No description available.

Thesis (doctoral)--Lund University, 1997. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1995. / Added t.p. with thesis statement inserted.

Thesis (doctoral)--Lund University, 1995. / Added t.p. with thesis statement inserted.

Le Gengyun. / Thesis submitted in: December 2002. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 161-182). / Abstracts in English and Chinese. / Abstract --- p.i / Abbreviations --- p.v / Acknowledgements --- p.vii / Publications --- p.viii / Table of Contents --- p.ix / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter 1. --- Vasoconstrictors --- p.1 / Chapter 1.1 --- An overview of vascular smooth muscle contraction --- p.1 / Chapter 1.2 --- Strong and weak vasoconstrictors --- p.5 / Chapter 1.2.1 --- Mechanisms involved in TP receptor vasoconstriction --- p.6 / Chapter 1.2.1.1 --- Brief introduction to the TP receptor --- p.6 / Chapter 1.2.1.2 --- Second messenger systems --- p.6 / Chapter 1.2.1.3 --- G-protein-linked pathways --- p.7 / Chapter 1.2.1.3.1 --- G proteins --- p.7 / Chapter 1.2.1.3.2 --- G-protein-linked TP receptor signal transduction --- p.8 / Chapter 1.2.2 --- Mechanisms involved in α1-adrenoceptor vasoconstriction --- p.8 / Chapter 1.2.2.1 --- Brief introduction to the α1-adrenoceptor --- p.8 / Chapter 1.2.2.2 --- Second messenger systems --- p.9 / Chapter 1.2.2.3 --- G-protein-linked α-adrenoceptor signal transduction --- p.9 / Chapter 1.3 --- Prostanoid EP3 receptor agonists (weak vasoconstrictors) --- p.10 / Chapter 1.3.1 --- Prostanoids --- p.10 / Chapter 1.3.1.1 --- Biochemical characteristics of prostanoids --- p.10 / Chapter 1.3.1.1.1 --- Biosynthesis of prostanoids --- p.10 / Chapter 1.3.1.1.2 --- Metabolism of prostanoids --- p.11 / Chapter 1.3.1.2 --- Prostanoid receptors --- p.13 / Chapter 1.3.1.2.1 --- Structures --- p.13 / Chapter 1.3.1.2.2 --- Current Status of Classification --- p.14 / Chapter 1.3.1.2.3 --- Signal transduction --- p.16 / Chapter 1.3.1.2.4 --- Distribution --- p.18 / Chapter 1.3.1.2.5 --- Physiological functions --- p.18 / Chapter 2. --- Interactions between vasoconstrictors --- p.19 / Chapter 2.1 --- Cross-talk between G-protein-coupled receptors --- p.19 / Chapter 2.1.1 --- Cross-talk between different receptor families --- p.19 / Chapter 2.1.2 --- Cross-talk between subtypes of the same receptor family --- p.21 / Chapter 2.1.3 --- Cross-talk at the effector level --- p.23 / Chapter 2.2 --- Proposed pathways involved in synergistic interactions --- p.24 / Chapter 2.2.1 --- Rho and Rho-associated kinase --- p.24 / Chapter 2.2.1.1 --- Rho family and its identification --- p.24 / Chapter 2.2.1.2 --- Mechanism(s) of Rho contribution in vasoconstriction --- p.25 / Chapter 2.2.1.3 --- Interactions between Rho and other pathways --- p.26 / Chapter 2.2.2 --- Receptor tyrosine kinases --- p.29 / Chapter 2.2.2.1 --- RTK family --- p.29 / Chapter 2.2.2.2 --- Activation of RTKs --- p.29 / Chapter 2.2.2.3 --- Mechanism(s) of RTK contribution in vasoconstriction --- p.30 / Chapter 2.2.2.4 --- Interactions between RTKs and MAPKs --- p.31 / Chapter 2.2.3 --- Mitogen-activated protein kinase --- p.34 / Chapter 2.2.3.1 --- p38 MAPK --- p.35 / Chapter 2.2.3.2 --- JNK MAPK --- p.35 / Chapter 2.2.3.3 --- ERK MAPK --- p.36 / Chapter 2.2.3.4 --- Interactions between MAPK and GPCRs --- p.37 / Chapter Chapter 2 --- FORCE MEASUREMENT SYSTEM --- p.41 / Chapter 1. --- Introduction --- p.41 / Chapter 2. --- Materials --- p.41 / Chapter 2.1 --- Drugs --- p.41 / Chapter 2.2 --- Chemicals --- p.41 / Chapter 2.3 --- Solutions --- p.46 / Chapter 3. --- Methods --- p.46 / Chapter 3.1 --- Isolated smooth muscle preparations and organ bath set-up --- p.46 / Chapter 3.2 --- Data analysis --- p.47 / Chapter Chapter 3 --- VASOCONSTRICTORS AND THEIR INTERACTIONS --- p.48 / Chapter 1. --- Introduction --- p.48 / Chapter 2. --- Materials and Methods --- p.48 / Chapter 2.1 --- Materials --- p.48 / Chapter 2.2 --- Methods --- p.51 / Chapter 2.2.1 --- Isolated tissue preparations --- p.51 / Chapter 2.2.2 --- Experimental protocols --- p.51 / Chapter 2.2.3 --- Statistical analysis --- p.52 / Chapter 3. --- Results --- p.55 / Chapter 3.1 --- Typical vasoconstrictor profiles of agonists --- p.55 / Chapter 3.1.1 --- Sulprostone contraction --- p.55 / Chapter 3.1.2 --- U-46619 contraction --- p.55 / Chapter 3.1.3 --- Phenylephrine contraction --- p.56 / Chapter 3.2 --- Synergistic interactions between sulprostone and strong vasoconstrictors --- p.58 / Chapter 3.2.1 --- Enhancement of U-46619 response by sulprostone --- p.58 / Chapter 3.2.2 --- Enhancement of phenylephrine response by sulprostone --- p.58 / Chapter 3.2.3 --- Enhancement of sulprostone response by phenylephrine --- p.58 / Chapter Chapter 4 --- INVESTIGATION OF PATHWAYS INVOLVED IN EP3 AGONIST- INDUCED VASOCONSTRICTION --- p.64 / Chapter 1. --- Introduction --- p.64 / Chapter 2. --- Materials and methods --- p.65 / Chapter 2.1 --- Materials --- p.65 / Chapter 2.2 --- Methods --- p.65 / Chapter 2.2.1 --- Isolated tissue preparations --- p.65 / Chapter 2.2.2 --- Experimental protocols --- p.65 / Chapter 2.2.3 --- Statistical analysis --- p.69 / Chapter 3. --- Results --- p.70 / Chapter 3.1 --- Effects of tyrosine kinase inhibitors --- p.70 / Chapter 3.2 --- Effects of MAPK inhibitors --- p.82 / Chapter 3.2.1 --- Effects of MAPK inhibitors on U-46619 responses --- p.82 / Chapter 3.2.2 --- Effects of MAPK inhibitors on sulprostone responses --- p.91 / Chapter 3.2.3 --- Effects of MAPK inhibitors on phenylephrine responses --- p.100 / Chapter 3.3 --- Effects of Rho-kinase inhibitors --- p.104 / Chapter Chapter 5 --- TRANSFECTED CELL LINE SYSTEM --- p.111 / Chapter 1. --- Introduction --- p.111 / Chapter 2. --- Materials and methods --- p.114 / Chapter 2.1 --- Materials --- p.114 / Chapter 2.1.1 --- Plasmids and vectors --- p.114 / Chapter 2.1.2 --- Radioactive agents --- p.114 / Chapter 2.1.3 --- Chemicals --- p.114 / Chapter 2.1.4 --- Restriction digest enzymes --- p.115 / Chapter 2.1.5 --- "Culture media, buffers and solutions" --- p.115 / Chapter 2.1.5.1 --- Culture media / Chapter 2.1.5.2 --- Buffers and solutions --- p.115 / Chapter 2.2 --- Methods --- p.116 / Chapter 2.2.1 --- Transfected cell lines --- p.116 / Chapter 2.2.1.1 --- Subcloning of hEP3-1 receptor and hTP receptor cDNA --- p.116 / Chapter 2.2.1.1.1 --- Plasmid recovery / Chapter 2.2.1.1.2 --- Preparation of competent cells --- p.116 / Chapter 2.2.1.1.3 --- Transformation of competent cells --- p.117 / Chapter 2.2.1.1.4 --- Extraction of DNA by QIAGEN Plasmid Mini Kit --- p.117 / Chapter 2.2.1.1.5 --- Restriction enzymes digestion and dephosphorylation --- p.117 / Chapter 2.2.1.1.6 --- DNA recovery and ligation / Chapter 2.2.1.1.7 --- Positive recombinant DNA selection --- p.119 / Chapter 2.2.1.2 --- Cell culture --- p.119 / Chapter 2.2.1.3 --- Transient transfection of CHO cells --- p.121 / Chapter 2.2.1.4 --- Mesurement of adenylate cyclase activity --- p.121 / Chapter 2.2.1.4.1 --- Preparation of columns --- p.121 / Chapter 2.2.1.4.2 --- [3H]-cAMP assays --- p.122 / Chapter 2.2.1.5 --- Measurement of phospholipase C activity --- p.122 / Chapter 2.2.1.5.1 --- Preparation of columns --- p.123 / Chapter 2.2.1.5.2 --- [3H]-inositol phosphate assay --- p.123 / Chapter 2.2.2 --- Data analysis --- p.124 / Chapter 3. --- Results --- p.125 / Chapter 3.1 --- Subcloning of hEP3-1and hTPα receptor cDNA into expression vectors --- p.125 / Chapter 3.2 --- Measurement of cAMP and IP production in transfected CHO cells --- p.133 / Chapter 3.2.1 --- Effect of varying receptor cDNA concentration on agonist-stimulated [3H]-cAMP and [3H]-IP production in transiently transfected CHO cells --- p.133 / Chapter 3.2.2 --- Effect of agonists on intracellular [3H]-IP or [3H]-cAMP productionin CHO cells transfected with hTPα or hEP3-1 --- p.133 / Chapter 3.3 --- Summary --- p.134 / Chapter Chapter 6 --- GENERAL DISCUSSION AND CONCLUSIONS --- p.137 / Chapter 1. --- Vasoconstrictors and their interactions --- p.137 / Chapter 1.1 --- Vasoconstrictors --- p.137 / Chapter 1.2 --- Synergism --- p.138 / Chapter 2. --- Investigation of possible pathways --- p.140 / Chapter 2.1 --- Rho-associated kinase --- p.140 / Chapter 2.2 --- Receptor tyrosine kinase --- p.147 / Chapter 2.3 --- Mitogen-activated protein kinase (MAPK) --- p.151 / Chapter 3. --- Effect of vehicles --- p.155 / Chapter 4. --- Biochemical studies in transfected CHO cells --- p.157 / Chapter 5. --- Conclusions --- p.158 / Appendix I --- p.159 / Buffers and Solutions used in transfected system --- p.159 / Chapter 1. --- Buffers --- p.159 / Chapter 2. --- Solutions --- p.159 / REFERENCES --- p.161

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 4 uppsatser.

Hung Hoi Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 138-160). / Abstracts in English and Chinese. / ABSTRACT --- p.i / ACKNOWLEDGEMENTS --- p.v / PUBLICATIONS BASED ON THE WORK IN THIS THESIS --- p.vi / TABLE OF CONTENTS --- p.vii / ABBREVIATIONS --- p.ix / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Prostanoids and vasoconstriction --- p.1 / Chapter 1.1.1 --- EP3 receptors --- p.2 / Chapter 1.1.2 --- EP1 receptors --- p.16 / Chapter 1.1.3 --- FP receptors --- p.23 / Chapter 1.1.4 --- TP receptors --- p.30 / Chapter 1.2 --- Role of Ca2+ in vascular smooth muscle contraction --- p.36 / Chapter 1.2.1 --- Ca2+ as second messenger --- p.36 / Chapter 1.2.2 --- Ca2+ sensitization --- p.41 / Chapter 1.3 --- Aim of study --- p.48 / Chapter CHAPTER 2 --- METHODS AND MATERIALS --- p.49 / Chapter 2.1 --- Experiments with rat femoral artery --- p.49 / Chapter 2.2 --- Experiments with guinea-pig trachea --- p.56 / Chapter 2.3 --- Materials --- p.59 / Chapter 2.4 --- Data analysis --- p.61 / Chapter 2.5 --- Measurement of rat knee joint blood flow --- p.62 / Chapter CHAPTER 3 --- RESULTS --- p.68 / Chapter 3.1 --- Effects of EP3 agonists and other vasoactive agents on the rat femoral artery preparation --- p.68 / Chapter 3.2 --- Interactions between EP3 agonists and other vasoactive agents --- p.69 / Chapter 3.2.1 --- Interactions with phenylephrine --- p.69 / Chapter 3.2.2 --- Interactions with KCl --- p.71 / Chapter 3.3 --- Effect of nifedipine --- p.72 / Chapter 3.4 --- Effects of Rho-kinase inhibitors --- p.73 / Chapter 3.5 --- Effect of EP1 receptor antagonist --- p.76 / Chapter 3.6 --- Other properties of the rat femoral artery --- p.77 / Chapter 3.8 --- Effect of sulprostone on blood flow of rat knee joint --- p.79 / Chapter CHAPTER 4 --- DISCUSSION --- p.118 / Chapter 4.1 --- Effect of PGE analogues on rat femoral artery --- p.118 / Chapter 4.1.1 --- Prostanoid receptor (s) responsible for the contractile effects --- p.118 / Chapter 4.1.2 --- Prostanoid Receptors involved in the synergism --- p.122 / Chapter 4.1.3 --- Synergism models --- p.124 / Chapter 4.2 --- Mechanisms of synergistic contractions --- p.126 / Chapter 4.2.1 --- Role of Ca2+ influx --- p.126 / Chapter 4.2.2 --- Role of Ca2+ sensitization --- p.127 / Chapter 4.3 --- Effect of sulprostone in vivo --- p.132 / Chapter 4.4 --- Conclusion --- p.136 / REFERENCES --- p.138

Vasoconstriction can be initiated via the interaction of a number of chemicals with specific "receptive sites" known as the receptors. This thesis examines two distinctly different modes by which drugs initiate a contractile response, namely, (i) the interaction of angiotensin analogues with a heterogeneous population of angiotensin receptors in vascular smooth muscles, and (ii) the conditions whereby B-adrenoceptor antagonists interact with a-adrenoceptor antagonists thereby causing a pressor response. Conscious, unrestrained, instrumented-rats were used for the study. It has been suggested that angiotensin receptors in vascular and non-vascular tissues may not be of a homogeneous population. The first study examined whether a heterogeneous population of angiotensin receptors was responsible for increasing vascular tone. Dose-response curves were constructed for angiotensin II (ANG II) and des Asp¹ angiotensin II (ANG III) on mean arterial pressure (MAP) and mean circulatory filling pressure (MCFP), an index of total body venous tone, in the presence or absence of [Sar¹, Ile⁸]ANG II. The i.v. infusion of ANG II or ANG III caused dose-dependent increases in MAP and MCFP. In the presence of [Sar¹, Ile⁸]ANG II, the MAP and MCFP curves for ANG II were displaced to the right with pA₂ values of 9.2 and 8.4 for the arterioles and veins, respectively. However, the antagonist displaced dose-MCFP but not the dose-MAP response curve of ANG III. This suggests that ANG II and ANG III act on the same receptor in veins but not arterioles. This concept was further investigated by obtaining dose-MAP and dose-MCFP response curves for ANG II in the presence of ANG II or ANG III. Dose-MAP response curve to ANG II was displaced to the right in the presence of ANG II but not ANG III. Dose-MCFP response curve for ANG II was displaced to the right in the presence of ANG III but not ANG II. These results again suggest that ANG III acts on the same receptors as ANG II in the veins but not arterioles. In the last series of experiments two analogues of angiotensin III were compared as antagonists of the pressor response to ANG II and ANG III. In the presence of [Ile⁷]ANG III, the dose-MAP response curves for ANG II and ANG III were displaced to the right while in the presence of [Sar¹, Ile⁷]ANG III, the dose-MAP response curve for ANG III but not ANG II was displaced. This suggests that [Sar¹, Ile⁷]ANG III is a selective antagonist of ANG III in the arterioles. In summary, the results indicate that ANG III acts on a different sub-class of angiotensin receptors than ANG II in the arterioles but it may act as a partial agonist on the same type of receptors as ANG II in the venous bed. Thus, ANG II receptors in the arterioles appear to be different from those in veins. The administration of a non-selective β-antagonist propranolol into animals subjected to non-selective α-blockade has been observed to cause a paradoxical pressor response. This second study examines whether the paradoxical pressor response to β-antagonists was due to: (i) an interaction of a β-antagonist with an α-antagonist, (ii) blockade of vasodilator β₂-adrenoceptors or (iii) an increase in the release of catecholamines. Cumulative dose-response curves for propranolol, atenolol (β₁-antagonist) and ICI 118,551 (β₂-antagonist) were obtained in rats subjected to a continuous i.v. infusion of phentolamine, a non-selective α-antagonist. The administration of each of the β-antagonists caused a dose-dependent increase in MAP suggesting that the pressor response was not due to the blockade of vasodilator β₂-adrenoceptors. Another four groups of phentolamine-treated rats were given a single i.v. bolus injection of saline, propranolol, atenolol or ICI 118,551, and sampling of arterial blood for the determination of adrenaline (A) and noradrenaline (NA) concentration by HPLC/ec. Phentolamine caused a decrease in MAP and an increase in the plasma levels of A and NA. Subsequent injection of propranolol, atenolol and ICI 118,551 but not saline increased MAP. Neither saline nor any of the β-antagonists increased plasma NA or A levels suggesting that the pressor response was not associated with an acute increase in the release of catecholamines. It was also shown that prior injection of a β-antagonist partially antagonized the hypotensive effect of phentolamine suggesting that the pressor response was related to an interaction between α- and β-antagonists. It was further shown that a continuous infusion of either prazosin or rauwolseine caused a small but not significant decrease in MAP which was reversed by propranolol. Concurrent infusions of prazosin and rauwolscine caused a large decrease in MAP. Subsequent injection of propranolol caused a large pressor response. On the contrary, sodium nitroprusside or metha-choline each decreased MAP but the hypotension was not antagonized by propranolol. These results were consistent with the existence of a specific interaction between α- and β-antagonists. These experiments demonstrated that although the mechanisms involved in the initiation of a change in vascular tone did not share a common pathway, the final outcome shared a common denomination. / Medicine, Faculty of / Anesthesiology, Pharmacology and Therapeutics, Department of / Graduate

Introdução: O prognóstico da parada cardiorrespiratória (PCR) em ritmo não chocável (assistolia/atividade elétrica sem pulso) é ruim e não melhorou significativamente nas últimas décadas. Embora a epinefrina seja o vasopressor recomendado, há evidências de que ela eleva o consumo de oxigênio, reduz a pressão de perfusão subendocárdica, causa grave disfunção miocárdica e piora a microcirculação cerebral durante a ressuscitação cardiopulmonar. Vasopressina foi muito estudada nos últimos anos e não se mostrou superior à epinefrina. Naloxona e terlipressina têm sido cogitadas como potenciais vasopressores no tratamento da PCR, entretanto há poucos estudos publicados e os resultados são controversos e inconclusivos. Objetivos: Avaliar os efeitos hemodinâmicos e metabólicos da terlipressina ou naloxona na PCR induzida por hipóxia e compará-las com o tratamento-padrão (epinefrina ou vasopressina). Métodos: Estudo experimental, randomizado, cego e controlado. Ratos Wistar adultos, machos, foram anestesiados, submetidos a traqueostomia e ventilados mecanicamente. A PCR foi induzida por obstrução da traqueia e mantida por 3,5 minutos. Em seguida, os animais foram ressuscitados de forma padronizada e randomizados em um dos grupos: placebo (n = 7), vasopressina (n = 7), epinefrina (n = 7), naloxona (n = 7) ou terlipressina (n = 21). Variáveis hemodinâmicas foram monitorizadas durante todo o experimento (via cateter intra-arterial e intraventricular) e mensuradas na base, no 10o (T10), 20o (T20), 30o (T30), 45o (T45) e 60o (T60) minutos pós-PCR. Amostras de sangue arterial foram coletadas para gasometria, hemoglobina, bioquímica e lactato em quatro momentos [base, 11o (T11), 31o (T31), e 59o (T59) minutos pós-PCR]. Resultados: Os grupos foram homogêneos e não houve diferença significativa entre eles nas variáveis de base. O retorno da circulação espontânea ocorreu em 57% dos animais no grupo placebo (4 de 7) e 100% nos demais grupos (p = 0,002). A ! sobrevida em 1 hora foi de 57% no grupo placebo, 71,4% no grupo epinefrina, 90,5% no grupo terlipressina e de 100% nos demais grupos. Comparado com o grupo epinefrina, o grupo terlipressina teve maiores valores de PAM no T10 (164 vs 111 mmHg; p = 0,02), T20 (157 vs 97 mmHg; p < 0,0001), T30 (140 vs 67 mmHg; p < 0,0001), T45 (117 vs 67 mmHg; p = 0,002) e T60 (98 vs 62 mmHg; p = 0,026). O lactato arterial no grupo naloxona foi significativamente menor quando comparado ao grupo epinefrina, no T11 (5,15 vs 8,82 mmol/L), T31 (2,57 vs 5,24 mmol/L) e T59 (2,1 vs 4,1 mmol/L)[p = 0,002]. Ao longo da 1a hora pós-PCR, o grupo naloxona apresentou o melhor perfil do excesso de bases (-7,78 mmol/L) quando comparado ao grupo epinefrina (-12,78 mmol/L; p = 0,014) e ao grupo terlipressina (-11,31 mmol/L; p = 0,024). Conclusões: Neste modelo de PCR induzida por hipóxia em ratos, terlipressina e naloxona foram eficazes como vasopressores na RCP e apresentaram melhor perfil metabólico que a epinefrina. A terlipressina resultou em uma maior estabilidade hemodinâmica na 1a hora pós-PCR comparada com a epinefrina ou a vasopressina. Os efeitos metabólicos favoráveis da naloxona não são explicados pelos valores da PAM / Introduction: The prognosis of cardiac arrest (CA) with nonshockable rhythm (asystole/pulseless electrical activity) is poor and not improved significantly in recent decades. Epinephrine is the most commonly used vasopressor, although there is evidence that its use correlates with myocardial dysfunction and worsens the cerebral microcirculation. Vasopressin has been widely studied in recent years and was not superior to epinephrine. Naloxone and terlipressin have been considered as potential vasopressors in the treatment of CA, however, there are few published studies and the results are controversial and inconclusive. Objectives: To evaluate the hemodynamic and metabolic effects of terlipressin or naloxone in CA induced by hypoxia and compare with standard treatment with epinephrine or vasopressin. Methods: Experimental, randomized, blinded and controlled trial. Adult male Wistar rats were anesthetized, the proximal trachea was surgically exposed, and a 14-gauge cannula was inserted 10 mm into the trachea to the larynx. They were mechanically ventilated and monitored. The CA was induced by tracheal obstruction and maintained for 3.5 minutes. Subsequently, the animals were resuscitated using standard maneuvers and randomized to one of groups: placebo (n=7), vasopressin (n=7), epinephrine (n=7), naloxone (n=7) or terlipressin (n=21). Hemodynamic variables were monitored throughout the study (intra-arterial and intra-ventricular catheter) and measured at baseline, in the 10th (T10), 20th (T20), 30th (T30), 45th (T45) and 60th (T60) minute post-cardiac arrest. Arterial blood samples were collected for hemoglobin, biochemistry, blood gases and lactate at four moments: baseline, 11th (T11), 31st (T31) and 59th (T59) minute post-cardiac arrest. Results: The groups were homogenous and there were no significant differences among them regarding the baseline variables. The return of spontaneous circulation (ROSC) occurred in 57% of the animals (4 of 7) in the placebo group and in 100% in the ! other groups (P=0.002). One-hour survival was 57% in the placebo group, 71.4% in the epinephrine group, 90.5% in the terlipressin and 100% in the naloxone group. Compared with the epinephrine group, the terlipressin groups had a significantly higher MAP at the T10 (164 x 111 mmHg; P=0.02), T20 (157 x 97 mmHg; P<0.0001), T30 (140 x 67 mmHg; P=0.0001), T45 (117 x 67 mmHg; P=0.002) and T60 (98 x 62 mmHg; P= 0.026). The blood lactate in naloxone group was significantly lower when compared to epinephrine group in the T11 (5.15 x 8.82 mmol/L), T31 (2.57 x 5.24 mmol/L) and T59 (2.1 x 4.1)[P=0.002]. Along the first hour after cardiac arrest, the naloxone group showed the best profile of base excess (- 7.78 mmol/L) when compared to epinephrine (-12.78 mmol/L, P= 0.014) and terlipressin group (-11.31 mmol/L, P=0.024). Conclusions: In this model of CA induced by hypoxia in rats, terlipressin and naloxone were effective as vasopressors in resuscitation and had better metabolic profile compared to epinephrine. Terlipressin resulted in higher hemodynamic stability in the first hour after CA and significantly better than epinephrine or vasopressin. The favorable metabolic effects of naloxone are not explained by the values of MAP

Introdução: É provável que o tratamento precoce da sepse grave e do choque séptico possa melhorar o desfecho dos pacientes. Objetivo: O objetivo deste estudo foi avaliar como o atraso no início da ressuscitação da sepse influencia a gravidade da doença, a intensidade das medidas de ressuscitação necessárias para atingir estabilidade hemodinâmica, o desenvolvimento da disfunção orgânica e a função mitocondrial. Métodos: Estudo experimental, prospectivo, randomizado e controlado, realizado em um laboratório experimental de um hospital universitário. Trinta e dois porcos submetidos à anestesia geral e ventilados mecanicamente foram randomizados (8 animais por grupo) em um grupo controle sadio ou para um de três grupos em que induziu-se peritonite fecal (instilação peritoneal de 2,0 g/kg de fezes autólogas) e, após 6 (deltaT-6h), 12 (deltaT-12h) ou 24 (deltaT-24h) horas, iniciou-se um período de 48 horas de ressuscitação protocolada. Resultados: O retardo no início da ressuscitação da sepse foi associada a sinais progressivos de hipovolemia e ao aumento dos níveis plasmáticos de interleucina-6 e do fator de necrose tumoral alfa. O atraso no início do tratamento da sepse resultou em balanço hídrico progressivamente positivo (2,1 ± 0,5 mL/kg/h, 2,8 ± 0,7 mL/kg/h e 3,2 ± 1,5 mL/kg/h, respectivamente, para os grupos deltaT-6h, deltaT-12h, e deltaT-24h, p < 0,01), maior necessidade de administração de noradrenalina durante as 48 horas de ressuscitação (0,02 ± 0,04 mcg/kg/min, 0,06 ± 0,09 mcg/kg/min e 0,13 ± 0,15 mcg/kg/min, p=0,059), redução da capacidade máxima de respiração mitocondrial cerebral dependente do Complexo II (p=0,048) e tendência a aumento da mortalidade (p=0,08). Houve redução do trifosfato de adenosina (ATP) na musculatura esquelética em todos os grupos estudados (p < 0,01), com os valores mais baixos nos grupos deltaT-12h e deltaT-24h. Conclusões: O aumento do tempo entre o início da sepse e o início das manobras de ressuscitação resultou no aumento da gravidade da doença, na maior intensidade das manobras de ressuscitação e na disfunção mitocondrial cerebral associada à sepse. Nossos resultados suportam o conceito da existência de uma janela crítica de oportunidade para ressuscitação da sepse / Introduction: Early treatment in sepsis may improve outcome. Objective: The aim of this study was to evaluate the impact of delays in resuscitation on disease severity, need for resuscitation, and the development of sepsis-associated organ and mitochondrial dysfunction. Methods: Prospective, randomized, controlled experimental study performed at an experimental laboratory in a university hospital. Thirty-two anesthetized and mechanically ventilated pig were randomly assigned (n = 8 per group) to a nonseptic control group or one of three groups in which fecal peritonitis (peritoneal instillation of 2 g/kg autologous feces) was induced, and a 48 hour period of protocolized resuscitation started 6 (deltaT-6 hrs), 12 (deltaT-12 hrs), or 24 (deltaT-24 hrs) hours later. Results: Any delay in starting resuscitation was associated with progressive signs of hypovolemia and increased plasma levels of interleukin-6 and tumor necrosis factor-alfa prior to resuscitation. Delaying resuscitation increased cumulative net fluid balances (2.1 ± 0.5 mL/kg/hr, 2.8 ± 0.7 mL/kg/ hr, and 3.2 ± 1.5 mL/kg/hr, respectively, for groups deltaT-6 h rs, delta T-12 hrs, and ?T-24 hrs; p < 0.01) and norepinephrine requirements during the 48-hr resuscitation protocol (0.02 ± 0.04 mcg/kg/min, 0.06 ± 0.09 mcg /kg/min, and 0.13 ± 0.15 mcg/kg/min; p=0.059), decreased maximal brain mitochondrial Complex II respiration (p=0.048), and tended to increase mortality (p=0.08). Muscle tissue adenosine triphosphate decreased in all groups (p < 0.01), with lowest values at the end in groups deltaT-12 hrs and deltaT-24 hrs. Conclusions: Increasing the delay between sepsis initiation and resuscitation increases disease severity, need for resuscitation, and sepsis-associated brain mitochondrial dysfunction. Our results support the concept of a critical window of opportunity in sepsis resuscitation