Hearts from rats aged 3 months and 24 months respectively were isolated and subjected to a brief ... more Hearts from rats aged 3 months and 24 months respectively were isolated and subjected to a brief ischemia. The extent of myocardial injury, measured by release of creatine phosphokinase into coronary effluents and by developed tension, was greater in the young rats than in the old when compared with their corresponding non-ischemic controls. The amount of peroxidation, measured in the isolated mitochondria using the malondialdehyde method, was also greater in the younger rats. In contrast, when mitochondria from non-ischemic hearts were incubated for 20 minutes in a medium containing FeCl3, NADPH and ADP, known to generate hydroxyl radicals, significant peroxidation (together with a decrease in respiratory control indices) was obtained only from mitochondria isolated from the older rats. If, as the in vitro results suggest, the mitochondria of the old rats are not less sensitive to peroxidative attack, the difference between the effects of ischemia in the two age groups may be due t...
The majority of reports concerning the performance of senescent heart in both human and animal mo... more The majority of reports concerning the performance of senescent heart in both human and animal models states that, at rest, most hemodynamic parameters are substantially unchanged during aging, with the exception of a prolongation of left ventricular ejection time and a decrease in the early diastolic filling rate. A biochemical rationale for the increased early diastolic filling time with age seems to be the enhanced stiffness of left ventricular wall due to either myocardial hypertrophy or collagen tissue accumulation. The prolonged time of contraction and the inadequate response to stress of cardiac muscle in elderly subjects may be the consequence of changes in different steps of the excitation-contraction coupling, namely altered intracellular calcium homeostasis, reduced availability of highly energetic compounds, and impaired response to adrenergic stimulation. These defects can cause major hemodynamic changes when the heart is subjected to volume or pressure overload. In fac...
Recent advances in studies on cardiac structure and metabolism, 1975
A close relationship has been observed between polyamine, as spermine and spermidine, and nucleic... more A close relationship has been observed between polyamine, as spermine and spermidine, and nucleic acid synthesis during heart hypertrophy, induced in the rats experimentally, by physical exericse (swimming). The role of spermine on RNA synthesis has been studied by perfusion experiments of the heart. Spermine is able to stimulate myocardial RNA synthesis of all subcellular fractions. The biochemical mechanism of this phenomenon may be explained by the results of histone acetylation under the action of spermine, showing an increased radioactivity of F 2aI and F 2a2 arginine-rich histone fractions. This suggests that spermine may act modulating histone acetylation, with a consequence on the gene transcription mechanism.
Italian heart journal. Supplement : official journal of the Italian Federation of Cardiology, 2003
The ventricular remodeling following an acute myocardial infarction generates a non-contractile f... more The ventricular remodeling following an acute myocardial infarction generates a non-contractile fibrous scare which might provoke cardiac failure. Several techniques aimed at recovering myocardial performance through the utilization of stem cells have been investigated in these last years. Embryonal stem cells, although they are characterized by an elevated differentiation potential, present technical and ethical concerns. Thus, most studies have been addressed towards adult (somatic) stem cells. Three categories of adult stem cells are now mainly investigated: a) satellite cells from skeletal muscle, b) mesenchymal stem cells from bone marrow, c) stem cells which are eventually present in the cardiac tissue. Skeletal myoblasts, even if they are not able to differentiate in cardiomyocytes, can improve cardiac contractility at the level of the fibrous scare which substitutes the necrotic area. It is also possible to isolate stem cells from bone marrow which can originate several cell...
In quiescent thymocytes, mitochondrial de-energization was not correlated to apoptotic death. In ... more In quiescent thymocytes, mitochondrial de-energization was not correlated to apoptotic death. In fact, thymocytes treated with oligomycin, a highly specific inhibitor of ATP synthase, alone or with atractyloside to block ATP translocation from the cytoplasm, were alive, even if their mitochondria were depolarized, as revealed by flow cytometry after Rhodamine 123 staining. Furthermore, oligomycin was a powerful inhibitor of apoptosis induced in rat thymocytes by dexamethasone and, to a lesser extent, by the calcium ionophore A23187 and etoposide, but was without effect when apoptosis was induced by staurosporine, and increased cell death in mitogen-treated thymocytes. The inhibition of apoptosis was confirmed by morphological criteria, inhibition of inter-nucleosomal DNA fragmentation and inhibition of the loss of membrane integrity. The anti-apoptotic effect of oligomycin in cells treated with A23187 or etoposide was correlated to the inhibition of protein synthesis, while inhibiti...
European journal of emergency medicine : official journal of the European Society for Emergency Medicine, 1997
Plasma activity of myeloperoxidase (MPO), malondialdehyde (MDA) and 4-hydroxynonenal (HNE) was me... more Plasma activity of myeloperoxidase (MPO), malondialdehyde (MDA) and 4-hydroxynonenal (HNE) was measured prior to any treatment in 50 consecutive stroke patients with acute cerebral ischaemia, as well as in 14 healthy control subjects. Mann-Whitney-Wilcoxon test for unpaired data showed greater values of MPO (p < 0.01), MDA (p < 0.01) and HNE (p < 0.05) in stroke patients compared with controls. Considering as covariates the level of consciousness (GCS < 9 vs > or = 9), possible sources of emboli (yes vs no), leukocyte count (< 10 x 10(9)/1 vs > or = 10 x 10(9)/1) and relevant comorbid diseases (yes vs no), exact multiple logistic regression analysis indicated that only the presence of possible cardiac sources of emboli was associated with changes in by-products of lipid peroxidation. If confirmed in a larger series of subjects, our results could have therapeutic implications, providing more support for the use of free radical scavengers in the acute care of stro...
In the myocardial cell, stimulation of the K opioid receptor is involved in the modulation of cyt... more In the myocardial cell, stimulation of the K opioid receptor is involved in the modulation of cytosolic calcium and pH homeostasis, as well as in the regulation of myofilament responsiveness to calcium. In the present study, we found that prodynorphin mRNA, which encodes for the synthesis of a common precursor of opioid peptides interacting with K sites, is synthesized both in atrial and ventricular tissue of the rat heart. In adult cultured rat ventricular cardiomyocytes, the level of prodynorphin mRNA did not differ from that detected in the original ventricular tissue. This finding indicates that the myocardial cell is a source for prodynorphin gene expression and has the potential for an intrinsic synthesis of dynorphin-related peptides.
Mitochondria extracted from the hearts of Wistar rats aged 6 and 24 months showed similar values ... more Mitochondria extracted from the hearts of Wistar rats aged 6 and 24 months showed similar values for the respiratory control index (RCI), state 3 oxygen consumption (QO2) and ADP/O measured using glutamate or succinate as substrates; with the exception that the QO2 of the aged rats was lower than that of the young rats in the presence of glutamate. The consumption of O2 induced by 2-oxoglutarate and ADP was similar in both age groups. Concentrations of external free Ca2+ ranging from 0.2 to 0.8 microM produced an increase in O2 consumption and ATP formation in the young mitochondria, with a maximum effect at 0.2 microM external free Ca2+. Little or no change in O2 consumption and ATP formation was evident in aged mitochondria following incubations in concentrations of external free Ca2+ ranging from 0.2 to 0.8 microM. The continuous rate of formation of ATP, measured in the presence of 0.2 microM external free Ca2+ using a luminescence method, confirmed the previous results. This st...
Research communications in chemical pathology and pharmacology, 1993
The GSH level in myocardial tissue represents an important defense mechanism against oxygen toxic... more The GSH level in myocardial tissue represents an important defense mechanism against oxygen toxicity. Since the ischemia-induced depletion of GSH might favour the cytotoxicity of oxygen-derived free radicals produced during reperfusion, we assessed the effects of the GSH donor, glutathione monoethylester, in anaesthetized pigs subjected to 90 minutes of coronary occlusion followed by 30 minutes reperfusion. The drug was infused intracoronarily at a dose of 1 mg/ml (0.5 ml/min) throughout the experimental period. After coronary occlusion and reperfusion, we found a decrease in GSH, ADP, ATP and phosphocreatine levels in reperfused compared with non-ischemic tissue. Less evident were the differences in mitochondrial function, there being only a reduction in the reperfused tissue of the respiratory control index and state 3 respiration values when pyruvate was used as substrate. The infusion with glutathione monoethylester decreased the depletion of tissue GSH and improved the GSH/GSSG...
The expression of the prodynorphin gene was investigated in adult cultured rat ventricular cardia... more The expression of the prodynorphin gene was investigated in adult cultured rat ventricular cardiac myocytes by using a sensitive solution hybridization RNase protection assay for the quantitative analysis of prodynorphin mRNA. Myocyte culture in high KCl resulted, after 4 h, in a marked increase in cellular prodynorphin mRNA, while a KCl treatment for 6, 12, or 24 h progressively down-regulated the levels of prodynorphin mRNA below the control value. Immunoreactive dynorphin B, a biologically active end product of the precursor, was found to be present in the culture medium in significantly higher amounts than in the cardiac myocytes. The levels of this biologically active K opioid receptor agonist significantly increased after 4 h of KCl treatment and were markedly reduced following a 24-h exposure of the cardiac myocytes to KCl. These KCl-induced effects were all abolished by cell incubation in the presence of the calcium channel blocker verapamil. In single cardiac myocytes, acut...
In mitochondria from alpha-tocopherol-deficient rabbit hearts (30 days), there was a close correl... more In mitochondria from alpha-tocopherol-deficient rabbit hearts (30 days), there was a close correlation between the decline in respiration and the incidence of membrane peroxidation. In the same mitochondria, an increased formation of oxygen radicals was also observed, whereas superoxide dismutase activity was only slightly depressed. The exposure of mitochondria to exogeneous oxygen radicals generated by a xanthine-xanthine oxidase system caused a marked decrease in their oxidative phosphorylation capacity associated with an increase in lipid peroxidation breakdown. This was particularly evident in mitochondria from alpha-tocopherol-deficient rabbits. In mitochondria from deficient animals that had been rehabilitated with alpha-tocopherol, the toxic effect of oxygen radicals was less evident.
International journal for vitamin and nutrition research. Internationale Zeitschrift für Vitamin- und Ernährungsforschung. Journal international de vitaminologie et de nutrition, 1982
The mitochondria extracted from hearts of alpha-tocopherol deficient rabbits showed a decreased m... more The mitochondria extracted from hearts of alpha-tocopherol deficient rabbits showed a decreased mitochondrial function and an increased formation of oxygen radicals associated with a decreased superoxide dismutase activity. The exposure of the alpha-tocopherol deficient mitochondria to exogeneous oxygen radicals caused a marked decrease in the mitochondrial function with respect to control mitochondria, which was partially reversed by the addition in vitro of alpha-tocopherol.
Ornithine decarboxylase activity evaluated during the perfusion of isolated rat hearts by a metho... more Ornithine decarboxylase activity evaluated during the perfusion of isolated rat hearts by a method 'in situ' was rapidly increased when the hearts were infused with isoprenaline (isoproterenol). Omission of Ca2+ from the perfusion medium or the administration of verapamil to the perfused hearts decreased the isoprenaline-stimulated ornithine decarboxylase activity, whereas a marked stimulatory effect was registered when the hearts were perfused with the Ca2+ ionophore A23187.
3H-tocopherol was administered by perfusion to rabbit hearts and rapidly entered the myocardial c... more 3H-tocopherol was administered by perfusion to rabbit hearts and rapidly entered the myocardial cells with an incorporation rate which was more evident inthe alpha-tocopherol deficient hearts than in the control hearts. During perfusion, the labelled alpha-tocopherol was slightly metabolized and 85% of the radioactivity was recovered as authentic alpha-tocopherol. The pattern of alpha-tocopherol distribution showed in both perfused hearts a significant binding of the radioactivity to the nuclei. The vitamin was also retained with high specific labelling in the mitochondria and in a lower degree in the microsomes and soluble fractions. Small amounts of radioactivity was found bound to the myofibrils. The study of the intranuclear distribution of tocopherol has revealed that the tocopherol-binding species were acidic nuclear macromolecules which exhibited characteristics of non-histone chromosomal proteins. Administration of alpha-tocopherol exhibited a positive effect on the stimulat...
Removal of dithiothreitol (DTT) from partially purified ornithine decarboxylase (ODC) led to an a... more Removal of dithiothreitol (DTT) from partially purified ornithine decarboxylase (ODC) led to an almost complete inhibition of enzymic activity. The inactivation was reversed by addition of millimolar concentrations of DTT, whereas natural reductants such as NADPH or NADH were ineffective, and GSH had only a limited effect. Addition of rat liver cytosol to the incubation mixture resulted in a noticeable re-activation of ODC; however, dialysed cytosol had little effect unless NADPH or GSH was present. Fractionation of rat liver cytosol by gel filtration on Sephadex G-75 yielded two fractions involved in the NADPH- and GSH-dependent re-activation of ODC: one designated 'A', eluted near the void volume (Mr greater than or equal to 60,000), and the other designated 'B', eluted later (Mr approx. 12,000). The NADPH-dependent mechanism required both fractions A and B for maximal ODC re-activation; the most effective concentration of NADPH was 0.15 mM, although a significant ...
Heart ornithine decarboxylase (ODC) from isoproterenol treated rats was compared to heart ODC fro... more Heart ornithine decarboxylase (ODC) from isoproterenol treated rats was compared to heart ODC from control rats. Isoproterenol administration did not significantly change Km for ornithine, but it induced a marked increase of Vmax, X Km for pyridoxal phosphate (PLP) was somewhat reduced. Both Kornm and Vmax were a function of the dithiothreitol (DTT) concentration, in a similar way for control and stimulated enzyme. Two ODC forms were detected by ion exchange chromatography in both control and isoproterenol treated hearts. In control heart, ODC specific activity was high in cytosol and nucleoli. Isoproterenol administration induced a remarkable increase of the cytosolic enzyme only.
Cyanide-resistant respiration in heart homogenates supplemented with 1 mM NADH was greater in hyp... more Cyanide-resistant respiration in heart homogenates supplemented with 1 mM NADH was greater in hypertrophied homogenates (60 days banding) with respect to control homogenates, particularly when the homogenates were incubated in 100% oxygen. The intermyofibrillar mitochondria from hypertrophied hearts produced more superoxide radicals than sub-sarcolemmal mitochondria, and both values were greater than in the unbanded group. H2O2 formation was more evident in the intact mitochondria prepared from hypertrophied hearts than in those of the control hearts. Moreover, the perfusion of isolated hearts in anoxic and reoxygenated conditions caused a greater lipoperoxidative and functional damage at the mitochondrial level in hypertrophied hearts than in the control hearts. These results, correlate with the reduction in mitochondrial function found in the overloaded hearts, suggest an involvement of the reactive species of oxygen in the formation of cardiac damage induced by prolonged aortic b...
Research communications in chemical pathology and pharmacology, 1989
Trimetazidine at concentrations above 100 microM competed with cytochrome c in scavenging O2.- ra... more Trimetazidine at concentrations above 100 microM competed with cytochrome c in scavenging O2.- radicals formed by the reaction catalyzed by the xanthine oxidase enzyme upon xanthine. This scavenger effect was also observed when O2.- were generated by active human neutrophils in which the rate of O2.- formation was monitored by following the reduction of cytochrome c or the emission of luminol-dependent chemiluminescence. An additional scavenger effect of trimetazidine was measured in a OH. chemical generating system whereby the breakdown of deoxyribose by the thiobarbituric acid assay was detected. This study suggests that trimetazidine might function as an antioxy radical compound in conditions of increased oxy radical production.
After ligation of the left coronary artery, porcine cardiac mitochondria were isolated by homogen... more After ligation of the left coronary artery, porcine cardiac mitochondria were isolated by homogenizing the tissue and treating the myofibrillar pellet with nagarse. When compared with unligated controls, the ischemic myocardium showed decreases in phosphocreatine (to 41%), ATP (to 56%) and in the mitochondrial respiratory control index (to 69% and 78% as measured with glutamate and succinate respectively). No changes were found in the corresponding P/O ratios. Similar results were obtained upon separation of the mitochondria into two main fractions by a density gradient technique, though only one of these fractions showed a fall in succinate-supported respiration. The results suggest that ischemia decreases the NADH-dehydrogenase activity of cardiac mitochondria.
Hearts from rats aged 3 months and 24 months respectively were isolated and subjected to a brief ... more Hearts from rats aged 3 months and 24 months respectively were isolated and subjected to a brief ischemia. The extent of myocardial injury, measured by release of creatine phosphokinase into coronary effluents and by developed tension, was greater in the young rats than in the old when compared with their corresponding non-ischemic controls. The amount of peroxidation, measured in the isolated mitochondria using the malondialdehyde method, was also greater in the younger rats. In contrast, when mitochondria from non-ischemic hearts were incubated for 20 minutes in a medium containing FeCl3, NADPH and ADP, known to generate hydroxyl radicals, significant peroxidation (together with a decrease in respiratory control indices) was obtained only from mitochondria isolated from the older rats. If, as the in vitro results suggest, the mitochondria of the old rats are not less sensitive to peroxidative attack, the difference between the effects of ischemia in the two age groups may be due t...
The majority of reports concerning the performance of senescent heart in both human and animal mo... more The majority of reports concerning the performance of senescent heart in both human and animal models states that, at rest, most hemodynamic parameters are substantially unchanged during aging, with the exception of a prolongation of left ventricular ejection time and a decrease in the early diastolic filling rate. A biochemical rationale for the increased early diastolic filling time with age seems to be the enhanced stiffness of left ventricular wall due to either myocardial hypertrophy or collagen tissue accumulation. The prolonged time of contraction and the inadequate response to stress of cardiac muscle in elderly subjects may be the consequence of changes in different steps of the excitation-contraction coupling, namely altered intracellular calcium homeostasis, reduced availability of highly energetic compounds, and impaired response to adrenergic stimulation. These defects can cause major hemodynamic changes when the heart is subjected to volume or pressure overload. In fac...
Recent advances in studies on cardiac structure and metabolism, 1975
A close relationship has been observed between polyamine, as spermine and spermidine, and nucleic... more A close relationship has been observed between polyamine, as spermine and spermidine, and nucleic acid synthesis during heart hypertrophy, induced in the rats experimentally, by physical exericse (swimming). The role of spermine on RNA synthesis has been studied by perfusion experiments of the heart. Spermine is able to stimulate myocardial RNA synthesis of all subcellular fractions. The biochemical mechanism of this phenomenon may be explained by the results of histone acetylation under the action of spermine, showing an increased radioactivity of F 2aI and F 2a2 arginine-rich histone fractions. This suggests that spermine may act modulating histone acetylation, with a consequence on the gene transcription mechanism.
Italian heart journal. Supplement : official journal of the Italian Federation of Cardiology, 2003
The ventricular remodeling following an acute myocardial infarction generates a non-contractile f... more The ventricular remodeling following an acute myocardial infarction generates a non-contractile fibrous scare which might provoke cardiac failure. Several techniques aimed at recovering myocardial performance through the utilization of stem cells have been investigated in these last years. Embryonal stem cells, although they are characterized by an elevated differentiation potential, present technical and ethical concerns. Thus, most studies have been addressed towards adult (somatic) stem cells. Three categories of adult stem cells are now mainly investigated: a) satellite cells from skeletal muscle, b) mesenchymal stem cells from bone marrow, c) stem cells which are eventually present in the cardiac tissue. Skeletal myoblasts, even if they are not able to differentiate in cardiomyocytes, can improve cardiac contractility at the level of the fibrous scare which substitutes the necrotic area. It is also possible to isolate stem cells from bone marrow which can originate several cell...
In quiescent thymocytes, mitochondrial de-energization was not correlated to apoptotic death. In ... more In quiescent thymocytes, mitochondrial de-energization was not correlated to apoptotic death. In fact, thymocytes treated with oligomycin, a highly specific inhibitor of ATP synthase, alone or with atractyloside to block ATP translocation from the cytoplasm, were alive, even if their mitochondria were depolarized, as revealed by flow cytometry after Rhodamine 123 staining. Furthermore, oligomycin was a powerful inhibitor of apoptosis induced in rat thymocytes by dexamethasone and, to a lesser extent, by the calcium ionophore A23187 and etoposide, but was without effect when apoptosis was induced by staurosporine, and increased cell death in mitogen-treated thymocytes. The inhibition of apoptosis was confirmed by morphological criteria, inhibition of inter-nucleosomal DNA fragmentation and inhibition of the loss of membrane integrity. The anti-apoptotic effect of oligomycin in cells treated with A23187 or etoposide was correlated to the inhibition of protein synthesis, while inhibiti...
European journal of emergency medicine : official journal of the European Society for Emergency Medicine, 1997
Plasma activity of myeloperoxidase (MPO), malondialdehyde (MDA) and 4-hydroxynonenal (HNE) was me... more Plasma activity of myeloperoxidase (MPO), malondialdehyde (MDA) and 4-hydroxynonenal (HNE) was measured prior to any treatment in 50 consecutive stroke patients with acute cerebral ischaemia, as well as in 14 healthy control subjects. Mann-Whitney-Wilcoxon test for unpaired data showed greater values of MPO (p < 0.01), MDA (p < 0.01) and HNE (p < 0.05) in stroke patients compared with controls. Considering as covariates the level of consciousness (GCS < 9 vs > or = 9), possible sources of emboli (yes vs no), leukocyte count (< 10 x 10(9)/1 vs > or = 10 x 10(9)/1) and relevant comorbid diseases (yes vs no), exact multiple logistic regression analysis indicated that only the presence of possible cardiac sources of emboli was associated with changes in by-products of lipid peroxidation. If confirmed in a larger series of subjects, our results could have therapeutic implications, providing more support for the use of free radical scavengers in the acute care of stro...
In the myocardial cell, stimulation of the K opioid receptor is involved in the modulation of cyt... more In the myocardial cell, stimulation of the K opioid receptor is involved in the modulation of cytosolic calcium and pH homeostasis, as well as in the regulation of myofilament responsiveness to calcium. In the present study, we found that prodynorphin mRNA, which encodes for the synthesis of a common precursor of opioid peptides interacting with K sites, is synthesized both in atrial and ventricular tissue of the rat heart. In adult cultured rat ventricular cardiomyocytes, the level of prodynorphin mRNA did not differ from that detected in the original ventricular tissue. This finding indicates that the myocardial cell is a source for prodynorphin gene expression and has the potential for an intrinsic synthesis of dynorphin-related peptides.
Mitochondria extracted from the hearts of Wistar rats aged 6 and 24 months showed similar values ... more Mitochondria extracted from the hearts of Wistar rats aged 6 and 24 months showed similar values for the respiratory control index (RCI), state 3 oxygen consumption (QO2) and ADP/O measured using glutamate or succinate as substrates; with the exception that the QO2 of the aged rats was lower than that of the young rats in the presence of glutamate. The consumption of O2 induced by 2-oxoglutarate and ADP was similar in both age groups. Concentrations of external free Ca2+ ranging from 0.2 to 0.8 microM produced an increase in O2 consumption and ATP formation in the young mitochondria, with a maximum effect at 0.2 microM external free Ca2+. Little or no change in O2 consumption and ATP formation was evident in aged mitochondria following incubations in concentrations of external free Ca2+ ranging from 0.2 to 0.8 microM. The continuous rate of formation of ATP, measured in the presence of 0.2 microM external free Ca2+ using a luminescence method, confirmed the previous results. This st...
Research communications in chemical pathology and pharmacology, 1993
The GSH level in myocardial tissue represents an important defense mechanism against oxygen toxic... more The GSH level in myocardial tissue represents an important defense mechanism against oxygen toxicity. Since the ischemia-induced depletion of GSH might favour the cytotoxicity of oxygen-derived free radicals produced during reperfusion, we assessed the effects of the GSH donor, glutathione monoethylester, in anaesthetized pigs subjected to 90 minutes of coronary occlusion followed by 30 minutes reperfusion. The drug was infused intracoronarily at a dose of 1 mg/ml (0.5 ml/min) throughout the experimental period. After coronary occlusion and reperfusion, we found a decrease in GSH, ADP, ATP and phosphocreatine levels in reperfused compared with non-ischemic tissue. Less evident were the differences in mitochondrial function, there being only a reduction in the reperfused tissue of the respiratory control index and state 3 respiration values when pyruvate was used as substrate. The infusion with glutathione monoethylester decreased the depletion of tissue GSH and improved the GSH/GSSG...
The expression of the prodynorphin gene was investigated in adult cultured rat ventricular cardia... more The expression of the prodynorphin gene was investigated in adult cultured rat ventricular cardiac myocytes by using a sensitive solution hybridization RNase protection assay for the quantitative analysis of prodynorphin mRNA. Myocyte culture in high KCl resulted, after 4 h, in a marked increase in cellular prodynorphin mRNA, while a KCl treatment for 6, 12, or 24 h progressively down-regulated the levels of prodynorphin mRNA below the control value. Immunoreactive dynorphin B, a biologically active end product of the precursor, was found to be present in the culture medium in significantly higher amounts than in the cardiac myocytes. The levels of this biologically active K opioid receptor agonist significantly increased after 4 h of KCl treatment and were markedly reduced following a 24-h exposure of the cardiac myocytes to KCl. These KCl-induced effects were all abolished by cell incubation in the presence of the calcium channel blocker verapamil. In single cardiac myocytes, acut...
In mitochondria from alpha-tocopherol-deficient rabbit hearts (30 days), there was a close correl... more In mitochondria from alpha-tocopherol-deficient rabbit hearts (30 days), there was a close correlation between the decline in respiration and the incidence of membrane peroxidation. In the same mitochondria, an increased formation of oxygen radicals was also observed, whereas superoxide dismutase activity was only slightly depressed. The exposure of mitochondria to exogeneous oxygen radicals generated by a xanthine-xanthine oxidase system caused a marked decrease in their oxidative phosphorylation capacity associated with an increase in lipid peroxidation breakdown. This was particularly evident in mitochondria from alpha-tocopherol-deficient rabbits. In mitochondria from deficient animals that had been rehabilitated with alpha-tocopherol, the toxic effect of oxygen radicals was less evident.
International journal for vitamin and nutrition research. Internationale Zeitschrift für Vitamin- und Ernährungsforschung. Journal international de vitaminologie et de nutrition, 1982
The mitochondria extracted from hearts of alpha-tocopherol deficient rabbits showed a decreased m... more The mitochondria extracted from hearts of alpha-tocopherol deficient rabbits showed a decreased mitochondrial function and an increased formation of oxygen radicals associated with a decreased superoxide dismutase activity. The exposure of the alpha-tocopherol deficient mitochondria to exogeneous oxygen radicals caused a marked decrease in the mitochondrial function with respect to control mitochondria, which was partially reversed by the addition in vitro of alpha-tocopherol.
Ornithine decarboxylase activity evaluated during the perfusion of isolated rat hearts by a metho... more Ornithine decarboxylase activity evaluated during the perfusion of isolated rat hearts by a method 'in situ' was rapidly increased when the hearts were infused with isoprenaline (isoproterenol). Omission of Ca2+ from the perfusion medium or the administration of verapamil to the perfused hearts decreased the isoprenaline-stimulated ornithine decarboxylase activity, whereas a marked stimulatory effect was registered when the hearts were perfused with the Ca2+ ionophore A23187.
3H-tocopherol was administered by perfusion to rabbit hearts and rapidly entered the myocardial c... more 3H-tocopherol was administered by perfusion to rabbit hearts and rapidly entered the myocardial cells with an incorporation rate which was more evident inthe alpha-tocopherol deficient hearts than in the control hearts. During perfusion, the labelled alpha-tocopherol was slightly metabolized and 85% of the radioactivity was recovered as authentic alpha-tocopherol. The pattern of alpha-tocopherol distribution showed in both perfused hearts a significant binding of the radioactivity to the nuclei. The vitamin was also retained with high specific labelling in the mitochondria and in a lower degree in the microsomes and soluble fractions. Small amounts of radioactivity was found bound to the myofibrils. The study of the intranuclear distribution of tocopherol has revealed that the tocopherol-binding species were acidic nuclear macromolecules which exhibited characteristics of non-histone chromosomal proteins. Administration of alpha-tocopherol exhibited a positive effect on the stimulat...
Removal of dithiothreitol (DTT) from partially purified ornithine decarboxylase (ODC) led to an a... more Removal of dithiothreitol (DTT) from partially purified ornithine decarboxylase (ODC) led to an almost complete inhibition of enzymic activity. The inactivation was reversed by addition of millimolar concentrations of DTT, whereas natural reductants such as NADPH or NADH were ineffective, and GSH had only a limited effect. Addition of rat liver cytosol to the incubation mixture resulted in a noticeable re-activation of ODC; however, dialysed cytosol had little effect unless NADPH or GSH was present. Fractionation of rat liver cytosol by gel filtration on Sephadex G-75 yielded two fractions involved in the NADPH- and GSH-dependent re-activation of ODC: one designated 'A', eluted near the void volume (Mr greater than or equal to 60,000), and the other designated 'B', eluted later (Mr approx. 12,000). The NADPH-dependent mechanism required both fractions A and B for maximal ODC re-activation; the most effective concentration of NADPH was 0.15 mM, although a significant ...
Heart ornithine decarboxylase (ODC) from isoproterenol treated rats was compared to heart ODC fro... more Heart ornithine decarboxylase (ODC) from isoproterenol treated rats was compared to heart ODC from control rats. Isoproterenol administration did not significantly change Km for ornithine, but it induced a marked increase of Vmax, X Km for pyridoxal phosphate (PLP) was somewhat reduced. Both Kornm and Vmax were a function of the dithiothreitol (DTT) concentration, in a similar way for control and stimulated enzyme. Two ODC forms were detected by ion exchange chromatography in both control and isoproterenol treated hearts. In control heart, ODC specific activity was high in cytosol and nucleoli. Isoproterenol administration induced a remarkable increase of the cytosolic enzyme only.
Cyanide-resistant respiration in heart homogenates supplemented with 1 mM NADH was greater in hyp... more Cyanide-resistant respiration in heart homogenates supplemented with 1 mM NADH was greater in hypertrophied homogenates (60 days banding) with respect to control homogenates, particularly when the homogenates were incubated in 100% oxygen. The intermyofibrillar mitochondria from hypertrophied hearts produced more superoxide radicals than sub-sarcolemmal mitochondria, and both values were greater than in the unbanded group. H2O2 formation was more evident in the intact mitochondria prepared from hypertrophied hearts than in those of the control hearts. Moreover, the perfusion of isolated hearts in anoxic and reoxygenated conditions caused a greater lipoperoxidative and functional damage at the mitochondrial level in hypertrophied hearts than in the control hearts. These results, correlate with the reduction in mitochondrial function found in the overloaded hearts, suggest an involvement of the reactive species of oxygen in the formation of cardiac damage induced by prolonged aortic b...
Research communications in chemical pathology and pharmacology, 1989
Trimetazidine at concentrations above 100 microM competed with cytochrome c in scavenging O2.- ra... more Trimetazidine at concentrations above 100 microM competed with cytochrome c in scavenging O2.- radicals formed by the reaction catalyzed by the xanthine oxidase enzyme upon xanthine. This scavenger effect was also observed when O2.- were generated by active human neutrophils in which the rate of O2.- formation was monitored by following the reduction of cytochrome c or the emission of luminol-dependent chemiluminescence. An additional scavenger effect of trimetazidine was measured in a OH. chemical generating system whereby the breakdown of deoxyribose by the thiobarbituric acid assay was detected. This study suggests that trimetazidine might function as an antioxy radical compound in conditions of increased oxy radical production.
After ligation of the left coronary artery, porcine cardiac mitochondria were isolated by homogen... more After ligation of the left coronary artery, porcine cardiac mitochondria were isolated by homogenizing the tissue and treating the myofibrillar pellet with nagarse. When compared with unligated controls, the ischemic myocardium showed decreases in phosphocreatine (to 41%), ATP (to 56%) and in the mitochondrial respiratory control index (to 69% and 78% as measured with glutamate and succinate respectively). No changes were found in the corresponding P/O ratios. Similar results were obtained upon separation of the mitochondria into two main fractions by a density gradient technique, though only one of these fractions showed a fall in succinate-supported respiration. The results suggest that ischemia decreases the NADH-dehydrogenase activity of cardiac mitochondria.
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