Studies were carried out to determine the kinetic properties of 5'-nucleotidase from live... more Studies were carried out to determine the kinetic properties of 5'-nucleotidase from liver plasma membranes in rats of different ages; four groups were examined, namely rats 25 +/- 2, 60 +/- 5, 230 +/- 15 and 525 +/- 20 days old. The 5'-nucleotidase showed minimum Vmax values in young rats; differences in this kinetic parameter were not detected among the other groups. However, the Km values increased during growth and development, declined in young animals and increased again in the middle-aged. Arrhenius plots of the 5'-nucleotidase activity showed a single break at aroung 22 degrees C in developing the middle-aged animals; the break temperature decreased to 17 degrees C in the rats 230 +/- 15 days old. The pH-Vmax and pH-Km curves showed a maximum at pH 7.6 at all ages. Lipid analysis of membrane preparations was carried out. Phospholipid composition did not change markedly with age. The cholesterol level decreased between 25 +/- 2 and 60 +/- 5 days. The degree of saturation of fatty acids seemed to increase in the same period, but reached the lowest value in the young rats. The results indicate that either sphingomyelin or other phospholipids do not affect the isothermal kinetics of 5'-nucleotidase during development and aging. Furthermore, phospholipid polar groups as well as the cholesterol and fatty acids of the bulk lipid phase modulate the membrane fluidity in the same way at different ages. Finally, the modifications of the Km with age cannot be correlated with changes in the surface charge.
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 1996
Dietary polyunsaturated fatty acids (PUFA) of the n-3 series that have beneficial effects on mamm... more Dietary polyunsaturated fatty acids (PUFA) of the n-3 series that have beneficial effects on mammalian heart function are typically found at high levels in fish tissues. The effects of dietary fatty acid composition on cardiac function were investigated in the sturgeon. When compared with sturgeon maintained for 1 yr on a diet enriched with saturated fatty acids (SFA) (the coconut oil-supplemented diet, COD), sturgeon maintained on a diet enriched with n-3 PUFA (the fish oil-supplemented diet, FOD) had higher myocardial 20:5(n-3) and lower 20:4(n-6) content with a consequent decrease in the n-6-to-n-3 ratio (from 0.86 to 0.25) and a lower intrinsic in vitro heart rate (22.0 +/- 1.5 vs. 29.9 +/- 1.0 beats/min) and cardiac power output (PO) (0.33 +/- 0.08 vs. 0.48 +/- 0.03 mW/g), but had a greater in vitro scope for cardiac work (almost twice the maximal-to-basal PO ratio). Reducing the oxygen supply to the hearts significantly decreased, by approximately 40%, the maximal in vitro PO ...
Teleosts are a highly diverse group of animals occupying all kind of aquatic environment. Data on... more Teleosts are a highly diverse group of animals occupying all kind of aquatic environment. Data on routine mass specific metabolic rate were re-examined correcting them for the Boltzmann's factor. Teleostean fish were grouped in five broad groups, corresponding to major environmental classifications: polar, temperate, sub-tropical, tropical and deep-water. The specific routine metabolic rate, temperature-corrected using the Boltzmann's factor (MR), and the average base composition of genomes (GC%) were calculated in each group. Fish of the polar habitat showed the highest MR. Temperate fish displayed a significantly higher MR than tropical fish, which had the lowest average value. These results were apparently in agreement with the cold adaptation hypothesis. In contrast with this hypothesis, however, the MR of fish living in deep-water environment turned out to be not significantly different from that of fish living in tropical habitats. Most probably, the amount of oxygen dissolved in the water directly affects MR adaptation. Regarding the different habitats, the genomic GC levels showed a decreasing trend similar to that of MR. Indeed, both polar and temperate fish showed a GC level significantly higher than that of both sub-tropical and tropical fish. Plotting the genomic GC levels versus the MR a significant positive correlation was found, supporting the hypothesis that metabolic rate can explain not only the compositional transition mode (e.g. amphibian/mammals), but also the compositional shifting mode (e.g. fish/fish) of evolution observed for vertebrate genomes.
The ventricular wall of the systemic heart of Octopus vulgaris consists of longitudinal and circu... more The ventricular wall of the systemic heart of Octopus vulgaris consists of longitudinal and circular layers of myocardial cells arranged in an alternate pattern. The use of the corrosion-cast method and scanning electron microscopy has shown that the ventricular wall is supplied through a very rich capillary network, from which a classic venular and venous system originates to ensure drainage. Evidence exists of direct communications between the capillary network and the ventricular lumen. The flow through the coronary system is driven by the ventricularpressure generated during systole. The oxygen extracted from the coronary output accounts for 80%-100% of the total consumption of the heart. In vitro, the coronary output is functionally related to the cardiac output and is highly dependent on the oxygen content of theperfusate, being lower at the highest oxygen levels. The in vitro coronary flow is affected by many humoral factors.
Brazilian Journal of Medical and Biological Research
The Channichthyidae or "icefish" represent an intriguing example of extreme adaptation ... more The Channichthyidae or "icefish" represent an intriguing example of extreme adaptation to the stable low temperature and high oxygen content of the Antarctic waters. The lack of respiratory pigments (hemoglobin and myoglobin) in these teleosts is associated with relatively low oxygen consumption and relevant cardio-circulatory adjustments which include large blood volume, increased relative heart weight (cardiomegaly), and very high cardiac output. The heart has the ability to displace large systolic volumes at a low rate and relatively low pressure, with large ventricular fillings (high ventricular compliance), whereas it is incapable of facing increased afterloads. These functional aspects of mechanical flexibility and restrictions of the cardiac pump have been tentatively related to some constructional aspects of the icefish cardiomegaly, particularly, at the whole ventricular level, to the trabeculate type of myo-architecture, and, at the subcellular level, to the conf...
Bollettino della Societa italiana di biologia sperimentale, Feb 15, 1980
The effect of age on the kinetic properties of the plasma membrane 5'-nucleotidase in liver c... more The effect of age on the kinetic properties of the plasma membrane 5'-nucleotidase in liver cells is studied. Vmax and Km and the discontinuity temperature are lower in the 230 +/- 15 days old rats. It appears that lipids do not affect the isotermic kinetic of the enzyme, while the decrease in the discontinuity temperature in the 230 +/- 15 days old animals might be related to the higher percent of insaturated fatty acids.
This paper reviews evidence that the fatty acid composition of dietary lipids influences the resp... more This paper reviews evidence that the fatty acid composition of dietary lipids influences the respiratory and cardiovascular physiology of Adriatic sturgeon (Acipenser naccarii) and, thereby, their tolerance of the stress of hypoxia. Sturgeon fed a commercial diet enriched in fish oil (menhaden oil as 15 % of dry feed weight), with an elevated content of highly unsaturated fatty acids of the ω3 series (ω3 HUFA), had a significantly lower standard metabolic rate (SMR) and routine oxygen consumption (Mo 2) than those fed a diet enriched with the same quantity of hydrogenated coconut oil, with an elevated content of saturated fatty acids (SFA). Both groups grew equally well. As a result of this difference in aerobic metabolism, sturgeon fed the ω3 HUFA and SFA responded differently when exposed to hypoxic challenges, those fed ω3 HUFA appearing more hypoxia-tolerant. Sturgeon fed ω3 HUFA exhibited no significant reflex
The effects of exercise on the rates of protein synthesis in the chambers of the trout heart were... more The effects of exercise on the rates of protein synthesis in the chambers of the trout heart were investigated in vitro and in vivo. An in vitro rainbow trout heart preparation was developed which permitted perfusion of the coronary supply to the compact region of the ventricular muscle. This preparation was used to examine the mechanical responses to preload pressures, the oxygen consumption at different power outputs and the rates of protein synthesis in the various heart components. By increasing preload pressure it was possible to double cardiac output, oxygen consumption and power output without changing heart rate. Mechanical efficiency of the hearts was approximately 20%. Perfusion of the coronary vessels improved cardiac output. Protein synthesis was measured in isolated hearts by the incorporation of [3H]phenylalanine added at high concentration (1.35 mmol l-1) to the perfusion medium. The various chambers of the heart showed marked differences in their rates of protein syn...
... 1. Wiley and Sons, Inc. New York, London, Sidney, Toronto, 1971. Lohmann, K. “Uber den Chemis... more ... 1. Wiley and Sons, Inc. New York, London, Sidney, Toronto, 1971. Lohmann, K. “Uber den Chemismus der Muskelkontraktion”. Naturwiss, 22: 409-411, 1934. Lundsgaard, E. “Weitere Untersuchugen über Muskelkontraktionen ohne Milchsäurebildung”. ...
The effect of increasing oxygen supply on the perfused systemic heart of Octopus vulgaris (Lam.) ... more The effect of increasing oxygen supply on the perfused systemic heart of Octopus vulgaris (Lam.) by using oxygenated or haemocyanin-containing perfusates was investigated. Providing aerated blood or seawater solutions of haemocyanin that were comparable with blood in oxygen-carrying capacity improved the performance of the isolated heart compared with that of hearts perfused with aerated sea water. Aortic outputs were similar to in vivo values (44ml min−1 g−1) at close to in vivo values of preload and afterload owing to an increase in both heart rate (from 24.0 to 38.4beatsmin−1) and stroke volume (from 0.69 to 1.10ml g−1). Coronary flow fell in these conditions, becoming 2.5% of the aortic output (against 24% with aerated sea water). A parallel increase in coronary resistance was found. Oxygenated sea water also improved the performance of the heart, mainly by improving the stroke volume. Both with haemocyanin solutions or blood and with oxygenated sea water, the isolated heart was...
A technique is described which allowed the measurement of the oxygen consumption of the isolated ... more A technique is described which allowed the measurement of the oxygen consumption of the isolated heart of Octopus vulgaris. Contraction of the heart resulted in an aortic output and a flow through the heart muscle into coronary veins (the coronary output). The flow and oxygen content of the aortic output and the coronary output were measured with variable input pressures and constant output back pressure (volume loaded), variable output back pressure and constant aortic output (pressure loaded), and during hypoxia. Volume loading of the heart resulted in an increase in aortic output, power output and total oxygen consumption. Pressure loading increased power output and total oxygen consumption of the heart. Exposure to hypoxia decreased the aortic output, power output and total cardiac oxygen consumption. In the response of the heart to reduced work, brought about either by a reduced input pressure or by hypoxic perfusate, the power output was linearly related to the total oxygen co...
Bollettino della Società italiana di biologia sperimentale, Jan 30, 1978
The influence of age on the isothermic and temperature-induced kinetics of the plasma membrane 5&... more The influence of age on the isothermic and temperature-induced kinetics of the plasma membrane 5'-nucleotidase was studied in rat liver. The apparent Km values increased with age, while the Vmax, the temperature discontinuity and the Ex above and below the max break were unaffected.
Studies were carried out to determine the kinetic properties of 5'-nucleotidase from live... more Studies were carried out to determine the kinetic properties of 5'-nucleotidase from liver plasma membranes in rats of different ages; four groups were examined, namely rats 25 +/- 2, 60 +/- 5, 230 +/- 15 and 525 +/- 20 days old. The 5'-nucleotidase showed minimum Vmax values in young rats; differences in this kinetic parameter were not detected among the other groups. However, the Km values increased during growth and development, declined in young animals and increased again in the middle-aged. Arrhenius plots of the 5'-nucleotidase activity showed a single break at aroung 22 degrees C in developing the middle-aged animals; the break temperature decreased to 17 degrees C in the rats 230 +/- 15 days old. The pH-Vmax and pH-Km curves showed a maximum at pH 7.6 at all ages. Lipid analysis of membrane preparations was carried out. Phospholipid composition did not change markedly with age. The cholesterol level decreased between 25 +/- 2 and 60 +/- 5 days. The degree of saturation of fatty acids seemed to increase in the same period, but reached the lowest value in the young rats. The results indicate that either sphingomyelin or other phospholipids do not affect the isothermal kinetics of 5'-nucleotidase during development and aging. Furthermore, phospholipid polar groups as well as the cholesterol and fatty acids of the bulk lipid phase modulate the membrane fluidity in the same way at different ages. Finally, the modifications of the Km with age cannot be correlated with changes in the surface charge.
American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 1996
Dietary polyunsaturated fatty acids (PUFA) of the n-3 series that have beneficial effects on mamm... more Dietary polyunsaturated fatty acids (PUFA) of the n-3 series that have beneficial effects on mammalian heart function are typically found at high levels in fish tissues. The effects of dietary fatty acid composition on cardiac function were investigated in the sturgeon. When compared with sturgeon maintained for 1 yr on a diet enriched with saturated fatty acids (SFA) (the coconut oil-supplemented diet, COD), sturgeon maintained on a diet enriched with n-3 PUFA (the fish oil-supplemented diet, FOD) had higher myocardial 20:5(n-3) and lower 20:4(n-6) content with a consequent decrease in the n-6-to-n-3 ratio (from 0.86 to 0.25) and a lower intrinsic in vitro heart rate (22.0 +/- 1.5 vs. 29.9 +/- 1.0 beats/min) and cardiac power output (PO) (0.33 +/- 0.08 vs. 0.48 +/- 0.03 mW/g), but had a greater in vitro scope for cardiac work (almost twice the maximal-to-basal PO ratio). Reducing the oxygen supply to the hearts significantly decreased, by approximately 40%, the maximal in vitro PO ...
Teleosts are a highly diverse group of animals occupying all kind of aquatic environment. Data on... more Teleosts are a highly diverse group of animals occupying all kind of aquatic environment. Data on routine mass specific metabolic rate were re-examined correcting them for the Boltzmann's factor. Teleostean fish were grouped in five broad groups, corresponding to major environmental classifications: polar, temperate, sub-tropical, tropical and deep-water. The specific routine metabolic rate, temperature-corrected using the Boltzmann's factor (MR), and the average base composition of genomes (GC%) were calculated in each group. Fish of the polar habitat showed the highest MR. Temperate fish displayed a significantly higher MR than tropical fish, which had the lowest average value. These results were apparently in agreement with the cold adaptation hypothesis. In contrast with this hypothesis, however, the MR of fish living in deep-water environment turned out to be not significantly different from that of fish living in tropical habitats. Most probably, the amount of oxygen dissolved in the water directly affects MR adaptation. Regarding the different habitats, the genomic GC levels showed a decreasing trend similar to that of MR. Indeed, both polar and temperate fish showed a GC level significantly higher than that of both sub-tropical and tropical fish. Plotting the genomic GC levels versus the MR a significant positive correlation was found, supporting the hypothesis that metabolic rate can explain not only the compositional transition mode (e.g. amphibian/mammals), but also the compositional shifting mode (e.g. fish/fish) of evolution observed for vertebrate genomes.
The ventricular wall of the systemic heart of Octopus vulgaris consists of longitudinal and circu... more The ventricular wall of the systemic heart of Octopus vulgaris consists of longitudinal and circular layers of myocardial cells arranged in an alternate pattern. The use of the corrosion-cast method and scanning electron microscopy has shown that the ventricular wall is supplied through a very rich capillary network, from which a classic venular and venous system originates to ensure drainage. Evidence exists of direct communications between the capillary network and the ventricular lumen. The flow through the coronary system is driven by the ventricularpressure generated during systole. The oxygen extracted from the coronary output accounts for 80%-100% of the total consumption of the heart. In vitro, the coronary output is functionally related to the cardiac output and is highly dependent on the oxygen content of theperfusate, being lower at the highest oxygen levels. The in vitro coronary flow is affected by many humoral factors.
Brazilian Journal of Medical and Biological Research
The Channichthyidae or "icefish" represent an intriguing example of extreme adaptation ... more The Channichthyidae or "icefish" represent an intriguing example of extreme adaptation to the stable low temperature and high oxygen content of the Antarctic waters. The lack of respiratory pigments (hemoglobin and myoglobin) in these teleosts is associated with relatively low oxygen consumption and relevant cardio-circulatory adjustments which include large blood volume, increased relative heart weight (cardiomegaly), and very high cardiac output. The heart has the ability to displace large systolic volumes at a low rate and relatively low pressure, with large ventricular fillings (high ventricular compliance), whereas it is incapable of facing increased afterloads. These functional aspects of mechanical flexibility and restrictions of the cardiac pump have been tentatively related to some constructional aspects of the icefish cardiomegaly, particularly, at the whole ventricular level, to the trabeculate type of myo-architecture, and, at the subcellular level, to the conf...
Bollettino della Societa italiana di biologia sperimentale, Feb 15, 1980
The effect of age on the kinetic properties of the plasma membrane 5'-nucleotidase in liver c... more The effect of age on the kinetic properties of the plasma membrane 5'-nucleotidase in liver cells is studied. Vmax and Km and the discontinuity temperature are lower in the 230 +/- 15 days old rats. It appears that lipids do not affect the isotermic kinetic of the enzyme, while the decrease in the discontinuity temperature in the 230 +/- 15 days old animals might be related to the higher percent of insaturated fatty acids.
This paper reviews evidence that the fatty acid composition of dietary lipids influences the resp... more This paper reviews evidence that the fatty acid composition of dietary lipids influences the respiratory and cardiovascular physiology of Adriatic sturgeon (Acipenser naccarii) and, thereby, their tolerance of the stress of hypoxia. Sturgeon fed a commercial diet enriched in fish oil (menhaden oil as 15 % of dry feed weight), with an elevated content of highly unsaturated fatty acids of the ω3 series (ω3 HUFA), had a significantly lower standard metabolic rate (SMR) and routine oxygen consumption (Mo 2) than those fed a diet enriched with the same quantity of hydrogenated coconut oil, with an elevated content of saturated fatty acids (SFA). Both groups grew equally well. As a result of this difference in aerobic metabolism, sturgeon fed the ω3 HUFA and SFA responded differently when exposed to hypoxic challenges, those fed ω3 HUFA appearing more hypoxia-tolerant. Sturgeon fed ω3 HUFA exhibited no significant reflex
The effects of exercise on the rates of protein synthesis in the chambers of the trout heart were... more The effects of exercise on the rates of protein synthesis in the chambers of the trout heart were investigated in vitro and in vivo. An in vitro rainbow trout heart preparation was developed which permitted perfusion of the coronary supply to the compact region of the ventricular muscle. This preparation was used to examine the mechanical responses to preload pressures, the oxygen consumption at different power outputs and the rates of protein synthesis in the various heart components. By increasing preload pressure it was possible to double cardiac output, oxygen consumption and power output without changing heart rate. Mechanical efficiency of the hearts was approximately 20%. Perfusion of the coronary vessels improved cardiac output. Protein synthesis was measured in isolated hearts by the incorporation of [3H]phenylalanine added at high concentration (1.35 mmol l-1) to the perfusion medium. The various chambers of the heart showed marked differences in their rates of protein syn...
... 1. Wiley and Sons, Inc. New York, London, Sidney, Toronto, 1971. Lohmann, K. “Uber den Chemis... more ... 1. Wiley and Sons, Inc. New York, London, Sidney, Toronto, 1971. Lohmann, K. “Uber den Chemismus der Muskelkontraktion”. Naturwiss, 22: 409-411, 1934. Lundsgaard, E. “Weitere Untersuchugen über Muskelkontraktionen ohne Milchsäurebildung”. ...
The effect of increasing oxygen supply on the perfused systemic heart of Octopus vulgaris (Lam.) ... more The effect of increasing oxygen supply on the perfused systemic heart of Octopus vulgaris (Lam.) by using oxygenated or haemocyanin-containing perfusates was investigated. Providing aerated blood or seawater solutions of haemocyanin that were comparable with blood in oxygen-carrying capacity improved the performance of the isolated heart compared with that of hearts perfused with aerated sea water. Aortic outputs were similar to in vivo values (44ml min−1 g−1) at close to in vivo values of preload and afterload owing to an increase in both heart rate (from 24.0 to 38.4beatsmin−1) and stroke volume (from 0.69 to 1.10ml g−1). Coronary flow fell in these conditions, becoming 2.5% of the aortic output (against 24% with aerated sea water). A parallel increase in coronary resistance was found. Oxygenated sea water also improved the performance of the heart, mainly by improving the stroke volume. Both with haemocyanin solutions or blood and with oxygenated sea water, the isolated heart was...
A technique is described which allowed the measurement of the oxygen consumption of the isolated ... more A technique is described which allowed the measurement of the oxygen consumption of the isolated heart of Octopus vulgaris. Contraction of the heart resulted in an aortic output and a flow through the heart muscle into coronary veins (the coronary output). The flow and oxygen content of the aortic output and the coronary output were measured with variable input pressures and constant output back pressure (volume loaded), variable output back pressure and constant aortic output (pressure loaded), and during hypoxia. Volume loading of the heart resulted in an increase in aortic output, power output and total oxygen consumption. Pressure loading increased power output and total oxygen consumption of the heart. Exposure to hypoxia decreased the aortic output, power output and total cardiac oxygen consumption. In the response of the heart to reduced work, brought about either by a reduced input pressure or by hypoxic perfusate, the power output was linearly related to the total oxygen co...
Bollettino della Società italiana di biologia sperimentale, Jan 30, 1978
The influence of age on the isothermic and temperature-induced kinetics of the plasma membrane 5&... more The influence of age on the isothermic and temperature-induced kinetics of the plasma membrane 5'-nucleotidase was studied in rat liver. The apparent Km values increased with age, while the Vmax, the temperature discontinuity and the Ex above and below the max break were unaffected.
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