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  • 1
    Electronic Resource
    Electronic Resource
    Contractile properties of skinned preparations from ischaemic canine myocardium and coronary arteries (1993)
    Springer
    Pflügers Archiv 425 (1993), S. 82-89 
    Details
    ISSN: 1432-2013
    Keywords: Myocardial ischaemia ; Myocardium ; Vascular smooth muscle ; Dog ; Contractile proteins ; Calcium dependence ; Myosin phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The influence of prolonged ischaemia on the regulation of contraction in the myocardium and in the smooth muscle of coronary arteries was investigated. Chemically skinned preparations were used which enabled the contraction to be studied with the environment of the contractile filaments controlled. Myocardial ischaemia was produced in anaesthetized adult beagle dogs by occlusion of the left anterior descending artery for 3 h and followed by 30 min reperfusion. Myocardial tissue and segments from coronary arteries were obtained from the ischaemic infarcted wall region (“in vivo ischaemic”) and compared with control preparations from perfused coronary arteries and from the free wall of the left ventricle. Coronary and myocardial preparations were also obtained from the heart after a 3 h period in vitro under anoxic conditions at 37°C (“in vitro ischaemic”) simulating a state of extreme ischaemia. Control myocardial fibres were fully relaxed at pCa (-log-[Ca2+]) 9 and developed 24±5% (n=7) of maximum force at intermediate calcium concentration (pCa 5.5). In contrast, the in vivo and in vitro ischaemic preparations produced force at pCa 9 (28±13 and 39±8%, respectively, n=5 and 7) and showed an increased force development at pCa 5.5 (53±11 and 75±5%). The in vivo and in vitro ischaemic coronary arteries relaxed more slowly following calcium removal than control vessels. The in vitro ischaemic vascular preparations developed active force at pCa 9 and showed increased levels of myosin light chain phosphorylation and reduced phosphatase activity. This suggests a reduced rate of dephosphorylation as a cause for the changes in contracile behaviour of the smooth muscle. In conclusion, extreme ischaemia in vitro is associated with a loss of calcium regulation and an increased calcium sensitivity of the contractile system in myocardium and changes in the phosphorylation/dephosphorylation reactions of coronary arteries. The changes in myocardium appear to occur also during ischaemia in vivo, and might contribute to contracture development in cells under conditions when adenosine triphosphate synthesis is reestablished after reperfusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374507
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Volume replacement in trauma patients within the first 24 h and its impact on the interpretation of biochemical data (2000)
    Springer
    Langenbeck's archives of surgery 385 (2000), S. 406-411 
    Details
    ISSN: 1435-2451
    Keywords: Clinical study Trauma Dilution Inflammatory response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Background and aims: Patients of the same and particularly of different trauma studies are primarily incomparable due to different volume replacements. The aim of this prospective study was to analyze the amount of initially administered fluids in trauma patients during the first 24 h and to estimate the impact of dilution on plasma protein concentrations (PPCs) of prostanoids. These substances are vascular endothelium-derived and are thus influenced by blood pressure. Patients/methods: Sixty-nine casualties suffering from multiple injuries were enrolled in the study. The amount of any fluid administered was scrutinized during the first 24 h. Patients were divided into subsets according to trauma severity by Injury Severity Score (ISS) (group=G-I: ≤9; G-II: 10–18; G-III: 19–32; G-IV: 〉32) and between survivors and non-survivors. At corresponding time points, hemoglobin, hematocrit (Hct) and PPC as well as prostaglandins (PGI, TxA, PGF2a) were evaluated at the site of accident, at hospital admission, and every hour thereafter for the first 24 h. Results: During this period, the total amount of infused fluids ranged between 0.5 l (G-I) and 〉48 l (G-IV). The higher the trauma severity, the greater the volume infused (G-III/IV P=0.0003 vs G-I/II). Simultaneously, PPC dropped markedly (P〈0.01). Patients who died within 36 h required higher volumes (P〈0.003) than survivors. PPC was linearly related (r 2=.6685, P〈0.001) to Hct. During the first 24 h, the time course of prostanoid concentration was altered when dilution is not taken into account. Conclusion: PPC proved a suitable parameter to estimate dilution effects and to adjust plasma concentrations of prostanoids. We recommend that consideration be given to possible dilution effects during the first 24 h when interpreting biochemical data in trauma patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004230000152
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    Paper (German National Licenses)
    Fulltext
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