Force patterns of hypoxic myocardium applied to oxygenated muscle preparations: Comparison with effects of regional ischemia on the contraction of non-ischemic myocardium

Objective: To examine the basis for local wall motion abnormalities commonly seen in patients with ischemic heart disease, computer-controlled isolated muscle studies were carried out. Methods: Force patterns of physiologically sequenced contractions (PSCs) from rat left ventricular muscle preparations under well-oxygenated conditions and during periods of hypoxia and reoxygenation were recorded and stored in a computer. Force patterns of hypoxic-reoxygenating and oxygenated myocardium were applied to oxygenated and hypoxic-reoxygenating myocardium, respectively. Results: Observed patterns of shortening and lengthening closely resemble those obtained from ischemic and non-ischemic myocardial segments using ultrasonic crystals in intact dog hearts during coronary occlusion and reperfusion, and are similar to findings reported in angiographic studies of humans with coronary artery disease. Conclusion: The current study, demonstrating motions of oxygenated isolated muscle preparations which are similar to those in perfused segments of intact hearts with regional ischemia, supports the concept that the multiple motions of both ischemic and non-ischemic segments seen in regional myocardial disease can be explained by interactions of strongly and weakly contracting muscle during the physiologic cardiac cycle.

Effect of allopurinol on the kidney function, histology and injury biomarker (NGAL, IL 18) levels in uninephrectomised rats subjected to ischaemia-reperfusion injury

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Perfil eletroforético do proteinograma sérico de eqüinos com obstrução experimental do cólon menor

Avaliaram-se as alterações do proteinograma sérico de eqüinos submetidos à isquemia e reperfusão do cólon menor por distensão intraluminal. Foram utilizados 10 animais submetidos à laparotomia pelo flanco, em posição quadrupedal, para a indução de obstrução no cólon menor durante um período de quatro horas. Cinco animais foram instrumentados, mas sem distensão (grupo controle - G1). em cinco outros animais, foi realizada isquemia mural por distensão do cólon menor via manguito inflado com 40mmHg (grupo distendido - G2). Foram colhidas amostras de sangue antes da intervenção cirúrgica (M1), com 4 horas da colocação do manguito (M2) e com 3 horas (M3) e 12 horas (M4) de reperfusão. Após centrifugação e fracionamento das amostras, as proteínas de fase aguda foram separadas por eletroforese em gel de poliacrilamida contendo SDS-PAGE, e suas concentrações determinadas por densitometria computadorizada. Foram encontradas 19 proteínas no fracionamento eletroforético, com peso molecular variando de 185.000 a 14.000 Daltons (Da). Os pesos moleculares encontrados, correspondentes às proteínas mais conhecidas, foram ceruloplasmina, 130.000 Da; proteína C-reativa, 122.000 Da; transferrina, 85.000 Da; α1-antitripsina, 61.000 Da; haptoglobina, 47.000 Da; e glicoproteína ácida, 40.000 Da. Os resultados mostram que proteínas de fase aguda se alteram após o trauma cirúrgico.

Hemograma e hemogasometria de eqüinos submetidos à obstrução experimental de jejuno

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Alterações morfométricas no plexo mioentérico do cólon menor equino distendido experimentalmente

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Acute renal ischemia model in dogs: Effects of metoprolol

Introduction: To study the functional and hystological alterations in dog kidneys submitted to total ischemia for thirty minutes and the possible metoprolol protective action. Material and methods: Sixteen dogs anesthetized with sodium pentobarbital (SP) were studied and divided into two groups: G1-8 dogs submitted to left nephrectomy and right renal artery clamping for thirty minutes, and G2-8 dogs submitted to the same procedures of G1 and to the administration of 0.5 mg.kg(-1) metoprolol before ischemia. Attributes of renal function were studied. Results: There was acute tubular necrosis and a decrease of renal blood flow and glomerular filtration, and a increase of renal vascular resistance in both groups. Conclusion: the thirty minute renal ischemia appears to have determined the alterations found in the renal function and hystology in both groups. Metoprolol, used in G2, as to the time and dose applied didn't protect the kidney from the ischemic episode.

Influence of S(+)-ketamine analgesia in renal intraoperative ischemia: histological study in rats

OBJETIVO: Investigar, em ratos, o efeito da S(+)cetamina na histologia renal após hemorragia intra-operatória. MÉTODOS: Vinte ratos Wistar machos, anestesiados com pentobarbital sódico, foram divididos, aleatoriamente, em 2 grupos: G1 - controle (n=10) e G2 - S(+)cetamina (n=10), submetidos a hemorragia de 30% da volemia em 3 momentos (10% a cada 10 min) 60 min após anestesia. G2 recebeu S(+)cetamina, 15 mg. kg-1, i.m., 5 min após anestesia e 55 min antes do 1.º momento de hemorragia (M1). Foram monitorizadas a pressão arterial média (PAM), temperatura retal (T) e freqüência cardíaca. Os animais foram sacrificados (M4) 30 min após o 3.º momento de hemorragia (M3). Os rins e o sangue das hemorragias foram utilizados para estudo histológico e do hematócrito (Ht). RESULTADOS: Houve redução significativa da PAM, T e Ht. Na histologia, G1=G2 na dilatação tubular, congestão e necrose. A soma total dos escores foi significativamente diferente e G2>G1. CONCLUSÃO: Hemorragia e hipotensão determinaram alterações na histologia renal. O aumento da concentração sangüínea de catecolaminas provavelmente determinou escores mais altos de alterações histológicas com o uso de S(+)cetamina.

Evaluation of Hemodynamic, Metabolic, and Electrolytic Changes After Graft Reperfusion in a Porcine Model of Intestinal Transplantation

Background. We sought to establish an anesthetic protocol to evaluate the hemodynamic, metabolic, and electrolytic changes after graft reperfusion in pigs undergoing orthotopic intestinal transplant (ITX).Methods. Fifteen pigs were distributed into two groups: GI (n = 6), without immunosuppression, and GII (n = 9), immunosuppressed before surgery with tacrolimus (0.3 mg/kg). The animals were premedicated at 1 hour before surgery with IM acepromazine (0.1 mg/kg), morphine (0.4 mg/kg), ketamine (10 mg/kg), and atropine (0.044 mg/kg IM). Anesthesia induction used equal proportions of diazepam and ketamine (0.1-0.15 mL/kg/IV) and for maintenance in IV infusion of xylazine (1 mg/mL), ketamine (2 mg/mL), and guaiacol glyceryl ether 5% (50 mg/mL), diluted in 250 mL of 5% glucose solution. In addition, recipient pigs were treated with isofluorane inhalation. Heart rate (HR), systolic (SAP), mean (MAP), and diastolic (DAP) arterial pressure, pulse oximetry, respiratory frequency (f), capnography, body temperature (T), blood gas analysis (pH, PaCO(2), PaO(2), base excess, BE; HCO(3)(-), SatO(2)), serum potassium (K), calcium (Ca), sodium, hematocrit (Hct), and glucose (Glu) were measured at four times; MO: after incision (basal value); M1: 10 minutes before reperfusion; and M2 and M3: 10 and 20 minutes after graft reperfusion.Results. All groups behaved in a similar pattern. There was significant hypotension after graft reperfusion in GI and GII (M2 = 56.2 +/- 6.4 and M3 = 57.2 +/- 8.3 mm Hg and M2 = 65.7 +/- 10.2 and M3 = 67.8 +/- 16.8 mm Hg, respectively), accompanied by elevated HR. The ETCO(2) was elevated at M2 (42 mm Hg) and M3 (40 mm Hg). Metabolic acidosis was observed after reperfusion, with significant increase in K levels.Conclusion. The anesthetic protocol for donors and recipients was safe to perform the procedure, allowing control of hemodynamic and metabolic changes after reperfusion without differences regarding immunosuppression.

Cerebral ischemia as initial neurological manifestation of atrial myxoma: case report

Infartos cerebrais de etiologia cardíaca são observados em cerca de 20% dos pacientes com acidente vascular cerebral isquêmico. Infarto cerebral ocorre como manifestação clínica inicial em um terço dos casos de mixoma atrial. Embora quase metade dos pacientes com mixoma atrial apresente alteração ao exame neurológico, infarto cerebral não hemorrágico é visto na tomografia computadorizada em praticamente todos os casos. Os autores apresentam o caso de uma paciente, cuja primeira manifestação clínica do mixoma atrial foi um acidente vascular cerebral isquêmico e chamam a atenção para a possibilidade de infarto cerebral silencioso em pacientes portadores de mixoma atrial.

Hypoxic-preconditioning induces neuroprotection against hypoxia-ischemia in newborn piglet brain

Preconditioning-induced ischemic tolerance has been documented in the newborn brain, however, the signaling mechanisms of this preconditioning require further elucidation. The aims of this study were to develop a hypoxic-preconditioning (PC) model of ischemic tolerance in the newborn piglet, which emulates important clinical similarities to human situation of birth asphyxia, and to characterize some of the molecular mechanisms shown to be implicated in PC-induced neuroprotection in rodent models. One day old piglets were subjected to PC (8% O(2)/92% N(2)) for 3 h and 24 h later were exposed to hypoxia-ischemia (HI) produced by a combination of hypoxia (5% FiO(2)) for a period of 30 min and ischemia induced by a period of hypotension (10 min of reduced mean arterial blood pressure; 70% of baseline). Neuropathologic analysis and unbiased stereology, conducted at 24 h, 3 and 7 days of recovery following HI, indicated a substantial reduction in the severity of brain damage in PC piglets compared to non-PC piglets (P<0.05). PC significantly increased the mRNA expression of hypoxia-inducible factor-1 alpha (HIF-1 alpha) and its target gene, vascular endothelial growth factor (VEGF) at 0 h, 6 h, 24 h, 3 and 7 days of recovery. Immunoblot analysis demonstrated that PC resulted in HIF-1 alpha protein stabilization and accumulation in nuclear extracts of cerebral cortex of newborn piglet brain compared to normoxic controls. Protein levels of VEGF increased in a time-dependent manner in both cortex and hippocampus following PC. Double-immunolabeling indicated that VEGF is mainly expressed in neurons, endothelial cells and astroglia. Our study demonstrates for the first time the protective efficacy of PC against hypoxic-ischemic injury in newborn piglet model, which recapitulates many pathophysiological features of asphyxiated human neonates. Furthermore, as has been shown in rodent models of preconditioning, our results suggest that PC-induced protection in neonatal piglets may involve upregulation of VEGF. (C) 2011 Elsevier B.V. All rights reserved.

Cold Renal Ischemia: Comparison of Efficacy Between Two Techniques of Cooling, in a Swine Model

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ischaemia and reperfusion effects on skeletal muscle tissue: morphological and histochemical studies

This was a study on the oxidative stress due to ischaemia (I) and reperfusion (R) in skeletal muscle tissue. Using a tourniquet, groups of rats were submitted to ischaemia for 4 h, followed by different reperfusion periods. The animals were divided in four groups: control; 4 h of ischaemia (IR); 4 h of ischaemia plus 1 h reperfusion (IR-1 h); 4 h of ischaemia plus 24 h reperfusion (IR-24 h); and 4 h of ischaemia plus 72 h reperfusion (IR-72 h). At the end of the procedures, samples of soleus muscle were collected and frozen in n-hexane at -70 degrees C. Cryostat sections were submitted to haematoxylin-eosin, succinate dehydrogenase (SDH) and nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR) stains. An additional muscle sample was processed for electron microscopy. No alterations were found in control animals. IR group showed fibres had normal aspect besides some round, acidophilic and hypertrophic fibres. There were several fibres with angular outlines and smaller diameters in this group compared with control group. NADH-TR/SDH reaction was moderately intense in most fibres. In some fibres, cytoplasm showed areas without activity and other fibres had very intense reactivity. IR-1 h group showed oedema hypercontracted fibres with disorganized myofibrils, mitochondria with focal lesions and dilated sarcoplasmic reticulum. NADH-TR/SDH reaction was moderate to weak. IR-24 h showed intense inflammatory infiltrate in the endomysium and perimysium. NADH-TR/SDH reaction was similar to IR-1 h. IR-72 h showed necrotic fibres, areas with inflammatory infiltrate, reduced muscle fibres at different stages of necrosis and phagocytosis, and many small round and basophilic fibres characterizing a regeneration process. NADH-TR/SDH reaction was weak to negative. Our results suggest that ischaemia and the subsequent 1-, 24- and 72-h reperfusions induced progressive histological damage. Although progressive, it may be reversible because there were ultrastructural signs of recovery after 72-h reperfusion. This recovery could in part be due to the low oxidative stress identified by the morphological and histochemical analysis.

Avaliação de dois modelos experimentais de isquemia e reperfusão cerebral em ratos com oclusão temporária carotídea associada ou não à oclusão vertebral

OBJETIVO: Avaliar a reprodutibilidade de dois modelos experimentais de isquemia e reperfusão cerebral. MÉTODOS: 60 ratos foram distribuídos, aleatoriamente, em três grupos experimentais, com 20 animais cada: I - pinçamento temporário de artéria carótida esquerda; II - cauterização prévia das artérias vertebrais e pinçamento temporário da artéria carótida esquerda; simulado - sem isquemia nem reperfusão. Todos os animais tiveram oclusão definitiva de artéria carótida direita e os três grupos foram subdivididos em dois períodos de reperfusão: A - 60 minutos e B - 120 minutos. Os parâmetros verificados foram: medidas de pressão arterial média sistêmica e fluxo sangüíneo carotídeo; medida de malondialdeído cerebral através do teste TBARS e avaliação histológica do hemisfério cerebral submetido à isquemia e reperfusão. Foi feito também um estudo complementar com angiografia cerebral em 5 animais adicionais. RESULTADOS: Não houve diferenças significativas nas dosagens de malondialdeído cerebral e na freqüência e gravidade das alterações histológicas cerebrais entre os três grupos. Nos grupos GI e GII, a PAM foi significantemente maior no período de isquemia. O fluxo sangüíneo entre os períodos pré e pós-pinçamento aumentou nos grupos IA e IIB, diminuiu no grupo IB e no grupo IIA manteve-se inalterado. As angiografias do estudo complementar mostraram aporte sangüíneo para cérebro através de circulação colateral. CONCLUSÃO: Os modelos de isquemia e reperfusão estudados não demonstraram alterações consistentes de marcadores de lesão cerebral, seja quanto à produção de lipoperóxidos ou de lesões histológicas.

Effects of lisinopril on experimental ischemia in rats. Influence of infarct size

OBJECTIVE - Angiotensin-converting enzyme inhibitors (ACEIs) have gained importance in preventing or attenuating the process of ventricular remodeling after myocardial infarction. The significance of infarct size in regard to the response to ACEIs, however, is controversial. This study aimed to analyze the effects of lisinopril on mortality rate, cardiac function, degree of cardiac hypertrophy and fibrosis in rats with different infarct sizes. METHODS - Lisinopril (20 mg/kg/day) dissolved in drinking water was administered to rats immediately after coronary artery occlusion. After being sacrificed, the infarcted animals were divided into two groups: one group of animals with small infarcts (< 40% of the left ventricle) and another group of animals with large infarcts (> 40% of the left ventricle). RESULTS - The mortality rate was 31.7% in treated rats and 47% in the untreated rats. There was no statistical difference between the groups with small and large infarcts in regard to myocardial concentration of hydroxyproline. In small infarcts, the treatment attenuated the heart dysfunction characterized by lower levels of blood pressure and lower values of the first derivative of pressure and of the negative derivative of pressure. The degree of hypertrophy was also attenuated in small infarcts. In regard to large infarcts, no differences between the groups were observed. CONCLUSION - Treatment with the ACEIs had no effect on mortality rate and on the amount of fibrosis. The protective effect of lisinopril on heart function and on the degree of hypertrophy could only be detected in small infarcts

FUNCTIONAL AND ULTRASTRUCTURAL EVALUATION OF MYOCARDIAL PROTECTION PROVIDED BY INTERMITTENT CORONARY SINUS PERFUSION IN THE ISOLATED DOG HEART

1. The protection offered by intermittent perfusion of of cardioplegic solution through the coronary sinus was investigated in isovolumic blood-perfused dog heart preparations submitted to 60 min of ischemia and 45 min of reperfusion.2. The preparations were divided into three treatment groups: a) coronary sinus, consisting of preparations (N = 10) perfused through the coronary sinus under 40 cm water pressure; b) aortic, consisting of preparations (N = 10) perfused through the aortic stump under 100 mmHg pressure; c) control, consisting of hearts (N = 9) that were not perfused with cardioplegic solution.3. Properties of contractile capacity and relaxation were markedly impaired in the control group but were preserved to a comparable extent in the groups perfused with cardioplegic solution through the aorta and coronary sinus. Developed pressure decreased in the control group (before ischemia: 70 +/- 5.5 mmHg; after reperfusion: 35 +/- 12 mmHg; P < 0.05) and didn't vary in the aortic group (from 69 +/- 4 mmHg to 65 +/- 13 mmHg; P > 0.05) and coronary sinus group (from 69 +/- 4.6 mmHg to 60 +/- 10 mmHg; P > 0.05). Myocardial relaxation was evaluated by the +/- dp/dt ratio. In the control group there was impairment of myocardial relaxation as indicated by an increase of this index after reperfusion (from 1.05 +/- 0.05 to 1.46 +/- 0.23; P < 0.05), whereas in the aortic (from 1.10 +/- 0.13 to 1.15 +/- 0.20; P > 0.05) and the coronary sinus (from 1.03 +/- 0.14 to 1.08 +/- 0.16; P > 0.05) groups there was no variation. Ultrastructural changes in the myocardium were negligible in all three groups at the end of reperfusion.4. We conclude that intermittent perfusion of a hypothermic cardioplegic solution through the coronary sinus is effective for the protection of the myocardium during total ischemia.