Inibição da guanilato ciclase pelo azul de metileno no choque circulatório causado por pancreatite aguda necrosante: uma palavra de cuidado embasada em modelo suíno / Guanylate cyclase inhibition by methylene blue in circulatory shock caused by acute necrotizing pancreatitis: a word of caution based on a porcine model

OBJETIVO: estudar o uso terapêutico do bloqueio da guanilato ciclase pelo azul de metileno em um modelo experimental de pancreatite aguda grave em suínos. MÉTODOS: a pancreatite aguda necrotizante foi induzida em porcos anestesiados por infusão ductal pancreática retrógrada de 1ml/kg de taurocolato de sódio a 5% e 8U/kg de enteroquinase. Três grupos foram estudados (n=5): controle (C), pancreatite (PA), "bolus" de azul seguido por pancreatite (AM+PA). Os dados incluíram enzimas séricas e do líquido abdominal, variáveis hemodinâmicas, hemogasometria arterial, volume de líquido abdominal, marcadores inflamatórios plasmáticos, nitrito/nitrato e mieloperoxidase e malondialdeído plasmático. Aplicou-se a análise de variância seguida do pós-teste de Bonferroni (p<0,05). RESULTADOS: os valores de amilase e lipase foram três e dez vezes mais elevados no grupo PA. A atividade da mieloperoxidase foi 50% superior no grupo PA. Os dados hemodinâmicos indicaram choque hipovolêmico precoce seguido de choque cardiogênico. Observou-se grave translocação de líquidos para a cavidade peritoneal. A nitrito/nitrato plasmática permaneceu inalterada. O grupo AM+PA teve aumento de cinco vezes do mieloperoxidase em comparação com o grupo C. CONCLUSÕES: a utilização de azul de metileno em suínos com pancreatite não demonstrou efeitos significativos sobre variáveis hemodinâmicas e inflamatórias. Seu uso terapêutico na pancreatite necro-hemorrágica pode ser inadequado e extremo cuidado deve ser tomado dado o aumento da peroxidação lipídica evidenciado pelo aumento dos valores do malondialdeído.

OBJECTIVE: To study the therapeutic application of guanylate cyclase inhibition by methylene blue in an experimental model of acute pancreatitis in pigs. METHODS: acute necrotizing pancreatitis was induced in anesthetized pigs by the retrograde infusion of 1 ml/kg of 5% sodium taurocholate and 8 U/kg enterokinase in the pancreatic duct. Three groups were studied (n = 5): control (C), pancreatitis (AP), and MB bolus followed by pancreatitis (MB+P). The data included serum and abdominal fluid enzymes, hemodynamic variables, arterial hemogasometry, abdominal fluid volume, inflammatory markers, plasma nitrite/nitrate (NOx), plasma myeloperoxidase (MPO) and plasma malondialdehyde (MDA). One- and two-way analysis of variance (ANOVA) was performed, followed by the Bonferroni test (p < 0.05). RESULTS: amylase and lipase were three and 10-fold higher in the AP group. Myeloperoxidase activity was 50% higher in the AP group. The hemodynamic data indicated early hypovolemic shock followed by cardiogenic shock. Severe fluid translocation to the peritoneal cavity was observed. Plasma NOx remained unchanged. The MB+P group had a five-fold increase in MDA compared with the C group. CONCLUSION: preemptive application of MB in pigs with AP demonstrated no significant effects on hemodynamic and inflammatory variables. The use of MB is inadequate in cases of exponential NO release, and extreme caution must be exercised, given the increase in lipid peroxidation based on the malondialdehyde dosage.

Guanylate cyclase inhibition by methylene blue in circulatory shock caused by acute necrotizing pancreatitis: a word of caution based on a porcine model.

OBJECTIVE: To study the therapeutic application of guanylate cyclase inhibition by methylene blue in an experimental model of acute pancreatitis in pigs. METHODS: acute necrotizing pancreatitis was induced in anesthetized pigs by the retrograde infusion of 1 ml/kg of 5% sodium taurocholate and 8 U/kg enterokinase in the pancreatic duct. Three groups were studied (n = 5): control (C), pancreatitis (AP), and MB bolus followed by pancreatitis (MB+P). The data included serum and abdominal fluid enzymes, hemodynamic variables, arterial hemogasometry, abdominal fluid volume, inflammatory markers, plasma nitrite/nitrate (NOx), plasma myeloperoxidase (MPO) and plasma malondialdehyde (MDA). One- and two-way analysis of variance (ANOVA) was performed, followed by the Bonferroni test (p < 0.05). RESULTS: amylase and lipase were three and 10-fold higher in the AP group. Myeloperoxidase activity was 50% higher in the AP group. The hemodynamic data indicated early hypovolemic shock followed by cardiogenic shock. Severe fluid translocation to the peritoneal cavity was observed. Plasma NOx remained unchanged. The MB+P group had a five-fold increase in MDA compared with the C group. CONCLUSION: preemptive application of MB in pigs with AP demonstrated no significant effects on hemodynamic and inflammatory variables. The use of MB is inadequate in cases of exponential NO release, and extreme caution must be exercised, given the increase in lipid peroxidation based on the malondialdehyde dosage.

Oxidative stress is not associated with vascular dysfunction in a model of alloxan-induced diabetic rats.

OBJECTIVES: To verify if an experimental model of alloxan-diabetic rats promotes oxidative stress, reduces nitric oxide bioavailability and causes vascular dysfunction, and to evaluate the effect of N-acetylcysteine (NAC) on these parameters. METHODS: Alloxan-diabetic rats were treated or not with NAC for four weeks. Plasmatic levels of malondialdehyde (MDA) and nitrite/nitrate (NOx), the endothelial and inducible nitric oxide synthase (eNOS and iNOS) immunostaining and the vascular reactivity of aorta were compared among diabetic (D), treated diabetic (TD) and control (C) rats. RESULTS: MDA levels increased in D and TD. NOx levels did not differ among groups. Endothelial eNOS immunostaining reduced and adventitial iNOS increased in D and TD. The responsiveness of rings to acetylcholine, sodium nitroprusside, and phenylephrine did not differ among groups. CONCLUSIONS: NAC had no effect on the evaluated parameters and this experimental model did not promote vascular dysfunction despite the development of oxidative stress.

Oxidative stress is not associated with vascular dysfunction in a model of alloxan-induced diabetic rats / Estresse oxidativo não está associado à disfunção vascular em um modelo de diabetes induzida por aloxana em ratos

OBJECTIVES: To verify if an experimental model of alloxan-diabetic rats promotes oxidative stress, reduces nitric oxide bioavailability and causes vascular dysfunction, and to evaluate the effect of N-acetylcysteine (NAC) on these parameters. METHODS: Alloxan-diabetic rats were treated or not with NAC for four weeks. Plasmatic levels of malondialdehyde (MDA) and nitrite/nitrate (NOx), the endothelial and inducible nitric oxide synthase (eNOS and iNOS) immunostaining and the vascular reactivity of aorta were compared among diabetic (D), treated diabetic (TD) and control (C) rats. RESULTS: MDA levels increased in D and TD. NOx levels did not differ among groups. Endothelial eNOS immunostaining reduced and adventitial iNOS increased in D and TD. The responsiveness of rings to acetylcholine, sodium nitroprusside, and phenylephrine did not differ among groups. CONCLUSIONS: NAC had no effect on the evaluated parameters and this experimental model did not promote vascular dysfunction despite the development of oxidative stress.

OBJETIVOS: Verificar se um modelo experimental de diabetes por aloxana promove estresse oxidativo, reduz a disponibilidade de óxido nítrico e causa disfunção vascular, e avaliar o efeito da N-acetilcisteína (NAC) nesses parâmetros. MÉTODOS: Ratos diabéticos por aloxana foram tratados com NAC por quatro semanas. Níveis plasmáticos de malondialdeído (MDA) e nitrito/nitrato (NOx), imunomarcação para óxido nítrico sintase endotelial e induzida (eNOS e iNOS) e reatividade vascular da aorta foram comparados entre ratos diabéticos (D), diabéticos tratados (TD) e controles (C). RESULTADOS: O MDA aumentou nos grupos D e TD. O NOx não diferiu entre os grupos. A marcação da eNOS no endotélio reduziu e a da iNOS na adventícia aumentou nos grupos D e TD. A responsividade dos anéis vasculares à acetilcolina, nitroprussiato de sódio e fenilefrina não diferiu entre os grupos. CONCLUSÕES: A NAC não teve efeito sobre os parâmetros avaliados. Esse modelo experimental não promoveu disfunção vascular apesar do desenvolvimento de estresse oxidativo.

Exhaled breath condensate collection for nitrite dosage: a safe and low cost adaptation / Coleta do condensado do ar exalado pulmonar para a dosagem de nitrito: Uma adaptação segura e barata

Purpose: Standardization of a simple and low cost technique of exhaled breath condensate (EBC) collection to measure nitrite. Methods: Two devices were mounted in polystyrene boxes filled either with crushed ice/salt crystals or dry ice/crushed ice. Blood samples were stored at -70º C for posterior nitrite dosages by chemiluminescence and the Griess reaction. Results: a) The use of crushed ice/dry ice or salt revealed sufficient EBC room air collection, but was not efficient for patients under ventilation support; b) the method using crushed ice/salt collected greater EBC volumes, but the nitrite concentrations were not proportional to the volume collected; c) The EBC nitrite values were higher in the surgical group using both methods; d) In the surgical group the nasal clip use diminished the EBC nitrite concentrations in both methods. Conclusions: The exhaled breath condensate (EBC) methodology collection was efficient on room air breathing. Either cooling methods provided successful EBC collections showing that it is possible to diminish costs, and, amongst the two used methods, the one using crushed ice/salt crystals revealed better efficiency compared to the dry ice method.

Objetivo: Padronizar técnica simples e barata de coleta do condensado do ar exalado pulmonar (CEP) para medir nitrito. Métodos: Dois dispositivos foram montados em caixas de isopor e preenchidos com gelo picado/sal grosso ou gelo picado/gelo seco. Amostras de sangue foram armazenadas a -70º C para dosagem de nitrito por quimiluminescência e pela reação de Griess. Resultados: a) a utilização de gelo picado/gelo seco ou sal foi eficiente para a coleta em respiração espontânea, mas ineficiente durante ventilação mecânica; b) o método gelo picado/sal coletou volumes maiores, sem aumento proporcional do nitrito; c) os valores do nitrito foram mais elevados no grupo cirúrgico utilizando os dois métodos; d) no grupo cirúrgico com clipe nasal ocorreu diminuição do nitrito em ambos os métodos. Conclusões: A metodologia do condensado do ar exalado pulmonar (CEP) foi eficiente na coleta respirando em ar ambiente. Os dois métodos de congelamento foram eficientes mostrando que é possível diminuir os custos, e, entre os dois métodos utilizados, o uso de gelo picado/sal mostrou melhor eficiência quanto ao volume da coleta do CEP em comparação com o uso de gelo seco.

Exhaled breath condensate collection for nitrite dosage: a safe and low cost adaptation.

PURPOSE: Standardization of a simple and low cost technique of exhaled breath condensate (EBC) collection to measure nitrite. METHODS: Two devices were mounted in polystyrene boxes filled either with crushed ice/salt crystals or dry ice/crushed ice. Blood samples were stored at -70 degrees C for posterior nitrite dosages by chemiluminescence and the Griess reaction. RESULTS: a) The use of crushed ice/dry ice or salt revealed sufficient EBC room air collection, but was not efficient for patients under ventilation support; b) the method using crushed ice/salt collected greater EBC volumes, but the nitrite concentrations were not proportional to the volume collected; c) The EBC nitrite values were higher in the surgical group using both methods; d) In the surgical group the nasal clip use diminished the EBC nitrite concentrations in both methods. CONCLUSIONS: The exhaled breath condensate (EBC) methodology collection was efficient on room air breathing. Either cooling methods provided successful EBC collections showing that it is possible to diminish costs, and, amongst the two used methods, the one using crushed ice/salt crystals revealed better efficiency compared to the dry ice method.

Liver histological, portal flow and plasmatic nitric oxide alterations caused by biliary obstruction and drainage in rats.

PURPOSE: To evaluate liver alterations caused by biliary obstruction and drainage. METHODS: Thirty-nine male Wistar rats were randomly distributed in 4 groups: BO (n=18) bile duct ligation for 20 days, with a periodic evaluation of liver histological alterations, Doppler echography portal flow and measurements of NO and malondialdehyde (MDA); BO/DB (n=13) bile duct occlusion for 20 days followed by biliary drainage by choledochoduodenal anastomosis, 5 days follow-up, same BO group parameters evaluations; group CED (n=4) sham operation and portal flow evaluation trough 20 days; CHB (n=4) sham operation, with hepatic biopsy on 25th day and followed-up trough 25 days, by the same parameters of group BO, with exception of portal flow. Direct bilirubin (DB) and alkaline phosphatase (AP) were evaluated in the group BO, BO/DB and CHB. RESULTS: The bile duct ligation led to an increase of DB and AP, development of liver histological alterations, reduction of portal flow and increase of plasmatic NO and of MDA levels. The bile duct clearing resulted in a reduction of DB, AP, NO, MDA histological alterations and increase of portal flow. CONCLUSION: The biliary occlusion resulted in cholestasis and portal flow reduction, besides the increase of plasmatic NO and of hepatic MDA levels, and histological liver alterations, with a tendency of normalization after the bile duct clearing.

Methylene blue improves hemodynamic shock but increases lipoperoxidation in severe acute pancreatitis pig model.

PURPOSE: Study hemodynamic pattern and lipoperoxidation during methylene blue (MB) treatment on taurocholate - enterokinase induced acute pancreatitis (AP). METHODS: Thirty pigs were equally divided in control group; MB group; AP group; MB previous AP group; and MB after 90 min of induced AP group. MB was given iv in a bolus dose (2 mg.kg-1) followed by maintenance dose (2 mg.kg-1.h-1). Hemodynamic parameters were recorded continuously during 180 min by Swan-Ganz catheter. Blood samples were taken every 60 min to determine arterial and venous nitrate, malondialdehyde (MDA) and amylase. Pancreatic tissue was removed for histopathologic study. RESULTS: In AP group MBP and CO decreased over time 33% (p<0.05) and 52% (p<0.05), respectively. In MB previous induced-AP group, there was 70 minutes delay (p<0.05) to decrease MBP and CO. In MB group arterial and venous nitrite decreased (p<0.05) over time. MB infusion increased (p>0.05) serum MDA when associated to AP. After induced AP, MB did not reverse MBP and CO decrease. There was no difference in serum amylase and necro-hemorrhagic findings with MB treatment. CONCLUSIONS: In this taurocholate-induced AP model MB treatment delayed hemodynamic shock and decreases serum nitrate levels but increases serum MDA levels. No volemic replacement was done and it may have been a mitigated factor to a poor tissue perfusion and impairment microcirculation. Further investigations are needed to elucidate MB treatment role during AP treatment.

Evaluation of the mitochondrial respiration of cardiac myocytes in rats submitted to mechanical bile duct obstruction.

PURPOSE: The objective of the present study was to evaluate the capacity of the myocardium for energy production by the analysis of mitochondrial respiration in rats with jaundice submitted to bile duct ligature. METHODS: Sixteen male Wistar rats were divided into 2 Groups: Group SO submitted to nontherapeutic laparotomy (sham operation) and Group IC (icteric group) submitted to bile duct ligature. After 7 days, laparotomy was again performed in all animals for cardiac muscle extraction and analysis. Mitochondrial oxygen consumption was determined by stage 3 velocity and stage 4 velocity. The respiratory control ratio (RCR) was obtained by the ratio of stage 3 to stage 4 velocity. Statistical analysis was performed by the Mann-Whitney test, with the level of significance set at 5% (p<0.05). RESULTS: Statistical analysis revealed a significant drop in oxygen consumption during stage 3 mitochondrial respiration in group IC compared with SO, whereas the values obtained during stage 4 were basically identical for the two groups. Likewise, RCR values exhibited a significant reduction. CONCLUSION: The cellular respiration of the "jaundiced heart" is depressed. This was demonstrated by the reduced capacity of cardiac mitochondria to consume oxygen and synthesize ATP, supporting the idea of a latent cardiac impairment responsible for the hemodynamic decompensation occurring during cholestasis.

Plasma nitrate/nitrite (NOx) is not a useful biomarker to predict inherent cardiopulmonary bypass inflammatory response.

BACKGROUND AND AIM: There were strong evidences that nitric oxide has capital importance in the progressive vasodilatation associated with varied circulatory shock forms, including systemic inflammatory response syndrome (SIRS), in patients undergoing cardiac surgeries for cardiopulmonary bypass (CPB). If CPB procedures, per se, are the inciting stimulus for inflammation, plasma nitrate/nitrite (NOx) excretion would be expected to be higher in these patients rather than in patients operated without CPB. In consequence, we hypothesized that increased levels of NOx would be predictive for vasoplegic syndrome. METHODS: Thirty patients were assigned to three groups: Group 1--coronary artery bypass graft (CABG) roller pump CPB; Group 2--CABG centrifugal vortex pump CPB; and Group 3--heart valve surgery roller pump CPB. Sampling of venous blood for chemiluminescence plasma NOx dosage was achieved at the following time points: (1) before anesthesia induction; (2) after anesthesia induction; (3) before heparin infusion; (4) after heparin infusion; (5) CPB-30 minutes; (6) CPB-60 minutes; (7) before protamine infusion; (8) after protamine infusion; and (9) on return to the recovery area. RESULTS: There were no intergroup differences regarding age and anesthetic regimen, and the number of arteries grafted was not different between the CABG groups. There were no NOx statistic differences, neither among the three groups of patients or among the surgery time. In addition, there was no correlation among NOx, lactate, and hemoglobin. CONCLUSIONS: Considering the inflammatory process intrinsic to CPB, this study reinforces the idea that plasma NOx is not useful as a biomarker of inflammatory response onset, which may or may not lead to SIRS and/or vasoplegic syndrome.

Compound 48/80 induces endothelium-dependent and histamine release-independent relaxation in rabbit aorta.

Compound 48/80 (C48/80) is a synthetic condensation product of N-methyl-p-methoxyphenethylamine with formaldehyde and is an experimental drug used since the 1950s to induce anaphylactic shock through histamine release. This study was carried out to further elucidate the mechanism by which this drug induces nitric oxide (NO) release. Our specific goals were: (a) to verify if C48/80's relaxation occurs through the stimulation of histamine receptors; (b) to evaluate the endothelium-dependent relaxation induced by C48/80; (c) to identify NO as the endothelium-relaxing factor released by C48/80; (d) to identify the NO synthase (NOS) responsible for NO release; and (e) to verify if the relaxation induced by C48/80 is calcium and cyclic guanidine monophosphate (cGMP) dependent. Rabbit aorta segments, with and without endothelium, were suspended in organ chambers (25ml) filled with Krebs solution maintained at 37 degrees C, bubbled with 95% O(2)/5% CO(2) (pH 7.4). Phenylephrine was used to contract the segments. Other protocol drugs included H(1)- and H(2)-receptor antagonists, cyclooxygenase, NOS, guanylyl cyclase and phospholipase C (PLC) inhibitors. Endothelium-dependent relaxation induced by C48/80 was also studied in calcium-free Krebs solution associated with a calcium chelator. In summary, our investigation demonstrated that the C48/80 vasodilating action: (a) does not depend on H(1) and H(2) histamine receptors; (b) is NO endothelium-dependent; (c) is dependent on the endothelial constitutive NOS (NOS-3) isoform activation; (d) is cGMP-dependent; and that NOS-3 activation by C48/80: (a) is independent of PLC up to 25mug/ml and (b) is partially dependent of this lipase in higher doses.

Liver histological, portal flow and plasmatic nitric oxide alterations caused by biliary obstruction and drainage in rats / Alterações histológicas, do fluxo portal e do óxido nítrico plasmático em ratos submetidos à obstrução/desobstrução biliar

PURPOSE: To evaluate liver alterations caused by biliary obstruction and drainage. METHODS: Thirty-nine male Wistar rats were randomly distributed in 4 groups: BO (n=18) bile duct ligation for 20 days, with a periodic evaluation of liver histological alterations, Doppler echography portal flow and measurements of NO and malondialdehyde (MDA); BO/DB (n=13) bile duct occlusion for 20 days followed by biliary drainage by choledochoduodenal anastomosis, 5 days follow-up, same BO group parameters evaluations; group CED (n=4) sham operation and portal flow evaluation trough 20 days; CHB (n=4) sham operation, with hepatic biopsy on 25th day and followed-up trough 25 days, by the same parameters of group BO, with exception of portal flow. Direct bilirubin (DB) and alkaline phosphatase (AP) were evaluated in the group BO, BO/DB and CHB. RESULTS: The bile duct ligation led to an increase of DB and AP, development of liver histological alterations, reduction of portal flow and increase of plasmatic NO and of MDA levels. The bile duct clearing resulted in a reduction of DB, AP, NO, MDA histological alterations and increase of portal flow. CONCLUSION: The biliary occlusion resulted in cholestasis and portal flow reduction, besides the increase of plasmatic NO and of hepatic MDA levels, and histological liver alterations, with a tendency of normalization after the bile duct clearing.

OBJETIVO: Avaliar alterações hepáticas resultantes do processo de obstrução/desobstrução biliar. MÉTODOS: Trinta e nove ratos Wistar foram distribuídos aleatoriamente em 4 grupos: OB (n=18), oclusão biliar, seguimento de 20 dias, avaliação das alterações histológicas hepáticas, do fluxo portal e dosagens de NO e de malondialdeído (MDA); grupo OB/DB (n=13) oclusão biliar por 20 dias seguida de desobstrução biliar por anastomose colédoco-duodenal, seguimento por 5 dias e avaliação dos mesmos parâmetros do grupo BO; grupo CED (n=4) operação simulada, avaliação do fluxo portal e seguimento por 25 dias; grupo CHB (n=4) operação simulada com biópsia hepática no 25º dia, e seguido por 25 dias com avaliação periódica dos mesmos parâmetros do grupo BO, com exceção da ecografia Doppler. Nos grupos BO, OB/DB e CHB foram avaliadas também a bilirrubina direta (BD) e a fosfatase alcalina (FA). RESULTADOS: A oclusão do colédoco causou aumento da BD e da FA, desenvolvimento de alterações hepáticas, redução do fluxo portal, com aumentos do NO plasmático e do MDA. A desobstrução biliar resultou na redução da BD, da FA, das alterações hepáticas, aumento do fluxo portal e redução do NO e do MDA. CONCLUSÃO: A obstrução biliar resultou em colestase, alterações histológicas hepáticas, diminuição do fluxo portal, aumentos do NO plasmático e MDA hepático, com tendência à normalização após a desobstrução biliar.

Methylene blue improves hemodynamic shock but increases lipoperoxidation in severe acute pancreatitis pig model / Azul de metileno melhora as condições hemodinâmicas do choque circulatório, mas aumenta a peroxidação lipídica em um modelo suino de pancreatite aguda grave

PURPOSE: Study hemodynamic pattern and lipoperoxidation during methylene blue (MB) treatment on taurocholate - enterokinase induced acute pancreatitis (AP). METHODS: Thirty pigs were equally divided in control group; MB group; AP group; MB previous AP group; and MB after 90 min of induced AP group. MB was given iv in a bolus dose (2mg.kg-1) followed by maintenance dose (2 mg.kg-1.h-1). Hemodynamic parameters were recorded continuously during 180 min by Swan-Ganz catheter. Blood samples were taken every 60 min to determine arterial and venous nitrate, malondialdehyde (MDA) and amylase. Pancreatic tissue was removed for histopathologic study. RESULTS: In AP group MBP and CO decreased over time 33 percent (p<0.05) and 52 percent (p<0.05), respectively. In MB previous induced-AP group, there was 70 minutes delay (p<0.05) to decrease MBP and CO. In MB group arterial and venous nitrite decreased (p<0.05) over time. MB infusion increased (p>0.05) serum MDA when associated to AP. After induced AP, MB did not reverse MBP and CO decrease. There was no difference in serum amylase and necro-hemorrhagic findings with MB treatment. CONCLUSIONS: In this taurocholate-induced AP model MB treatment delayed hemodynamic shock and decreases serum nitrate levels but increases serum MDA levels. No volemic replacement was done and it may have been a mitigated factor to a poor tissue perfusion and impairment microcirculation. Further investigations are needed to elucidate MB treatment role during AP treatment.

OBJETIVO: estudar o perfil hemodinâmico e a lipoperoxidação durante o tratamento com azul de metileno (AM) de pancreatite aguda (PA) induzida por taurocolato-enteroquinase. MÉTODOS: Trinta porcos foram igualmente divididos em: grupo controle, grupo AM; grupo PA; grupo AM prévio à PA; grupo AM após 90 minutos após a indução da PA. O AM foi administrado sob a forma de bolus EV (2mg.kg-1) seguido por dose de manutenção (2 mg.kg-1.h-1). Os parâmetros hemodinâmicos foram registrados continuamente durante 180 min com auxílio de cateter de Swan-Ganz. Amostras sanguíneas foram colhidas a cada 60 min para a determinação arterial e venosa de nitrato, malondialdeido (MDA) and amilase. Removeu-se tecido pancreático para estudo histopatológico. RESULTADOS: No grupo PA a pressão arterial media (PAM) e o débito cardíaco (DC) diminuíram respectivamente 33 por cento (p<0.05) e 52 por cento (p<0.05) no decorrer do tempo. No grupo AM prévio à indução da PA ocorreu 70 minutes de demora (p<0.05) para as diminuições da PAM e DC. No grupo AM houve diminuição temporal do nitrato arterial e venoso (p<0.05). A infusão de AM aumentou os valores de MDA sérico quando associado a PA (p>0.05). Após a indução da PA a infusão de AM não reverteu as quedas da PA e DC. Não houve diferenças nos níveis de amilase sérica e achados histológicos com o tratamento com o azul de metileno. CONCLUSÕES: No presente modelo de PA induzida por taurocolato o AM retardou o desenvolvimento do choque circulatório, diminuiu os níveis de nitrato mas aumentou os níveis de MDA. Não se realizou nenhum tipo de reposição volêmica que poderia melhorar a perfusão tecidual e melhora da microcirculação. Investigações adicionais são necessárias para elucidar o papel terapêutico do AM no tratamento da PA aguda.

Evaluation of the mitochondrial respiration of cardiac myocytes in rats submitted to mechanical bile duct obstruction / Avaliação da respiração mitocondrial de miócitos cardíacos em ratos ictéricos sumetidos à obstrução do ducto biliar

PURPOSE: The objective of the present study was to evaluate the capacity of the myocardium for energy production by the analysis of mitochondrial respiration in rats with jaundice submitted to bile duct ligature. METHODS: Sixteen male Wistar rats were divided into 2 Groups: Group SO submitted to nontherapeutic laparotomy (sham operation) and Group IC (icteric group) submitted to bile duct ligature. After 7 days, laparotomy was again performed in all animals for cardiac muscle extraction and analysis. Mitochondrial oxygen consumption was determined by stage 3 velocity and stage 4 velocity. The respiratory control ratio (RCR) was obtained by the ratio of stage 3 to stage 4 velocity. Statistical analysis was performed by the Mann-Whitney test, with the level of significance set at 5 percent (p<0.05). RESULTS: Statistical analysis revealed a significant drop in oxygen consumption during stage 3 mitochondrial respiration in group IC compared with SO, whereas the values obtained during stage 4 were basically identical for the two groups. Likewise, RCR values exhibited a significant reduction. CONCLUSION: The cellular respiration of the "jaundiced heart" is depressed. This was demonstrated by the reduced capacity of cardiac mitochondria to consume oxygen and synthesize ATP, supporting the idea of a latent cardiac impairment responsible for the hemodynamic decompensation occurring during cholestasis.

OBJETIVO: A proposta deste trabalho é avaliar a capacidade de produção energética do miocárdio mediante análise da respiração mitocondrial em ratos ictéricos submetidos à ligadura do ducto biliar. MÉTODOS: Foram utilizados 16 ratos Wistar machos divididos em 2 Grupos: Grupo SO , os quais foram submetidos à Laparotomia branca e Grupo IC, os quais sofreram ligadura do ducto biliar para o desenvolvimento de icterícia obstrutiva. Todos os animais após 7 dias de cirurgia foram submetidos à nova laparotomia para extração e análise do músculo cardíaco. O consumo de oxigênio pelas mitocôndrias foi determinado pela velocidade do estado 3 e velocidade do estado 4. A razão do controle respiratório (RCR) foi obtida pela relação entre as velocidades dos estados 3 e 4. A análise estatística foi feita pelo teste de Mann-Whitney com nível de significância de 5 por cento (p<0.05). RESULTADOS: Observou-se queda estatisticamente significante nos valores do consumo de oxigênio do estado 3 da respiração mitocondrial no grupo IC em relação ao SO, no entanto os valores para estado 4 permaneceram basicamente inalterados entre os grupos. Os valores de RCR entre os grupos também apresentaram diminuição significativa. CONCLUSÃO: A respiração celular do 'coração ictérico' está deprimida em decorrência da redução da capacidade da mitocôndria cardíaca em consumir oxigênio e sintetizar ATP, o que pode contribuir para a disfunção cardiovascular na vigência da colestase.