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  • 1
    Electronic Resource
    Electronic Resource
    Regional oxygen supply and consumption balance in experimental left ventricular hypertrophy (1990)
    Springer
    Basic research in cardiology 85 (1990), S. 575-584 
    Details
    ISSN: 1435-1803
    Keywords: aortic valvestenosis ; coronaryblood flow ; myocardialO 2 consumption ; cardiachypertrophy ; dog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of the present study was to determine if the relationship between myocardial O2 supply and O2 consumption was preserved after prolonged pressure overload due to aortic valve stenosis. This was examined in anesthetized open-chest dogs in which the aortic valve was plicated 6 months previously. We measured coronary blood flow with radioactive microspheres and regional small vessel O2 saturation with microspectrophotometry, to obtain O2 supply, and O2 consumption. Regional O2 consumption was calculated as the product of flow and O2 extraction. The left ventricular weight/body weight ratio was 81% greater in the dogs with aortic valve stenosis. There were no hemodynamic differences between the groups except that left ventricular systolic pressure was 38±22 mm Hg greater than aortic in the hypertrophied group. Coronary blood flow did not differ between the control and hypertrophied groups nor were there subepicardial vs subendocardial differences. When maximal coronary flow was determined with chromonar (10 mg/kg), the flow increase was significantly attenuated in the hypertrophied subendocardium (242.1±82.3 (hypertrophy) vs 512.4±204.1 ml·min−1·100 g−1 (control)). There were no significant differences in O2 extraction or O2 consumption/g between control and hypertrophied animals. There was a significantly lower O2 supply/consumption ratio in the subendocardium compared to the subepicardium of both groups. However, the O2 supply/consumption ratio was not decreased by hypertrophy. Thus, despite significant hypertrophy, a loss of flow reserve and a high left ventricular pressure, O2 supply/consumption balance is preserved in valvular aortic stenosis at rest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01907892
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  • 2
    Electronic Resource
    Electronic Resource
    Intracellular collagen-like material in mouse embryonic mesenchymal cells incubated with TNF-α and IL-1β in organoid culture (1996)
    Springer
    Cell & tissue research 284 (1996), S. 509-515 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Intracellular collagen-like material ; Blastemal cells ; Cytokines ; Organoid cultures ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Blastemal cells of embryonic mouse limb buds (day 12) were cultivated in organoid cultures in the presence of the human recombinant cytokines interleukin-1β (IL-1β) and tumour necrosis factor α (TNF-α). The effects of both cytokines (applied alone or together) on mesenchymal cells were demonstrated by electron microscopy. Cultures treated with TNF-α (alone or in combination with IL-1β) showed several mesenchymal cells with numerous irregularly shaped membrane-bordered cavities containing thick bundled tannic-acid-positive fibrillar structures that resembled loosened collagen fibrils, whereas cells exposed to IL-1β alone did not exhibit such changes. These findings are discussed in the light of two hypotheses: the phagocytosis of extracellular collagen fibrils, and fibrillogenesis resulting from incongruity of synthesis and secretion rates of procollagen; our results favour the former.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050613
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The oxygen wasting effect of isoproterenol is altered by chemical denervation and cardiac hypertrophy (1996)
    Springer
    Basic research in cardiology 91 (1996), S. 308-318 
    Details
    ISSN: 1435-1803
    Keywords: β-adrenergic stimulation ; segment work ; regional blood flow ; regional O2 consumption ; efficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We tested the hypothesis that isoproterenol would increase myocardial work and O2 consumption at reduced efficiency and that both left ventricular hypertrophy and chemical sympathectomy would lead to changes in this myocardial efficiency response. Left ventricular hypertrophy was produced by aortic valve plication in 23 puppies. Six months later, sympathetic denervation (6-hydroxydopamine) was produced in 12 hypertrophied and 10 non-hypertrophied dogs, 5 days prior to acute experiments. Ten non-hypertrophied and 11 hypertrophied animals were not denervated. Measurements were made before and during an isoproterenol infusion (0.5 μg/kg/min). Regional myocardial work was calculated as the integrated product of force (miniature transducer) and segment shortening (ultrasonic crystals). Regional O2 consumption was calculated from regional blood flow (microspheres) and regional O2 saturations (microspectrophotometry). In all groups, regional O2 consumption increased with isoproterenol (non-hypertrophied, non-sympathectomized 6.5±0.8 to 20.3±5 ml O2/min/100 g, non-hypertrophied, sympathectomized 5.0±0.7 to 10.0±1.5, hypertrophied, nonsympathectomized 9.8±1.3 to 16.2±2.2, hypertrophied, sympathectomized 6.1±0.5 to 13.3±1.6). Regional segment work also increased in all groups with isoproterenol stimulation (non-hypertrophied, non-sympathectomized 781±73 to 1197±61 g·mm/min, non-hypertrophied, sympathectomized 996±221 to 2118±412, hypertrophied, non-sympathectomized 1031±145 to 3262±753, hypertrophied, sympathectomized 721±116 to 1745±402). In the non-hypertrophied, non-sympathectomized group, efficiency (work/O2 consumption) was significantly decreased from 122±17 to 76±9 g·mm/ml O2/100 g demonstrating an “oxygen wasting” effect. In the hypertrophied, non-sympathectomized group, segment efficiency significantly increased from 94±19 to 250±63. In both sympathectomized groups, efficiency was not altered by isoproterenol. Thus the oxygen wasting effect of β-adrenergic stimulation was reversed by left ventricular hypertrophy and blocked by sympathectomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00789303
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  • 4
    Electronic Resource
    Electronic Resource
    The negative functional and metabolic effects of muscarinic stimulation are enchanced byβ-adrenergic activation in control and hypertrophic dog hearts in vivo (1997)
    Springer
    Basic research in cardiology 92 (1997), S. 391-401 
    Details
    ISSN: 1435-1803
    Keywords: Cardiac hypertrophy ; acetylcholine ; dog ; β-adrenergic stimulation ; myocardial O2 consumption ; regional myocardial function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of the current study was to determine if the effects of muscarinic stimulation on left ventricular function and metabolism are greater during β-adrenergic activation, whether a cyclic GMP-mediated mechanism is responsible, and if this is altered by left ventricular hypertrophy (LVH) induced by aortic valve stenosis. Acetylcholine (Ach) (5 μg/kg/min) and/or isoproterenol (Iso) (0.1 μg/kg/min) was infused into a branch of the left anterior descending (LAD) artery in 8 control and 8 LVH open-chest anesthetized dogs. LVH increased heart weight, heart-to-body weight ratio and systolic left ventricular pressure. LVH reduced muscarinic receptor density (fmol/mg protein) (control: 149.2±18.6; LVH: 77.8±8.6), but not affinity. Alone, Ach had no effect on regional force, work or metabolism. Iso increased peak force (g) (control: baseline-7.4±0.4; Iso-12.4±2.2; LVH: baseline-6.7±0.8; Iso-16.3±2.7, regional work (g mm/min)) (control: baseline-1250±186; Iso-1813±409; LVH: baseline-927±235; Iso-1244±222), and O2 consumption (ml O2/min/100 g) (control: baseline-3.3±0.2; Iso-8.1±2.0; LVH: baseline-4.8±1.0; Iso-8.3±1.1). During Iso, Ach reduced segment shortening (control: Iso-14.5±1.2; Iso+Ach-10.5±1.8; LVH: Iso-10.4±1.5; Iso+Ach-7.6±1.3) and peak force (control: Iso+Ach-7.7±1.0; LVH: Iso+Ach-10.5±1.4). Ach also reduced work (control: Iso+Ach-875±217; LVH: Iso+Ach-776±180) and O2 consumption (control: Iso+Ach-3.4±0.7; LVH: Iso+Ach-3.6±0.6) in the presence of Iso. Cyclic GMP was higher in the LVH animals during all treatments and was elevated from baseline by Ach in both groups. Neither Iso nor Iso+Ach had a significant effect on cyclic GMP. Thus, the negative functional and metabolic effects of muscarinic stimulation are enhanced during β-adrenergic activation. This does not, however, appear to be dependent on a cyclic GMP-mediated mechanism. Despite reduced number of muscarinic receptors, this response was not altered by pressure-induced cardiac hypertrophy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00796213
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