Every day, general anaesthetics are given to a large number of patients around the world but the cellular mechanisms of how anaesthetics act are still not clear. General anaesthetics cause the intended unconsciousness, amnesia and immobility in patients, but also side effects such as a decrease in mean arterial pressure and arrhythmia, both of which contribute to complications such as heart damage and stroke. With more knowledge of the mechanism of anaesthetic drugs, these complications could be reduced. It has been shown that anaesthetics cause a disruption of the thalamocortical connectivity and brain network connectivity. How the network communication is disrupted however is not known. Propofol and thiopental are both intravenous anaesthetic drugs used widely in clinical anaesthesia. They bind to the GABAA receptor and enhance its function. The cytoskeleton helps the cell to maintain its shape and participate in cellular movement and transport. Cellular transport to and from a neuron’s cell body and periphery is performed by motor proteins that move vesicles, organelles and proteins along cytoskeletal tracks. We have previously shown that propofol causes a reorganisation of the cytoskeleton protein actin in neurons, but we were further interested to study the effects of propofol and thiopental on the cytoskeletal function of cultured cortical rat neurons. Our results show that propofol and thiopental cause neurite (axon and dendrite) retraction. Propofol’s effects were time- and dose-dependent, and can be reversed when propofol is removed. We were able to inhibit propofolinduced neurite retraction if we stabilised actin by blocking either the motor protein myosin II or the GABAA receptor. We have previously shown that a small GTP-binding protein, RhoA, inhibits propofol-caused actin reorganisation. Propofol-induced neurite retraction was mediated via a downstream effector of RhoA, ROK, which induces phosphorylation of the myosin light chain and increases contractility. Furthermore, we have shown that propofol causes a switch from anterograde to retrograde transport and increases the average velocity of the moving vesicles in neurites. The propofol induced retrograde vesicle transport was GABAA receptor-mediated. Orexin A is a neuropeptide which regulates the sleep/awake cycle and has also been shown to reduce anaesthesia in animals when given intracerebroventricularly. We found that orexin A reverses propofol and thiopental-induced neurite retraction and actin reorganisation. Moreover, we have shown that the orexin A inhibition of propofol-induced neurite retraction is mediated via the PLD/PKC intracellular signalling pathway. Propofol and thiopental decreased the tyrosine phosphorilation of the intermediate cytoskeletal protein vimentin which is reversed by orexin A. Taken together, these results suggest that propofol causes a time- and dose-dependent, reversible and GABAAreceptor-mediated neurite retraction in cultured cortical rat neurons. Propofol also causes a switch from anterograde to retrograde vesicle transport in neurites. Orexin A reverses propofol and thiopental-induced neurite retraction and cytoskeletal reorganisation. Orexin A inhibits propofol-induced neurite retraction via the PLD/PKC intracellular signalling pathway.

Erlangen, Nürnberg, Universiẗat, Diss., 2007. / Enth. 1 Sonderabdr. aus: Anesthesia & analgesia ; Vol. 104. 2007. - Beitr. teilw. dt., teilw. engl.

Orientador: Newton Nunes / Coorientador: Patrícia Cristina Ferro Lopes / Banca: Paulo Sérgio Patto dos Santos / Banca: Roberta Carareto / Resumo: Avaliaram-se, comparativamente, os efeitos do tiopental e do propofol sobre os parâmetros cardiovasculares, respiratórios, hemogasométricos, nível glicêmico, cinética celular e período de recuperação. Para tanto, utilizaram-se 20 coelhos da raça Nova Zelândia Branco, adultos, machos ou fêmeas, com peso médio de 3,67±0,43 Kg. Após seleção aleatória, estes foram distribuídos em dois grupos de 10 animais, denominados grupo propofol (GP) e grupo tiopental (GT). Para o GP, foi induzida a anestesia geral pela administração intravenosa (IV) de propofol (10 mg/Kg) e em seguida, iniciou-se a infusão contínua na dose inicial 1 mg/Kg/min, a qual, havendo necessidade, foi reajustada de modo a que o índice biespectral estivesse situado entre 65 e 75. Para o GT empregou-se a mesma metodologia, substituindo-se o propofol pelo tiopental. As observações das variáveis de interesse em ambos os grupos, tiveram início 20 minutos após a indução anestésica (M0) e novas mensurações foram realizadas em intervalos de 15 minutos, por um período de 60 minutos. A avaliação da recuperação teve início 30 minutos (MR30) após o término da infusão dos fármacos e novas avaliações foram realizadas em intervalos de 60 minutos. Os dados foram submetidos à análise de variância de duas vias (Two-way ANOVA) e uma via (One-way ANOVA), seguidas pelo teste de Bonferroni (p<0,05). Para a análise da recuperação, os escores foram analisados e os grupos comparados pelo teste não paramétrico de Wilcoxon de 2 amostras independentes (p<0,05). No GP, a pressão parcial de oxigênio (PaO2) o dióxido de carbono (PaCO2) e a saturação da oxihemoglobina (SaO2) no sangue arterial aumentaram a partir do M30 e no M60, respectivamente. O volume corrente (VT), no M60, e o índice respiratório (IR), no M0, foram menores no GP, enquanto o conteúdo arterial de oxigênio (CaO2), no M0, foi maior no GP que no GT. A pressão de oxigênio alveolar ... / Abstract: The effects of thiopental and propofol were comparatively evaluated about its influence on cardiovascular and respiratory parameters, blood gas, blood glucose levels, cell kinetics and recovery period in 20 rabbits of New Zealand White, adults, male and female, with weight between 3,67±0,43 Kg. After a random selection, they were shared into two groups of 10 animals, called propofol group (GP) and thiopental group (GT). For GP, general anesthesia was induced by intravenous (IV) administration of propofol (10 mg/Kg) and then began continuous infusion at an initial dose 1 mg/Kg/min, and then was adjusted as necessary to the bispectral index values vary between 65 and 75. The same method was employed for GT, using thiopental instead propofol, at the dose of 10 mg/Kg for induction followed the initial dose of 1 mg/Kg/min. Data collection of the variables of interest in both groups began 20 minutes after induction of anesthesia (M0) and new measurements were made at 15 minutes intervals for a period of 60 minutes. The assessment of recovery began 30 minutes (MR30) after the infusion of agents and new evaluations were made at intervals of 60 minutes. Data were analysed using to analysis of variance, two-way (two-way ANOVA) and route (One-way ANOVA) followed by Bonferroni test (p<0,05). For recovery assessment, the scores were analyzed and the groups were compared by non parametric Wilcoxon test for 2 independent samples (p<0,05). In GP, the partial pressure of oxygen (PaO2), carbon dioxide (PaCO2) and oxyhemoglobin saturation (SaO2) in arterial blood increased from M30 and M60, respectively. The tidal volume (VT) in M60, and respiratory index (IR) in M0, were lower in the GP, while the arterial oxygen content (CaO2) at M0 was greater in GP than in GT. The alveolar oxygen tension (PAO2), alveolar-arterial oxygen difference (P(A-a)O2), IR, arterial-alveolar ratio (PaO2/PAO2) and ratio of partial pressure of arterial oxygen to fraction of ... / Mestre

by Wong Kwok Kong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 163-184). / Abstract --- p.2 / Preface / Acknowledgements --- p.6 / List of abbreviations --- p.7 / List of Tables --- p.8 / List of Figures --- p.13 / CONTENTS --- p.16 / Chapter Chapter One： --- Introduction --- p.23 / Chapter Chapter Two： --- Review of pharmacology of propofol --- p.26 / Chapter 1： --- Chemistry structure-Activity relationship --- p.27 / Chapter 2: --- Pharmacokinetics --- p.28 / Chapter 2.1： --- Distribution --- p.29 / Chapter 2.2： --- Elimination --- p.30 / Chapter 2.3: --- "Effects of age, sex, and hepatic and renal disease on the pharmacokinetics of propofol" --- p.35 / Chapter 2.3.1： --- Effects of age / Chapter 2.3.2： --- Effects of sex / Chapter 2.3.3: --- Effects of renal and hepatic disease / Chapter 3: --- Pharmacodynamic --- p.38 / Chapter 3.1： --- Anaesthetic concentrations --- p.38 / Chapter 3.2: --- Recovery characteristics --- p.39 / Chapter 3.3： --- Effects on the cardiovascular system --- p.40 / Chapter 3.4： --- Effects on the respiratory system --- p.43 / Chapter 3.5： --- Effects on cerebral blood flow and intracranial pressure --- p.44 / Chapter 3.6： --- Other effects --- p.45 / Chapter 3.6.1： --- Effects on liver function / Chapter 3.6.2： --- Effects on renal function / Chapter 3.6.3: --- Effects on coagulation / Chapter 3.6.4： --- Effects on adrenal steroidgenesis / Chapter 3.7： --- Side effects --- p.47 / Chapter 3.7.1： --- Pain on injection / Chapter 3.7.2: --- Excitatory & respiratory / Chapter 3.7.3: --- Nausea and vomiting / Chapter 3.7.4： --- Bradycardia / Chapter 3.7.5: --- Anaphylaxes / Chapter 4: --- Clinical use --- p.51 / Chapter 4.1： --- Anaesthesia induction --- p.52 / Chapter 4.2: --- Anaesthesia maintenance --- p.53 / Chapter 4.3: --- Use in sedation --- p.57 / Chapter Chapter Three ： --- Analytical Technique:Propofol content analysis --- p.58 / Chapter 1: --- Introduction high-pressure liquid chromatography --- p.58 / Chapter 2: --- Methods of propofol content analysis --- p.61 / Chapter 2.1: --- Reagents and solutions --- p.61 / Chapter 2.1.1: --- Sodium dihydrogen phosphate / Chapter 2.1.2： --- Cyclohexane / Chapter 2.1.3: --- Tetramethylammonium Hydroxide Solution / Chapter 2.1.4： --- Acetonitrile / Chapter 2.1.5: --- Acetic acid / Chapter 2.2: --- Standard solution --- p.62 / Chapter 2.2.1: --- Propofol standards / Chapter 2.2.2： --- Internal standard / Chapter 2.2.3： --- Control standard / Chapter 2.3： --- Mobile phase --- p.63 / Chapter 2.4： --- High-pressure liquid chromatography --- p.63 / Chapter 2.5: --- Quantification --- p.64 / Chapter 2.6： --- Procedure --- p.67 / Chapter 2.7： --- Throughput --- p.69 / Chapter 2.7.1： --- Fist working day / Chapter 2.7.2: --- Second working day / Chapter 2.7.3： --- Third working day / Chapter 2.7.4: --- Fourth working day / Chapter 2.7.5： --- Fifth working day / Chapter 3: --- Results of propofol content analysis --- p.71 / Chapter 3.1: --- Calibration standard of propofol (Linearity) --- p.71 / Chapter 3.2： --- Control standard of propofol --- p.74 / Chapter 3.2.1： --- Reproducibility / Chapter 3.2.2: --- Recovery / Chapter 3.2.3： --- Stability / Chapter 4: --- Discussion of propofol content analysis --- p.80 / Chapter 4.1： --- Calibration standard of propofol --- p.80 / Chapter 4.2: --- Precision and accuracy of analytical method --- p.86 / Chapter 4.3： --- Extraction efficiency of analytical method --- p.87 / Chapter 4.4： --- Stability of analytical met --- p.89 / Chapter Chapter Four： --- Analytical technique： Protein binding of propofol --- p.91 / Chapter 1: --- Introduction protein binding of propofol --- p.91 / Chapter 1.1: --- Ultrafiltration --- p.92 / Chapter 1.2： --- Equilibrium dialysis --- p.92 / Chapter 2: --- Methods of protein binding of propofol --- p.94 / Chapter 2.1： --- Material & Solution --- p.94 / Chapter 2.1.1: --- Dialysis buffer / Chapter 2.1.2: --- Molecularporous Dialysis Membrane / Chapter 2.2: --- Equilibrium dialysis --- p.96 / Chapter 2.3： --- Determine the optimum dialysis time to reach equilibrium --- p.97 / Chapter 2.3.1： --- Material / Chapter 2.3.2： --- Procedure / Chapter 3: --- Results of protein binding of propofol --- p.99 / Chapter 3.1： --- Results for optimum dialysis time to reach equilibrium --- p.99 / Chapter 3.2： --- Results for reproducibility --- p.101 / Chapter 3.2.1: --- Intraassay coefficient of variation (One analysis day) of propofol in plasma and in protein binding / Chapter 3.2.2: --- Interassay coefficient of variation (Seven analysis days) of propofol in plasma and in protein binding / Chapter 3.3: --- Results for recovery of propofol in plasma and in protein binding --- p.106 / Chapter 3.3.1: --- Recovery of propofol (unheated samples) / Chapter 3.3.2: --- Recovery of propofol (samples heated at 37°C) / Chapter 3.3.3: --- Recovery of propofol (after dialysis at 37°C) / Chapter 3.4： --- Results for stability of propofol in plasma --- p.112 / Chapter 4: --- Discussions of protein binding of propofol --- p.114 / Chapter 4.1: --- Optimum dialysis time to reach equilibrium --- p.114 / Chapter 4.2: --- Discussion for Intraassay & Interassay coefficient of variation of propofolin plasma and in protein binding --- p.114 / Chapter 4.3： --- Recovery of propofol in plasma and in protein binding --- p.116 / Chapter 4.4： --- Discussion for stability of propofolin plasma --- p.118 / Chapter Chapter Five： --- Clinical application of pharmacokinetic studies --- p.119 / Chapter 1: --- Introduction pharmacokinetic model controlled infusion / Chapter 1.1： --- Theoretical basis --- p.119 / Chapter 1.2: --- Use of computer & appropriate pump --- p.123 / Chapter 2: --- Results of propofol pharmacokinetic studies --- p.124 / Chapter 2.1: --- Sample prepare --- p.124 / Chapter 2.2: --- Computer control infusion of propofol according to pharmacokinetic model --- p.126 / Chapter 2.3: --- Comparison of measured and predicted blood concentrations of propofol --- p.129 / Chapter 2.4: --- Test the new paediatric pharmacokinetic model (the revised paediatric rate constants) --- p.136 / Chapter 3: --- Discussion of propofol pharmacokinetics studies： Infusion for Chinese children --- p.141 / Chapter Chapter Six： --- Clinical application on protein binding studies --- p.143 / Chapter 1: --- Plasma proteins and drug binding --- p.143 / Chapter 2: --- Methods of propofol protein binding studies --- p.145 / Chapter 2.1： --- Blood sample acquisition --- p.145 / Chapter 2.2: --- Population characteristics --- p.145 / Chapter 2.3： --- Methods of protein binding assay --- p.145 / Chapter 3: --- Results of propofol protein binding --- p.146 / Chapter 4: --- Discussion of propofol protein binding --- p.153 / Chapter 4.1: --- Protein binding of propofol in Chinese children --- p.154 / Chapter 4.2： --- Protein binding of propofol in pregnant women & neonate --- p.155 / Chapter Chapter Seven： --- Conclusions --- p.158 / References --- p.163 / Appendix --- p.180

Lim Thiam Aun. / Thesis (M.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 142-154). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Thèse d'exercice : Médecine. Anesthésie, réanimation chirurgicale : Université de Nantes : 2005. / Bibliogr. f. 70-75 [71 réf.].

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-02-17T18:21:05Z No. of bitstreams: 1 2015 - Renato Le?o S? de Oliveira.pdf: 1042208 bytes, checksum: 36444539adfac13a4589cce19eb24182 (MD5) / Made available in DSpace on 2017-02-17T18:21:05Z (GMT). No. of bitstreams: 1 2015 - Renato Le?o S? de Oliveira.pdf: 1042208 bytes, checksum: 36444539adfac13a4589cce19eb24182 (MD5) Previous issue date: 2015-08-20 / This study was developed in the Veterinary Hospital from UFRRJ. Forty cats, from the neutering program of our institution, were enrolled in this study. Cats were classified as ASA I or II to be accepted. The aim of this study was to verify the influence of the induction rate on the propofol requirement. We also aimed to quantify the propofol sparing effect of methadone and the incidence of side effects in these situations. Animals were randomly assigned to one of two premedication groups, receiving acepromazine (0,05 mg.kg-1) associated with saline (0,03 mL.kg-1) or methadone (0,3 mg.kg-1). Sedation scores were assessed 15 and 30 minutes after premedication using two scales (SDS and VAS). After the sedation assessment, animals were divided randomly in two more groups: fast (5 mg.kg-1.min-) or slow (1,5 mg.kg-1.min-1) induction rate. Sedation scores did not differed between groups neither over time. Just a slight sedation could be observed in both groups. Cats that received induction slowly had significantly more excitement as side effect of propofol. We could not observe difference between methadone and saline on the incidence of side effects. In fast induction rate we could not observe incidence of any side effects. Cats premedicated with methadone that received fast induction rate needed 33% less propofol than those that received saline and fast induction rate. When compared with both groups in slow induction rate, the propofol sparing effect of methadone was 38% when compared with fast induction rate. There were no differences between treatments in slow induction rate. Our results show the benefit of using methadone associated with acepromazine when an adequate induction rate is used. In addition we demonstrate that overly slow induction rates can increase the incidence of side effects as well as increase the amount of anesthetics used do achieve induction. / O presente trabalho foi desenvolvido no setor de pequenos animais do Hospital Veterin?rio da UFRRJ. Foram utilizados 40 gatos provenientes do programa de controle de natalidade de c?es e gatos da institui??o. Os animais se enquadraram como ASA I ou II para serem inclu?dos no estudo. Seu objetivo foi mensurar o potencial da metadona em reduzir o requerimento de propofol para indu??o anest?sica em gatos. Al?m disso objetivou avaliar a incid?ncia de efeitos adversos durante esta indu??o e comparar o efeito de diferentes velocidades de administra??o do anest?sico sobre estas vari?veis. Os animais foram distribu?dos em dois grupos para administra??o da medica??o pr?-anest?sica, um grupo recebeu acepromazina (0,05 mg.kg-1) associada a metadona (0,3 mg.kg-1) e outro grupo recebeu a acepromazina associada a solu??o salina est?ril (0,03 mL.kg-1). Os animais tiveram seus escores de seda??o avaliados nos tempos 15 e 30 minutos ap?s a administra??o dos protocolos, atrav?s de duas escalas: uma escala descritiva simples e uma escala anal?gica visual. Posteriormente a avalia??o dos escores de seda??o os animais foram novamente divididos em dois grupos: com indu??o com propofol na velocidade de 5 mg.kg-1.min-1 ou na velocidade de 1,5 mg.kg-1.min-1. Os escores de seda??o n?o variaram significativamente entre os grupos nem ao longo do tempo em ambas as escalas, sendo poss?vel observar apenas uma leve tranquiliza??o nos animais em ambos os grupos. Os animais que receberam metadona apresentaram sinais de euforia. Os animais que receberam a indu??o na velocidade mais lenta apresentaram maior incid?ncia de efeitos adversos al?m de apresentarem maior requerimento anest?sico para indu??o, sem diferen?a entre os grupos pr?-tratados ou n?o com metadona. Nos grupos com indu??o mais r?pida n?o foram evidenciados efeitos colaterais. A indu??o com a velocidade mais r?pida se apresentou mais segura por ser quase isenta de efeitos adversos. Os animais pr?-tratados com metadona e induzidos com velocidade maior, apresentaram significativa redu??o no requerimento de propofol, sendo esta redu??o de 33% frente aos animais n?o tratados com metadona e induzidos na mesma velocidade e de 38% frente aos animais induzidos com velocidade mais lenta, sem diferen?a entre os tratamentos. Estes resultados demonstram o benef?cio da utiliza??o de analg?sicos opi?ides na medica??o pr?-anest?sica, al?m do efeito analg?sico, mas tamb?m reduzindo o requerimento de agentes indutores e consequentemente seus efeitos delet?rios. Da mesma maneira demonstrou-se que indu??es em velocidades excessivamente lentas se apresentam como formas delet?rias de utiliza??o do propofol como agente indutor, aumentando seu requerimento e a incid?ncia de efeitos adversos.

O propofol é o fármaco mais freqüentemente empregado na indução da anestesia de pequenos animais apesar de seu efeito depressor cardiovascular e respiratório. Sabe-se que a associação com outros fármacos pode determinar a redução de suas doses e essa possibilidade é pouco conhecida nos felinos. No presente estudo, foram avaliados os efeitos do emprego do midazolam associado ao propofol na indução da anestesia em gatas submetidas a ovariossalpingo-histerectomia. Foram utilizadas 30 gatas, jovens adultas, submetidas a ovariossalpingo-histerectomia. Após serem pré-tratadas com acepromazina e morfina, foram distribuídas em três grupos: o grupo GP recebeu indução somente com propofol; o grupo GMP recebeu midazolam imediatamente antes da indução com propofol; e o grupo GPM recebeu uma subdose de propofol, seguido por midazolam e novamente propofol até ser possível a intubação. Foi avaliada a redução da dose do propofol quando em associação com midazolam; a qualidade de intubação endotraqueal e grau de relaxamento muscular; a qualidade de indução da anestesia após a administração de propofol ou propofol em associação com midazolam, analisando qual a melhor seqüência de administração e a qualidade e o tempo de recuperação nas gatas submetidas à indução da anestesia com propofol ou propofol-midazolam. Foram também observados as freqüências cardíaca e respiratória, pressão arterial, oximetria, capnometria e hemogasometria. A partir dos resultados obtidos verificou-se que a dose de propofol para indução da anestesia em gatas é reduzida em 34% e 23% quando precedido ou antecedido pelo midazolam, respectivamente; a associação com midazolam não intensificou o relaxamento muscular promovido pelo propofol, não interferindo assim na qualidade de intubação endotraqueal das gatas; o uso prévio de midazolam em relação ao propofol na indução da anestesia não determinou agitação, tampouco excitação nas gatas; ambas as seqüências de administração da associação propofol-midazolam são factíveis, porém a seqüência propofol-midazolam se mostrou superior devido a menor dose empregada de propofol; do ponto de vista clínico, a associação com midazolam determinou prolongamento do tempo de recuperação das gatas, mas não determinou efeitos adversos no momento de despertar. / Propofol is the most frequent drug used for induction of anesthesia in small animals. Its cardiovascular and respiratory depressor effects are well known. The association with other drugs may determine a reduction of its dose, and this possibility is not well known in cats. The present study evaluated the effects of midazolam associated to propofol during induction of anesthesia in cats submitted to ovariohysterectomy. Thirty cats were enrolled in this study. After premedicated with acepromazine and morphine, they were distributed in three groups: GP group that received only propofol for induction; GMP group that received midazolam immediately before propofol induction; and GPM group that received a sub dose of propofol, followed by midazolam and propofol until intubation was possible. The dose reduction of propofol when associated to midazolam; the quality of endotracheal intubation and the muscle relaxation degree were evaluated; the quality of anesthetic induction after administration of propofol or propofol associated with midazolam was compared, in order to identify the best administration sequence. The quality and time of recovery were evaluated as well. Heart and respiratory rates, arterial blood pressure, oximetry, capnometry and hemogasometry were also accessed. The results showed that propofol dose for anesthesia induction was reduced in 34% and 23% when preceded or succeeded by midazolam, respectively; The association with midazolam did not increase muscle relaxation promoted by propofol, therefore not interfering in the quality of endotracheal intubation in cats; the use of midazolam previously to propofol on anesthetic induction did not cause agitation or excitement; both sequence of administration of the association of propofol-midazolam were effective, although the sequence propofol-midazolam was been shown to be better, since the propofol dose was lower; from the clinic point of view, the association with midazolam determined a prolongation of the recovery, however no side effects were noted.

O propofol é o fármaco mais freqüentemente empregado na indução da anestesia de pequenos animais apesar de seu efeito depressor cardiovascular e respiratório. Sabe-se que a associação com outros fármacos pode determinar a redução de suas doses e essa possibilidade é pouco conhecida nos felinos. No presente estudo, foram avaliados os efeitos do emprego do midazolam associado ao propofol na indução da anestesia em gatas submetidas a ovariossalpingo-histerectomia. Foram utilizadas 30 gatas, jovens adultas, submetidas a ovariossalpingo-histerectomia. Após serem pré-tratadas com acepromazina e morfina, foram distribuídas em três grupos: o grupo GP recebeu indução somente com propofol; o grupo GMP recebeu midazolam imediatamente antes da indução com propofol; e o grupo GPM recebeu uma subdose de propofol, seguido por midazolam e novamente propofol até ser possível a intubação. Foi avaliada a redução da dose do propofol quando em associação com midazolam; a qualidade de intubação endotraqueal e grau de relaxamento muscular; a qualidade de indução da anestesia após a administração de propofol ou propofol em associação com midazolam, analisando qual a melhor seqüência de administração e a qualidade e o tempo de recuperação nas gatas submetidas à indução da anestesia com propofol ou propofol-midazolam. Foram também observados as freqüências cardíaca e respiratória, pressão arterial, oximetria, capnometria e hemogasometria. A partir dos resultados obtidos verificou-se que a dose de propofol para indução da anestesia em gatas é reduzida em 34% e 23% quando precedido ou antecedido pelo midazolam, respectivamente; a associação com midazolam não intensificou o relaxamento muscular promovido pelo propofol, não interferindo assim na qualidade de intubação endotraqueal das gatas; o uso prévio de midazolam em relação ao propofol na indução da anestesia não determinou agitação, tampouco excitação nas gatas; ambas as seqüências de administração da associação propofol-midazolam são factíveis, porém a seqüência propofol-midazolam se mostrou superior devido a menor dose empregada de propofol; do ponto de vista clínico, a associação com midazolam determinou prolongamento do tempo de recuperação das gatas, mas não determinou efeitos adversos no momento de despertar. / Propofol is the most frequent drug used for induction of anesthesia in small animals. Its cardiovascular and respiratory depressor effects are well known. The association with other drugs may determine a reduction of its dose, and this possibility is not well known in cats. The present study evaluated the effects of midazolam associated to propofol during induction of anesthesia in cats submitted to ovariohysterectomy. Thirty cats were enrolled in this study. After premedicated with acepromazine and morphine, they were distributed in three groups: GP group that received only propofol for induction; GMP group that received midazolam immediately before propofol induction; and GPM group that received a sub dose of propofol, followed by midazolam and propofol until intubation was possible. The dose reduction of propofol when associated to midazolam; the quality of endotracheal intubation and the muscle relaxation degree were evaluated; the quality of anesthetic induction after administration of propofol or propofol associated with midazolam was compared, in order to identify the best administration sequence. The quality and time of recovery were evaluated as well. Heart and respiratory rates, arterial blood pressure, oximetry, capnometry and hemogasometry were also accessed. The results showed that propofol dose for anesthesia induction was reduced in 34% and 23% when preceded or succeeded by midazolam, respectively; The association with midazolam did not increase muscle relaxation promoted by propofol, therefore not interfering in the quality of endotracheal intubation in cats; the use of midazolam previously to propofol on anesthetic induction did not cause agitation or excitement; both sequence of administration of the association of propofol-midazolam were effective, although the sequence propofol-midazolam was been shown to be better, since the propofol dose was lower; from the clinic point of view, the association with midazolam determined a prolongation of the recovery, however no side effects were noted.