Is coronary sinus blood oxygen tension behavior determined by myocardial oxygen tension variation during cardiac reperfusion?

The relationship between coronary sinus blood oxygen tension (CSPO 2) and myocardial oxygen tension (MPO 2) variations during cardiac ischemia and reperfusion was studied in anesthetized open-chest dogs. Oxygen tension was measured by a polarographic method. Ischemia resulted in a slightly decreased CSPO 2 and a more pronounced reduction of MPO 2. After reperfusion the CSPO 2 rose rapidly and transiently before it returned gradually to the control level. By contrast, during the recovery period, the MPO 2 increased slowly, with recovery occurring long after the peak of CSPO 2. These data suggest that during the reperfusion phase, the CSPO 2 variation is probably due to opening of the myocardial arteriovenous shunts instead of an increase of flow through the myocardial capillary bed.

Anatomic data of the human coronary sinus

The authors studied the formation, tributaries, lenght and the ostium of the coronary sinus, as well as the relationship of the venous walls to the myocardium and to the epicardium. The observations were made out of 143 hearts of subjects of different ages, and it was found that the most frequent display of the coronary sinus valve was a semilunar form (52 adults, 15 youngsters, 2 children, 3 newborn); it was also found valves in a cribiform or septal form. The absence of the valve of coronary sinus was noted in 53 cases (42 adults, 9 youngsters, 2 newborn). The valve of Vieussens was found, in some cases, at the level of the transition between the great cardiac vein and the coronary sinus, as well as others single or double parietal venous valves. The action of the valve of coronary sinus is also discussed by the authors.

Nickel chloride: potential accumulation from the airway. Toxicokinetics in rats.

The rate removal of nickel from the airway was measured in vivo. Removal in vivo was studied by intratracheal injection of nickel chloride solutions. Regardless of time after injection, the lungs and heart retained the greatest concentration of nickel and 40 days after 1.68 mumol administration they were the organs where nickel was still significantly measurable. The slow removal of nickel may indicate the presence of high affinity binding sites in the lung. Nickel can interact with others metals, such as copper and zinc, so that nickel exposure may have public health implications.

Efeito do envelhecimento sobre o comportamento mecânico dos músculos papilares de ratos Wistar.

PURPOSE--To evaluate the effects of age on mechanical performance of rat myocardium. METHODS--Left ventricular papillary muscles were isolated from male Wistar rats at 1, 3, 6 and 12 months of age. Muscles were studied isometrically and isotonically, stimulated at 0.2 Hz, perfused with Krebs-Henseleit solution having an external calcium concentration of 2.52 mM, and maintained at 28 degrees C. RESULTS--Peak isometric developed tension was significantly higher in 1 month than 3, 6 and 12 months. Peak rate of isometric tension rise decreased substantially between 1, 3 and 12 months. Time to peak isometric developed tension showed a significant increase of both 3 and 12 months of age. Time to half relaxation increased significantly from 3 to 6 and from 3 to 12 months. Maximum rate of tension decline decreased from 3 to 6 and from 3 to 12 months. No difference in resting tension was noted among any group. Isotonically, peak shortening and time to peak shortening increased from 1 to 3 months of age. Time to half re-lengthening increased from 3 to 6 and from 3 to 12 months of age. No difference in peak shortening velocity, peak relaxation velocity and relative change in muscle length was noted among any groups. CONCLUSION--The maturation affects the mechanical performance of cardiac muscle.

INFLUENCIA DO ACRESCIMO DE MANITOL A SOLUCAO NUTRIENTE NO DESEMPENHO MECANICO E NO GRAU DE EDEMA MIOCARDICO DE CORACOES ISOLADOS DE RATOS

Purpose - To analyse the influence of mannitol added to Krebs-Henseleit (KH) solution on the myocardium edema and myocardial function. Methods - Isolated rat heart under isovolumetric contractions studied according to Langendorff's technique were perfused with KH solution at constant flow during 90 min. The coronary perfusion pressure, diastolic and systolic pressures were recorded at every 15 min. At the end of the experiment, myocardium water content was measured in hearts perfused with KH solution (group I, n = 9) and in hearts perfused with KH solution plus 8 mM mannitol (group II, n = 8). These results were compared to non-perfused control heart (n = 9). Results - Myocardial water content was statistically higher in group I (80.8 ± 1.3%) compared to group II (78.1 ± 0.7%) and control group (75.5 ± 0.5%). Systolic arterial pressure was statistically higher in group I (86.2 ± 11.5 mmHg) compared to group II (72.7 ± 21.1 mmHg). There was no difference in the diastolic pressure between the two groups. Coronary perfusion pressure (Pp) increased progressively during the experiment in both groups. However, Pp was lower in group II than in group I. Conclusion - Mannitol added to KH solution significantly attenuates the myocardium edema in the isolated perfused rat heart.

Patologia do Coração na AIDS. Estudo de 73 Necropsias Consecutivas

Purpose - To study the incidence and the etiology of the cardiac lesions in AIDS patients. Methods - The autopsy protocols and the filled slides of the heart from 73 consecutive AIDS patients were reviewed. There were, at least, 2 slides of each heart stained by haematoxylin-eosin; when indicated, Ziehl-Nielsen, Gram and Gomori Grocott stains were used. Results - No cause of death was assigned to the heart. There was involvement of the heart in 66 (90%) cases. Marked atrophy of cardiac fibers with or without lipomatosis was observed in 38 patients. Interstitial infiltrates of myocardium were present in 38 necropsies and in 13 of these cases a probable pathogen was demonstrated: cryptococcus neoforms in three cases and mycobacteria tuberculosis, atypical mycobacteria, toxoplasma gondii, trypanosoma cruzi and cytomegalovirus in two cases each. Bacterial endocarditis was found in 4 autopsies and Kaposi sarcome in one. The pericardium was involved in 22 cases; in 12 there was only non specific mononuclear infiltration. Conclusion - Autopsy examination of the heart from AIDS patients revealed frequent pathologic involvement.

Structural characteristics of the superior venae cavae wall at the intrapericardium segment in adults and aging individuals

The authors admit that the conjunctive-muscular constitution of the walls of the superior venae cavae throughout the length of the intrapericardium segment and the debouchement in the right atrium, associated with the presence of a myocardium sheath can be made up of a functional device of sphincter form able to act on the control of the blood flow to the interior of the arterial chamber as well as stopping blood flow during the arterial systole. The fixation of the venous wall to the deep chamber of the serous pericardium, contributes to growth in resistance during the elevation of venous pressure, making possible the preservation of integrity of the superior venae cavae. The expansion of fasciculi of nodal fibers in the right wall of the superior venae cavae permits that the unlocked impulse in the S-A node also reaches the vascular wall contributing to the shortening and diminution in caliber of the vein.

Dietary restriction and fibre supplementation: Oxidative stress and metabolic shifting for cardiac health

Dietary modification ought to be the first line of strategy in prevention of the development of cardiac disease. The purpose of this study was to investigate whether dietary restriction, dietary-fibre-enriched diet, and their interactions might affect antioxidant capacity and oxidative stress in cardiac tissue. Male Wistar rats (180-200 g; n = 10) were divided into four groups: control ad libitum diet (C), 50% restricted diet (DR), fed with fibre-enriched diet (F), and 50% restricted fibre-enriched diet (DR-F). After 35 days of the treatments, F, DR, and DR-F rats showed low cholesterol, LDL-cholesterol, and triacylglycerol, and high HDL-cholesterol in serum. The DR, DR-F, and F groups had decreased myocardial lipoperoxide and lipid hydroperoxide. The DR-F and F treatments increased superoxide dismutase and glutatione peroxidase (GSH-Px). The DR treatment increased GSH-Px and catalase activities. Dietary fibre beneficial effects were related to metabolic alterations. The F and DR-F groups showed high cardiac glycogen and low lactate dehydrogenase/citrate synthase ratios, indicating diminished anaerobic and elevated aerobic myocardial metabolism in these animals. There was no synergistic effect between dietary restriction and dietary fibre addition, since no differences were observed in markers of oxidative stress in the F and DR-F groups. Dietary fibre supplementation, rather than energy intake and dietary restriction, appears to be the main process retarding oxidative stress in cardiac tissue.

Synergistic action of olive oil supplementation and dietary restriction on serum lipids and cardiac antioxidant defences

Caloric intake is higher than recommended in many populations. Therefore, enhancing olive oil intake alone may not be the most effective way to prevent cardiovascular diseases. The purpose of the present study was to analyse the association of olive oil and dietary restriction on lipid profile and myocardial antioxidant defences. Male Wistar rats (180-200 g, n = 6) were divided into 4 groups: control ad libitum diet (C), 50% restricted diet (DR), fed ad libitum and supplemented with olive oil (3 mL/(kg-day)) (OO), and 50% restricted diet and supplemented with olive oil (DROO). After 30 days of treatments, OO, DR, and DROO groups had increased total cholesterol and high-density lipoprotein cholesterol concentrations. DR and DROO animals showed decreased low-density lipoprotein cholesterol. DROO had the lowest low-density lipoprotein cholesterol concentration. Total lipids and triacylglycerols were raised by dietary restriction and diminished by olive oil. OO rats had higher myocardial Superoxide dismutase and lower catalase and glutathione peroxidase activities than C rats. DR and DROO showed enhanced cardiac Superoxide dismutase, catalase, and glutathione peroxidase activities from the control. Olive oil supplementation alone improved the lipid profile but was more effective when coupled with dietary restriction. There was a synergistic beneficial action of dietary restriction and olive oil on serum lipids and myocardial antioxidant defences.

β-carotene attenuates the paradoxical effect of tobacco smoke on the mortality of rats after experimental myocardial infarction

The objective of this study was to investigate the effects of exposure to tobacco smoke (ETS) in rats that were or were not supplemented with dietary β-carotene (BC), on ventricular remodeling and survival after myocardial infarction (Ml). Rats (n = 189) were allocated to 4 groups: the control group, n = 45; group BC administered 500 mg/kg diet, n = 49, BC supplemented rats; group ETS, n - 55, rats exposed to tobacco smoke; and group BC+ETS, n = 40. Wistar rats weighing 10O g were administered one of the treatments until they weighed 200 to 250 g (∼5 wk). The ETS rats were exposed to cigarette smoke for 30 min 4 times/d, in a chamber connected to a smoking device. After reaching a weight of 200-250 g, rats were subjected to experimental MI (coronary artery occlusion) and mortality rates were determined over the next 105 d. In addition, echocardiographic, isolated heart, morphometrical, and biochemical studies were performed. Mortality data were tested using Kaplan-Meyer curves and other data by 2-way ANOVA. Survival rates were greater in the ETS group (58.2%) than in the control (33.3%) (P = 0.001) and BC+ETS rats (30.0%) (P = 0.007). The groups did not differ in the other comparisons. Left ventricular end-diastolic diameter normalized to body weight was greater and maximal systolic pressures were lower in the ETS groups than in non-ETS groups. Previous exposure to tobacco smoke induced a process of cardiac remodeling after MI. There is a paradoxical protector effect with tobacco smoke exposure, characterized by lower mortality, which is offset by BC supplementation. © 2005 American Society for Nutritional Sciences.

β-Carotene supplementation results in adverse ventricular remodeling after acute myocardial infarction

Objective: We studied the effects of β-carotene (BC) on ventricular remodeling after myocardial infarction. Methods: Myocardial infarction was induced in Wistar rats that were then treated with a BC diet (500 mg/kg of diet per day; MI-BC; n = 27) or a regular diet (MI; n = 27). Hearts were analyzed in vivo and in vitro after 6 mo. Results: BC caused decreased left ventricular wall thickness (MI = 1.49 ± 0.3 mm, MI-BC = 1.23 ± 0.2 mm, P = 0.027) and increased diastolic (MI = 0.83 ± 0.15 cm2, MI-BC = 0.98 ± 0.14 cm2, P = 0.020) and systolic (MI = 0.56 ± 0.12 cm2, MI-BC = 0.75 ± 0.13 cm2, P = 0.002) left ventricular chamber areas. With respect to systolic function, the BC group presented less change in fractional area than did controls (MI = 32.35 ± 6.67, MI-BC = 23.77 ± 6.06, P = 0.004). There was no difference in transmitral diastolic flow velocities between groups. In vitro results showed decreased maximal isovolumetric systolic pressure (MI = 125.5 ± 24.1 mmHg, MI-BC = 95.2 ± 28.4 mmHg, P = 0.019) and increased interstitial myocardial collagen concentration (MI = 3.3 ± 1.2%, MI-BC = 5.8 ± 1.7%, P = 0.004) in BC-treated animals. Infarct sizes were similar between groups (MI = 45.0 ± 6.6%, MI-BC = 48.0 ± 5.8%, P = 0.246). Conclusion: Taken together, these data suggest that BC has adverse effects on ventricular remodeling after myocardial infarction. © 2006 Elsevier Inc. All rights reserved.

Effects of olive oil and its minor constituents on serum lipids, oxidative stress, and energy metabolism in cardiac muscle

Recent lines of evidence suggest that the beneficial effects of olive oil are not only related to its high content of oleic acid, but also to the antioxidant potential of its polyphenols. The aim of this work was determine the effects of olive oil and its components, oleic acid and the polyphenol dihydroxyphenylethanol (DPE), on serum lipids, oxidative stress, and energy metabolism on cardiac tissue. Twenty four male Wistar rats, 200 g, were divided into the following 4 groups (n = 6): control (C), OO group that received extra-virgin olive oil (7.5 mL/kg), OA group was treated with oleic acid (3.45 mL/kg), and the DPE group that received the polyphenol DPE (7.5 mg/kg). These components were administered by gavage over 30 days, twice a week. All animals were provided with food and water ad libitum The results show that olive oil was more effective than its isolated components in improving lipid profile, elevating high-density lipoprotein, and diminishing low-density lipoprotein cholesterol concentrations. Olive oil induced decreased antioxidant Mn-superoxide dismutase activity and diminished protein carbonyl concentration, indicating that olive oil may exert direct antioxidant effect on myocardium. DPE, considered as potential antioxidant, induced elevated aerobic metabolism, triacylglycerols, and lipid hydroperoxides concentrations in cardiac muscle, indicating that long-term intake of this polyphenol may induce its undesirable pro-oxidant activity on myocardium. © 2006 NRC Canada.

DNA damage and nitric oxide synthesis in experimentally infected Balb/c mice with Trypanosoma cruzi

This study aimed to evaluate whether experimental Chagas disease in acute phase under benznidazole therapy can cause DNA damage in peripheral blood, liver, heart, and spleen cells or induce nitric oxide synthesis in spleen cells. Twenty Balb/c mice were distributed into four groups: control (non-infected animals); Trypanosoma cruzi infected; T. cruzi infected and submitted to benznidazole therapy; and only treated with benznidazole. The results obtained with the single cell gel (comet) assay showed that T. cruzi was able induce DNA damage in heart cells of both benznidazole treated or untreated infected mice. Similarly, T. cruzi infected animals showed an increase of DNA lesions in spleen cells. Regarding nitric oxide synthesis, statistically significant differences (p < 0.05) were observed in all experimental groups compared to negative control, the strongest effect observed in the T. cruzi infected group. Taken together, these results indicate that T. cruzi may increase the level of DNA damage in mice heart and spleen cells. Probably, nitric oxide plays an important role in DNA damaging whereas benznidazole was able to minimize induced T. cruzi genotoxic effects in spleen cells. © 2006 Elsevier Inc. All rights reserved.