Expression and Activity Patterns of Nitric Oxide Synthases and Antioxidant Enzymes Reveal a Substantial Heterogeneity Between Cardiac and Vascular Aging in the Rat

We investigated the effects of aging and ischemia-reperfusion (I/R) injury on the expression and activity of nitric oxide (•NO) synthases and superoxide dismutase (SOD) isoforms. To this end we perfused excised hearts from young (6months old) and old (31-34months old) rats according to the Langendorff technique. The isolated hearts were, after baseline perfusion for 30min, either subjected to 20min of global no-flow ischemia followed by 40min of reperfusion or were control-perfused (60min normoxic perfusion). Both MnSOD and Cu,ZnSOD expression remained unchanged with increasing age and remained unaltered by I/R. However, SOD activity decreased from 7.55 ± 0.1U/mg protein in young hearts to 5.94 ± 0.44 in old hearts (P<0.05). Furthermore, I/R led to a further decrease in enzyme activity (to 6.35 ± 0.41U/mg protein; P<0.05) in myocardium of young, but not in that of old animals. No changes in myocardial protein-bound 3-nitrotyrosine levels could be detected. Endothelial NOS (eNOS) expression and activity remained unchanged in aged left ventricles, irrespective of I/R injury. This was in steep contrast to peripheral (renal and femoral) arteries obtained from the same animals where a marked age-associated increase of eNOS protein expression could be demonstrated. Inducible NOS expression was undetectable either in the peripheral arteries or in the left ventricle, irrespective of age. In particular when associated with an acute pathology, which is furthermore limited to a certain time frame, changes in the aged myocardium with respect to enzymes crucially involved in maintaining the redox homeostasis, seem to be much less pronounced or even absent compared to the vascular aging process. This may point to heterogeneity in the molecular regulation of the cardiovascular aging proces

Expression and Activity Patterns of Nitric Oxide Synthases and Antioxidant Enzymes Reveal a Substantial Heterogeneity Between Cardiac and Vascular Aging in the Rat

We investigated the effects of aging and ischemia-reperfusion (I/R) injury on the expression and activity of nitric oxide (•NO) synthases and superoxide dismutase (SOD) isoforms. To this end we perfused excised hearts from young (6months old) and old (31-34months old) rats according to the Langendorff technique. The isolated hearts were, after baseline perfusion for 30min, either subjected to 20min of global no-flow ischemia followed by 40min of reperfusion or were control-perfused (60min normoxic perfusion). Both MnSOD and Cu,ZnSOD expression remained unchanged with increasing age and remained unaltered by I/R. However, SOD activity decreased from 7.55 ± 0.1U/mg protein in young hearts to 5.94 ± 0.44 in old hearts (P<0.05). Furthermore, I/R led to a further decrease in enzyme activity (to 6.35 ± 0.41U/mg protein; P<0.05) in myocardium of young, but not in that of old animals. No changes in myocardial protein-bound 3-nitrotyrosine levels could be detected. Endothelial NOS (eNOS) expression and activity remained unchanged in aged left ventricles, irrespective of I/R injury. This was in steep contrast to peripheral (renal and femoral) arteries obtained from the same animals where a marked age-associated increase of eNOS protein expression could be demonstrated. Inducible NOS expression was undetectable either in the peripheral arteries or in the left ventricle, irrespective of age. In particular when associated with an acute pathology, which is furthermore limited to a certain time frame, changes in the aged myocardium with respect to enzymes crucially involved in maintaining the redox homeostasis, seem to be much less pronounced or even absent compared to the vascular aging process. This may point to heterogeneity in the molecular regulation of the cardiovascular aging proces

β-2 Adrenergic Receptor Variants Affect Resting Blood Pressure and Agonist-Induced Vasodilation in Young Adult Caucasians

Abstract —Recent evidence suggests that the prodownregulatory Gly16 allele of the β-2 adrenergic receptor (β-2 AR) is associated with essential hypertension in African Caribbeans. To further investigate the effect of the glycine (Gly)16 and arginine (Arg)16 β-2 AR variants on hemodynamics, we investigated the agonist-mediated in vivo vasodilation in normotensive Austrian Caucasians and analyzed the results with respect to the Gly16/Arg16 polymorphism. Fifty-seven normotensive men, 20 to 32 years of age with body mass index of 18.7 to 29.9 kg/m 2 , were genotyped for the Arg16/Gly16 β-2 AR alleles. All 15 Gly16/Gly16 subjects, all 12 Arg16/Arg/16 subjects, and 27 of 30 heterozygous subjects underwent hemodynamic measurements while supine after an overnight fast. The observers were unaware of the subjects’ genotypes. The subjects received a graded infusion of the selective β-2 AR agonist salbutamol (0.07, 0.14, and 0.21 μg/kg per minute, respectively), each dose over 8 minutes. Stroke volume and blood pressure were determined continuously by means of impedance cardiography and oscillometry, respectively. The last 4 minutes of each infusion were evaluated statistically. Basal mean blood pressure was higher in the Gly16/Gly16 subjects compared with Arg16/Arg16 subjects (mean±SD: 81.6±6.14 versus 75.2±4.93 mm Hg, P &lt;0.01). Homozygous Gly16 subjects showed a significantly decreased vasodilation during the first dose of salbutamol infusion compared with Arg16/Arg16 subjects (Δtotal peripheral resistance index −17.9±14.4 versus −30.6±8.3%, P &lt;0.01) despite increased sympathetic counterregulation in the Arg16/Arg16 group (Δheart rate +16.9±7.0% versus +8.6±7.0%, P &lt;0.01; Δcardiac index +39.5±18.5% versus 21.4±18.8%, P &lt;0.05). Our results provide additional evidence that the Gly16/Arg16 alleles of the β-2 AR are intimately related to blood pressure regulation and deserve further studies in the pathogenesis of essential hypertension. </jats:p

Expression and Activity Patterns of Nitric Oxide Synthases and Antioxidant Enzymes Reveal a Substantial Heterogeneity Between Cardiac and Vascular Aging in the Rat

We investigated the effects of aging and ischemia-reperfusion (I/R) injury on the expression and activity of nitric oxide (•NO) synthases and superoxide dismutase (SOD) isoforms. To this end we perfused excised hearts from young (6months old) and old (31-34months old) rats according to the Langendorff technique. The isolated hearts were, after baseline perfusion for 30min, either subjected to 20min of global no-flow ischemia followed by 40min of reperfusion or were control-perfused (60min normoxic perfusion). Both MnSOD and Cu,ZnSOD expression remained unchanged with increasing age and remained unaltered by I/R. However, SOD activity decreased from 7.55 ± 0.1U/mg protein in young hearts to 5.94 ± 0.44 in old hearts (P<0.05). Furthermore, I/R led to a further decrease in enzyme activity (to 6.35 ± 0.41U/mg protein; P<0.05) in myocardium of young, but not in that of old animals. No changes in myocardial protein-bound 3-nitrotyrosine levels could be detected. Endothelial NOS (eNOS) expression and activity remained unchanged in aged left ventricles, irrespective of I/R injury. This was in steep contrast to peripheral (renal and femoral) arteries obtained from the same animals where a marked age-associated increase of eNOS protein expression could be demonstrated. Inducible NOS expression was undetectable either in the peripheral arteries or in the left ventricle, irrespective of age. In particular when associated with an acute pathology, which is furthermore limited to a certain time frame, changes in the aged myocardium with respect to enzymes crucially involved in maintaining the redox homeostasis, seem to be much less pronounced or even absent compared to the vascular aging process. This may point to heterogeneity in the molecular regulation of the cardiovascular aging proces