeitos positivos sobre as funções cognitivas no pós-operatório imediato. Métodos: Após a aprovação do Comitê de Ética local, 128 pacientes foram incluídos neste estudo prospectivo, randômico, controlado e duplo-cego. Os pacientes foram designados para o grupo sugamadex (Grupo S) ou grupo neostigmina (Grupo N). O desfecho primário do estudo foi a recuperação cognitiva no pós-operatório imediato, de acordo com a mensuração da Avaliação de Montreal da Função Cognitiva (MoCA) e com o Mini Exame do Estado Mental (MMSE), após a avaliação inicial 12-24 h antes da operação. Após a operação, quando o escore de recuperação de Aldrete modificado era ≥ 9, o teste MMSE e, uma hora depois, o teste MoCA foram repetidos. Resultados: Embora tenha havido uma redução nos escores de MoCA e MMSE tanto no Grupo S quanto no Grupo N, entre os escores pré- e pós-operatório não houve diferença estatisticamente significativa nas reduções (p > 0,05). O tempo para atingir TOF 0,9 foi de 2,19 min no Grupo S e de 6,47 min no Grupo N (p < 0,0001). O tempo de recuperação foi de 8,26 min no Grupo S e de 16,93 min no Grupo N (p < 0,0001) Conclusão: Mostramos que o procedimento cirúrgico e/ou procedimento anestésico de acompanhamento pode causar uma regressão temporária ou permanente da função cognitiva no pós-operatório imediato. No entanto, um desempenho cognitivo melhor não pode ser provado no grupo sugamadex em comparação com o grupo neostigmina.

Sugammadex versus neostigmine in pediatric patients: a prospective randomized study / Sugammadex versus neostigmina em pacientes pediátricos: estudo prospectivo e randomizado / Sugammadex versus neostigmina en pacientes pediátricos: estudio prospectivo y aleatorizado

Background and objectives: Acetylcholinesterase inhibitors may cause postoperative residual curarization when they are used for reversal of neuromuscular blockade. Sugammadex reverses neuromuscular blockade by chemical encapsulation and is not associated with the side effects that may occur with the use of anticholinesterase agents. Because of increased outpatient surgical procedures postoperative residual curarization and rapid postoperative recovery have a greater importance in the pediatric patient population. The aim of this study was to compare the efficacy of sugammadex and neostigmine on reversing neuromuscular blockade in pediatric patients undergoing outpatient surgical procedures. Methods: 80 patients, aged 2-12 years, scheduled for outpatient surgery were enrolled in this randomized prospective study. Neuromuscular blockade was achieved with 0.6 mgkg−1 rocuronium and monitorized with train-of-four. Group RN (n = 40) received 0.03 mgkg−1 neostigmine, Group RS (n = 40) received 2 mgkg−1 sugammadex for reversal of rocuronium. Extubation time (time from the reversal of neuromuscular blockade to extubation), train-of-four ratio during this time, time to reach train-of-four > 0.9, and probable complications were recorded. Results: There was no significant difference between the patients' characteristics. Extubation time and time to reach train-of-four > 0.9 were significantly higher in Group RN (p = 0.001, p = 0.002). Train-of-four at the time of neostigmine/sugammadex injection in Group RN were significantly higher than in the RS group (p = 0.020). Extubation train-of-four ratio was significantly lower in Group RN (p = 0.002). Conclusion: Sugammadex provides safer extubation with a shorter recovery time than neostigmine in pediatric patients undergoing outpatient surgical procedures. .

Justificativa e objetivos: Os inibidores da acetilcolinesterase podem causar curarização residual no pós-operatório quando usados para reverter o bloqueio neuromuscular. Sugamadex reverte o bloqueio neuromuscular por encapsulação química e não está associado aos efeitos colaterais que podem ocorrer com o uso de agentes anticolinesterase. Devido ao aumento dos procedimentos cirúrgicos ambulatoriais. A curarização residual e a rápida recuperação no pós-operatório são muito importantes para a população de pacientes pediátricos. O objetivo deste estudo foi comparar a eficácia de sugamadex e neostigmina na reversão do bloqueio neuromuscular em pacientes pediátricos submetidos a procedimentos cirúrgicos ambulatoriais. Métodos: 80 pacientes, com idades entre 2-12 anos, programados para cirurgias ambulatoriais foram incluídos neste estudo prospectivo e randomizado. O bloqueio neuromuscular foi obtido com 0,6 mgkg−1 de rocurônio e monitorizado com a interpretação da sequência de quatro estímulos. O Grupo RN (n = 40) recebeu 0,03 mgkg−1 de neostigmina e o Grupo RS (n = 40) recebeu 2 mgkg−1 de sugamadex para a reversão de rocurônio. O tempo de extubacão (tempo desde a reversão do bloqueio neuromuscular até a extubação), a razão da sequência de quatro estímulos durante esse tempo, o tempo para atingir uma sequência de quatro estímulos > 0,9 e as complicações prováveis foram registrados. Resultados: Não houve diferença significativa entre as características dos pacientes. Os tempos de extubação e para atingir uma sequência de quatro estímulos >0,9 foram significativamente maiores no Grupo RN (p = 0,001, p = 0,002). A sequência de quatro estímulos ...

Introducción y objetivos: Los inhibidores de la acetilcolinesterasa pueden causar anestesia residual en el postoperatorio cuando se usan para revertir el bloqueo neuromuscular. El sugammadex revierte el bloqueo neuromuscular por encapsulación química y no está asociado con los efectos colaterales que pueden ocurrir con el uso de agentes anticolinesterasa. Debido al aumento de los procedimientos quirúrgicos ambulatorios, la anestesia residual y la rápida recuperación en el postoperatorio son muy importantes para la población de pacientes pediátricos. El objetivo de este estudio fue comparar la eficacia del sugammadex y la neostigmina en la reversión del bloqueo neuromuscular en pacientes pediátricos sometidos a procedimientos quirúrgicos ambulatorios. Métodos: 80 pacientes, con edades entre 2 y 12 años, programados para cirugía ambulatoria fueron incluidos en este estudio prospectivo y aleatorizado. El bloqueo neuromuscular se obtuvo con 0,6 mg kg−1 de rocuronio y fue monitorizado con la interpretación de la secuencia de 4 estímulos. El grupo RN (n = 40) recibió 0,03 mg kg−1 de neostigmina y el grupo RS (n = 40) recibió 2 mg kg−1 de sugammadex para la reversión de rocuronio. Se registraron el tiempo de desintubación (tiempo desde la reversión del bloqueo neuromuscular hasta la desintubación), la razón de la secuencia de 4 estímulos durante ese tiempo, el tiempo para alcanzar una secuencia de 4 estímulos > 0,9 y las complicaciones probables. Resultados: No hubo diferencia significativa entre las características de los pacientes. Los tiempos de desintubación y para alcanzar una secuencia de 4 estímulos > 0,9 fueron significativamente mayores en el grupo RN (p = 0,001, p = 0,002). La secuencia de 4 estímulos en el momento de la inyección de neostigmina/sugammadex ...

Comparison of effects of sugammadex and neostigmine on QTc prolongation in rabbits under general anesthesia

PURPOSE: To compare the effects of sugammadex and neostigmine, used to antagonize the effects of rocuronium, on the QTc interval. METHODS: This study used 10 adult New Zealand white rabbits of 2.5-3.5 kg randomly divided into two groups: sugammadex group (Group S, n:5) and neostigmine group (Group N, n:5). For general anesthesia administering 2 mg/kg iv propofol and 1 mcg/kg iv fentanyl, 0.6 mg/kg iv rocuronium was given. Later to provide reliable airway for all experimental animals V-Gel Rabbit was inserted. The rabbits were manually ventilated by the same anesthetist. After the V-Gel Rabbit was inserted at 2, 5, 10, 20, 25, 27, 30 and 40 minutes measurements were repeated and recorded. At 25 minutes after induction Group N rabbits were given 0.05 mg/kg iv neostigmine + 0.01 mg/kg iv atropine. Group S were administered 2 mg/kg iv sugammadex. RESULTS: Comparing the QTc interval in the rabbits in Group S and Group N, in the 25th, 27th and 30th minute after muscle relaxant antagonist was administered the QTc interval in the neostigmine group rabbits was significantly increased (p<0.05). CONCLUSION: While sugammadex, administered to antagonize the effect of rocuronium, did not significantly affect the QTc interval, neostigmine+atropine proloned the QTc interval. .

Some current challenges in research on air pollution and health / Desafíos actuales de la investigación sobre contaminación del aire y salud

This commentary addresses some of the diverse questions of current interest with regard to the health effects of air pollution, including exposure-response relationships, toxicity of inhaled particles and risks to health, multipollutant mixtures, traffic-related pollution, accountability research, and issues with susceptibility and vulnerability. It considers the challenges posed to researchers as they attempt to provide useful evidence for policy-makers relevant to these issues. This commentary accompanies papers giving the results from the ESCALA project, a multi-city study in Latin America that has an overall goal of providing policy-relevant results. While progress has been made in improving air quality, driven by epidemiological evidence that air pollution is adversely affecting public health, the research questions have become more subtle and challenging as levels of air pollution dropped. More research is still needed, but also novel methods and approaches to address these new questions.

Este comentario aborda algunos de los temas de interés actual en relación con los efectos de la contaminación del aire sobre la salud, tales como las relaciones exposición-respuesta, la toxicidad y riesgos para la salud de las partículas inhaladas, las mezclas de contaminantes múltiples, la contaminación relacionada con el tráfico, la investigación sobre responsabilidad, y los problemas de susceptibilidad y vulnerabilidad. Considera los retos que se presentan a los investigadores que intentan proporcionar evidencia para los responsables políticos en estas cuestiones. Este texto acompaña otros trabajos con resultados del proyecto ESCALA, un estudio en varias ciudades de América Latina que tiene como objetivo general proporcionar resultados relevantes para la política pública. Aunque ha habido avances para mejorar la calidad del aire, gracias a la evidencia epidemiológica de que la contaminación aérea está afectando negativamente a la salud pública, las preguntas de investigación se han vuelto más sutiles y difíciles a medida que los niveles de contaminación se reducen. Se necesita más investigación, pero también nuevos métodos y enfoques capaces de enfrentar estas preguntas.

Effect of Itopride Hydrochloride on the Ileal and Colonic Motility in Guinea Pig In Vitro

PURPOSE: Itopride hydrochloride (itopride) inhibits acetylcholinesterase (AChE) and antagonizes dopamine D(2) receptor, and has been used as a gastroprokinetic agent. However, its prokinetic effect on the small bowel or colon has not yet been thoroughly investigated. The aim of this study was to investigate the effects of itopride on motor functions of the ileum and colon in guinea pigs. MATERIALS AND METHODS: The distal ileum was excised and the activity of peristaltic contraction was determined by measuring the amplitude and propagation velocity of peristaltic contraction. The distal colon was removed and connected to the chamber containing Krebs-Henseleit solution (K-H solution). Artificial fecal matter was inserted into the oral side of the lumen, and moved toward the anal side by intraluminal perfusion via peristaltic pump. Colonic transit times were measured by the time required for the artificial feces to move a total length of 10cm with 2-cm intervals. RESULTS: In the ileum, itopride accelerated peristaltic velocity at higher dosage (10(-10)-10(-6)M) whereas neostigmine accelerated it only with a lower dosage (10(-10)-10(-9)M). Dopamine (10(-8)M) decelerated the velocity that was recovered by itopride infusion. Itopride and neostigmine significantly shortened colonic transit at a higher dosage (10(-10)-10(-6)M). Dopamine (10(-8)M) delayed colonic transit time that was also recovered after infusion of itopride. CONCLUSION: Itopride has prokinetic effects on both the ileum and colon, which are regulated through inhibitory effects on AChE and antagonistic effects on dopamine D(2) receptor.

Neostigmine for the Treatment of Acute Hepatic Encephalopathy with Acute Intestinal Pseudo-obstruction in a Cirrhotic Patient

We treated a 49-yr-old man with neostigmine, who had liver cirrhosis, acute hepatic encephalopathy, and acute intestinal pseudoobstruction. He was admitted in a state of hepatic confusion. On physical examination, the abdomen was distended; and bowel sound was absent. Plain abdomen film revealed multiple airfluid levels and distention of bowel loops. Initially, we gave him lactulose enemas every 6 hr for one day without improvement in his mental state. Furthermore, he became to a state of coma. Therefore, we gave him 0.5 mg of neostigmine subcutaneously to improve his peristaltic movement, and 2 L of polyethylene glycol electrolyte solution through a nasogastric tube for 4 hr to reduce the production and absorption of gutderived toxins of nitrogenous compounds. After these treatments, the venous ammonia level decreased to the normal range within 12 hr, and the coma disappeared after 2 days. We suggest that neostigmine may be one of the most effective treatments to initiate peristaltic movement and bowel cleansing in cirrhotic patients with acute hepatic encephalopathy and acute intestinal pseudoobstruction.

Tactile TOF count as a predictive factor for the efficacy of neostigmine reversal of rocuronium-Induced blockade during propofol or sevoflurane anesthesia

This study was done to determine whether train-of-four [TOF] count is a good predictor to the efficacy of neostigmine administration for reversal of rocuronium-induced blockade during propofol or sevoflurane anaesthesia, and to follow subsequent recovery until the TOF reached 0.9. One-hundred-twenty patients, divided into eight equal groups, were randomly allocated to maintenance of anaesthesia with propofol or sevoflurane. The tactile response of the adductor pollicis to TOF stimulation was evaluated on one arm, and the mecha-nomyographic response was recorded on the other Neuromuscular block was induced with rocuronium 0.6 mg.kg[-1] and maintained with rocuronium to 15% of the control first twitch in TOF, neostigmine 0.07mg.Kg[-1] was administered on reappearance of the first [Group I], second [Group II], third [Group III], or fourth [Group IV] tactile TOF-response in each anaesthesia. The times from administration of neostigmine until the ratio recovered to 0.7, 0.8 and 0.9 were recorded. The times [[median [range]] to TOF ratio - 0.9 were 8.2 [4.5-17.3], 7.8 [3.6-11.9], 5.6 [1.8-9.1], and 4.4 [1.1-7.6] min in Groups I-IV during propofol anaesthesia, respectively, and 24.6 [8.1-66.3], 22.8 [7.6-51.1], 15.4 [7.1-39.7], and 9.1 [4.9-22.3] minutes in corresponding groups during sevoflurane anaesthesia, respectively, [p<0.05]. We recommend more than 2 TOF responses with propofol anaesthesia and 4 TOF responses with sevoflurane anaesthesia for adequate reversal within 10 and 15 minutes, respectively. The more tactile TOF responses present at the time of reversal achieved greater adequate recovery

Cholinergic-NO-cGMP mediation of sildenafil-induced antinociception.

Acetylcholine and cholinomimetic agents with predominant muscarinic action are known to increase the concentration of cGMP by activation of nitric oxide signaling pathway in the nociceptive conditions. The present study was aimed to investigate the NO-cGMP-PDE5 pathway in nociceptive conditions in the experimental animals. Nociceptive threshold was assessed by acetic acid-induced writhing assay (chemonociception) or carrageenan-induced hyperalgesia. Sildenafil [1-5 mg/kg, ip, 50-200 microg/paw, intraplantar (ipl)] produced dose dependent antinociception in both the tested models. Coadministration of acetylcholine (50 mcg/paw, ipl) or cholinomimetic agent, neostigmine (0.1 mcg/kg, ip and 25 ng/paw, ipl) augmented the peripheral antinociceptive effect of sildenafil. This effect was sensitive to blockade by L-NAME (20 mg/kg, ip, 100 microg/paw, ipl), a non-selective NOS inhibitor and methylene blue (1 mg/kg, ip), a guanylate cyclase inhibitor, which per se had little or no effect in both the models of nociception. Further, the per se analgesic effect of acetylcholine and neostigmine was blocked by both L-NAME and methylene blue in the models of nociception, suggesting the activation of NO-cGMP pathway. Also, both L-NAME and methylene blue blocked the per se analgesic effect of sildenafil. These results indicate the peripheral accumulation of cGMP may be responsible for antinociceptive effect, and a possible interaction between cholinergic agents and PDE5 system in models of nociception.

Rocuronium bromide: a pharmacological study

This work was designed to assess the pharmacological effects of rocuronium. In either isolated preparation or intact animals. Rocuronium [6-96 micro g/ml] caused a significant dose related reduction in the amplitude of rat phrenic nerve diaphragm contraction in response to indirect stimulation, the mean percentage reduction were statistically significant. The addition of neostgmine [0.25 micro g/ml] caused complete reversal of the relaxant effect of rocuronium . In intact cat gastrocnemius sciatic nerve preparation rocuronium [25 - 200 micro g/kg] caused dose dependent statiscally significant reduction. In comparing the drug with succinyl choline by the head drop method the mean time in second was 15.34 +/-1.57 and 10.44 +/-0.91 respectively

Neuromuscular blocking effects of an alkaloidal extract from Inula royleana: contractile and electrical studies on amphibian skeletal muscle in vitro.

The neuromuscular blocking properties of an alkaloidal extract from the root of Inula royleana have been investigated in vitro using a combination of mechanical and electrophysiological approaches. Neurogenic twitches of the frog sartorius were profoundly inhibited by concentrations of the extract > or = 20 micrograms/ml, being reduced to 50% of control amplitude in approximately 90 s at a concentration of > or = 20 micrograms/ml. They were partially reversed by neostigmine (6 micrograms/ml), and by prolonged washout of the extract. Muscle surface action potentials, recorded with extracellular electrodes, also declined rapidly in amplitude in the presence of the extract. Direct muscle stimulation during inhibition by the extract elicited contractions and action potentials whose magnitudes were similar to control responses. Resting membrane potentials, and the intracellular input impedance of the skeletal muscle cells, were not significantly changed by the alkaloids. These results indicate that the extract has significant neuromuscular blocking activity of a partially or slowly reversible nature. The block appears to be exerted at the postjunctional end-plate nicotine receptors, thus offering promise for the identification of novel cholinergic receptor antagonist(s).

Prokinetic effect of erythromycin on contractility of an isolated strip of rabbit's intestine compared with neostigmine and metoclopramide

Intestinal hypomotility is a major problem after surgery on gastrointestinal tract and in certain conditions. Prokinetic effect of erythromycin on ILEAL contractility on an isolated strip of rabbit's intestine was compared with that of neostigmine and metoclopramide. Effect of neostigmine is highly significant [P > 0.001] in increasing contractility in intestinal muscle strips Metoclopramide effectively increased contractility [P > 0.1] and erythromycin also significantly [P > 0.05] improved contractility. This study proved that erythromycin is a potent Prokinetic agent, which can be useful in conditions associated with gastrointestinal hypomotility

La estimulación colinérgica central en la desnervación sinoaórtica. Efecto de la administración i.c.v. de agentes colinomiméticos / The central cholinergic stimulation in the sinoaortic denervation. Effect of the intracerebroventricular administration of cholinomimetic agents

Se decidió encarar el estudio farmacológico de la participación colinérgica en el modelo de desnervación sinoaórtica analizando los efectos cardiovasculares de agonistas muscarínicos diversos y del anticolinesterásico neostigmina administrados por vía endovenosa o por la vía intracerebroventricular. También se evaluó la actividad de la enzima acetilcolinesterasa en diversas estructras del sistema nervioso central luego de la a inhibición por administración intracerebral de neostigmina pero disminuye el efecto bradicardizante. Sin embargo no alteraría las respuestas cardiovasculares correspondientes a la inyección i.v. del agonista oxotremorina y a la i.c.v. del agonista McNeil-A-343. Luego de la administración i.c.v. de neostigmina, la actividad enzimática remanente osciló entre 24 por ciento a 30 por ciento en las estructuras hipotalámicas y entre 42 por ciento a 52 por ciento en los restantes tejidos, sin diferencias entre las ratas con operación simulada y aquellas con desnervación sinoaórtica. Los resultados sugieren que en los efectos cardiovasculares de la estimulación colinérgica central posiblemente no estarían involucrados receptores muscarínicos del subtipo M1. Por otra parte, no estaría afectada la degradación de la acetilcolina en el sistema nervioso central, lo que apoyaría la idea de un compromiso de receptores muscarínicos en los cambios observados. Por la ruta de administración utilizada de neostigmina, se observa un mayor grado de inhibición de la acetilcolinesterasa hipotalámica, sugiriendo entonces que las estructuras hipotalámicas podrían estar comprometidas en los efectos cardiovasculares inducidos por la administración intracerebral del anticolinesterásico.

Antinociceptive effect of intrathecal neostigmine evaluated in rats by two different pain models

The analgessic efficacy of cholinergic agonists and anticholinesterase agents has been widely recognized. The analgesic effect obtained by activating cholinergic mechanisms, however, seems to depend on the experimental pain model utilized for its evaluation. The antinociceptive effect of intraspinal neostigmine was examined in rats submitted concurrently to the tail flick and formalin tests. Neostigmine (8.25 and 16.5 nmol) produced a dose-dependent antinociceptive effect in the tail flick test (a model of phasic pain) and reduced the first phase (phasic pain) of the animal response to formalin also in a dose-dependent manner. The second phase (tonic pain) of the response to formalin, however, was slightly reduced after a longer period of time only by the higher dose of the anticholinesterase. The effect of neostigmine was not significantly different when the drug was injected into rats submitted exclusively to the tail flick test. The second phase of the animal response to formalin was slightly reduced by neostigmine (8.25 nmol) and strongly inhibited by the higher dose of the anticholinesterase when injection was made after the first phase. We conclude that phasic and tonic pain can both be controlled by high doses of neostigmine. In addition, we show that inhibition by a lower dose of neostigmine of the formalin-induced phasic pain did not prevent the subsequent occurrence of tonic pain produced by the irritant.

Acción anticolinérgica de clonidina sobre los efectos cardiovasculares de la estimulación colinérgica central / Anticholinergic action of clonidine on cardiovascular effects of the central cholinergic estimulation

Fue realizado un estudio acerca de la acción anticolinérgica del agonista adrenérgico alfa2 clonidina sobre las respuestas cardiovasculares a la inyección i.c.v. del agente anticolinesterásico cuaternario neostigmina a ratas conscientes. E1 agente colinérgico neostigmina (0,1-1 mug i.c.v.) indujo en las ratas una respuesta presora y bradicardia en forma dependiente de la dosis. Clonidina, a la dosis de 10 mug. Kg(-1) (i.v.) y administrado 30 min antes del anticolinesterásico, no modificó el efecto presor de neostigmina (0,1-1 mug i.c.v.) pero previno la bradicardia. Por otra parte, la administración i.c.v. de clonidina (3 mug), inyctada 15 min. antes de neostigmina, sólo previno el efecto bradicardizante del anticolinesterásico (0,3 mug i.c.v.) pero la acción presora central de la droga. Estos resultados sostienen la idea de que la clonidina tiene una acción anticolinérgica en la rata. Sin embargo, la prevención por clonidina de la bradicardia inducida por estimulación central sugiere una interacción diferente colinérgica-adrenérgica según la respuesta cardiovascular originada por la administración central de agentes colinérgicos. .

Miastenia gravis: diagnóstico farmacológico pelo teste da neostigmina / Myasthenia gravis: avaliable pharmacological by tests of the neostigmine

Os autores fazem uma revisäo das manifestaçöes clínicas da Miastenia gravis. Discutem os vários testes farmacológicos e concluem que o da neostigmina é o mais prático, por seu amplo e seguro uso em hospitais gerais